Toolkit · Tax

The Business Tax Toolkit

26 U.S.C. § 11

Type
Toolkit
Jurisdiction
National
Date
2026-05-26
Topic
Tax

This toolkit is the front door to business tax on UpLaw. It maps the whole terrain in ten pillars — entity classification and the check-the-box rules, the corporate income tax, pass-through taxation under Subchapters S and K, the taxation of compensation and equity (options, restricted stock, 83(b), profits interests, and 409A), the founder-focused breaks of Section 1202 and Section 199A, payroll and employment taxes and worker classification, state and local tax and nexus after Wayfair, transaction tax in mergers and acquisitions, tax-exempt organizations, and tax controversy, penalties, and collections. Each pillar gives you the plain-English doctrine, the anchor authority in the Internal Revenue Code, the traps that catch real businesses, and a link into UpLaw's deeper guides, checklists, and toolkits. A running worked example follows one fictional company, Sablewood Robotics, from formation through payroll, equity grants, and an exit. Use it as a research map: skim the landscape, jump to the pillar you need, and follow the links down into the detail.

The Business Tax Toolkit

Tax > Business Tax | Published 26 May 2026 - Updated 23 June 2026 | UpLaw - uplaw.us

Every business decision is also a tax decision. What you call the entity, how you pay the people, where you ship the goods, and how you sell the company are all legal questions with a tax answer attached — and the tax answer is usually the one that decides how much of the deal you keep.

Keywords: business tax, entity classification, check-the-box, C corporation, S corporation, partnership taxation, 83(b) election, 409A, QSBS, Section 199A, payroll taxes, worker classification, economic nexus, Wayfair, asset vs. stock sale, tax-exempt status, IRS audit

How to read this toolkit

Business tax is not one subject. It is a stack of ten separate regimes that happen to share a statute book, and a business touches almost all of them before it is five years old. The founder who wonders whether to be an LLC or a corporation is in Pillar 1. The same founder, eighteen months later, wondering whether the 1099 designer is really a contractor, is in Pillar 6. At exit, wondering why the buyer wants an asset purchase and why that costs the seller money, she is in Pillar 8. Different rules, different sections of the Code, different advisors — but one continuous business.

This toolkit walks that stack pillar by pillar. It is a research map, not a treatise. Each pillar gives you the doctrine in plain English, the anchor authority in the Internal Revenue Code and the regulations, the classic traps, and a link into UpLaw's deeper treatment where the real detail lives. The deep dive underneath everything below is Business Taxation: A Comprehensive Guide to Entity Choice and Federal Income Tax; keep it open in the next tab.

Use the toolkit three ways. Read it end to end once, to build the mental model of how tax attaches to a business at every stage. Jump to a pillar when you have a live question and follow the links. Or use the consolidated checklist near the end as a gated audit of any company you advise or run.

One boundary line to fix before you start. Federal income tax is federal — the Internal Revenue Code (Title 26 of the U.S. Code), the Treasury regulations, and the federal courts. Everything this toolkit says about tax is a national rule unless flagged otherwise. But the entity whose income the Code taxes is a creature of state law: a Delaware corporation, a Colorado LLC, a New York partnership. Federal tax law does not create entities; it classifies them.

That matters twice over. First, corporate law — formation, charter, stock, board duties, dissolution — is state law, and there is no national corporation statute. Where this toolkit describes corporate mechanics, the reference point is Delaware (the Delaware General Corporation Law), because that is where most venture-backed companies incorporate and because Delaware's case law is the most developed; it is a reference point, not a rule that binds a California or Texas entity. Confirm your own state's corporation or LLC act before relying on any structural step. Second, state and local tax (Pillar 7) is its own fifty-state patchwork with only constitutional limits at the outer edge — there is no such thing as "the" state rule on nexus, apportionment, or sales tax. Whenever this toolkit says "the rule," it means the federal tax rule unless it says otherwise.

Meet Sablewood Robotics. Our running example is a fictional company founded by two engineers, Dara and Miguel, who left a warehouse-automation firm to build inventory robots. Over the pages below Sablewood will incorporate, elect its tax classification, grant founder stock and employee options, hire W-2 employees and misclassify one contractor, sell into thirty states, get audited, and finally get acquired. Every mistake it makes is one a real company makes every week.

The business-tax landscape at a glance

  1. Entity classification and choice — What the Code thinks your business is, and how you change its mind. (Treas. Reg. § 301.7701-3)
  2. Taxing the C corporation — The 21% entity rate, the second layer at the shareholder level, and the planning that follows. (26 U.S.C. § 11; §§ 301, 316, 351)
  3. Taxing pass-throughs — S corporations under Subchapter S and partnerships/LLCs under Subchapter K. (26 U.S.C. §§ 1361–1379; §§ 701–777)
  4. Compensation and equity — Wages, options, restricted stock, the 83(b) election, profits interests, and the 409A trap. (26 U.S.C. §§ 83, 409A, 422)
  5. Founder breaks — Qualified small business stock and the pass-through deduction. (26 U.S.C. §§ 1202, 199A)
  6. Payroll and employment taxes; worker classification — FICA, FUTA, withholding, and who is an employee. (26 U.S.C. §§ 3101–3128, 3301–3311, 3402, 6672)
  7. State and local tax and nexus — Income, franchise, and sales tax after Wayfair. (South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018); P.L. 86-272)
  8. Transaction tax — Asset sales, stock sales, and tax-free reorganizations. (26 U.S.C. §§ 338, 368, 1060)
  9. Tax-exempt organizations — Charities, the operational test, and unrelated business income. (26 U.S.C. §§ 501(c)(3), 511–514)
  10. Controversy, penalties, and collections — Audits, Appeals, Tax Court, liens, and levies. (26 U.S.C. §§ 6212, 6213, 6321, 6331, 6662, 7122)

Pillar 1 — Entity classification and choice

The first thing to understand about business tax is that the entity you form and the entity you are taxed as are two different choices. State law gives you a corporation, an LLC, a limited partnership. Federal tax law then sorts that state-law creature into one of four buckets: taxed as a C corporation, an S corporation, a partnership, or disregarded (as a sole proprietorship or a branch of its owner).

The sorting mechanism is the "check-the-box" regime of Treas. Reg. § 301.7701-3. An eligible entity with two or more members defaults to partnership treatment; a single-member eligible entity defaults to disregarded. Either can affirmatively elect corporate treatment by filing Form 8832. An entity incorporated under a state corporation statute is a per se corporation under Treas. Reg. § 301.7701-2(b) and cannot elect out — a Delaware Inc. is a corporation for tax, period. It can, however, layer an S election on top under 26 U.S.C. § 1362 (Form 2553) if it meets the eligibility rules. An LLC can do the same: check the box to be a corporation, then elect S status.

So "LLC vs. corporation" is really two questions stacked: which state-law wrapper, and which federal tax box. The practical grid:

State-law entity Default federal tax treatment Common elections
Corporation (Inc.) C corporation S election under § 1362
Multi-member LLC Partnership Corporation (Form 8832), then optionally S
Single-member LLC Disregarded entity Corporation (Form 8832), then optionally S
Limited partnership Partnership Rarely elects out
Sole proprietorship Disregarded (Schedule C) Incorporate to change

Why founders pick what they pick. Venture-backed startups overwhelmingly form as Delaware C corporations — not because the C corporation is tax-efficient (it is not, in the abstract), but because institutional investors, preferred stock, option pools, and § 1202 qualified small business stock all require it. Funds with tax-exempt limited partners cannot accept the unrelated business taxable income that flows out of a partnership. Consulting firms, real-estate ventures, and closely held operating businesses more often choose LLC/partnership treatment, which delivers a single layer of tax and enormous allocation flexibility. Service businesses with meaningful owner-employees often land on the S corporation for its self-employment-tax arbitrage (Pillar 3).

Sablewood forms Sablewood Robotics, Inc. in Delaware, qualifies to do business in Colorado where it operates, and takes the default C corporation treatment. The founders considered an LLC — the losses in year one would have flowed to their personal returns — but they intend to raise a priced round and to hold their shares for § 1202 treatment, and both point to the C corporation.

Traps. Do not elect S status without checking eligibility first; the one-class-of-stock rule alone kills most companies that ever plan to issue preferred. Do not "convert" casually — a partnership-to-corporation conversion is usually tax-free under § 351, but a corporation-to-partnership conversion is a liquidation and is generally taxable at both levels. And do not let the state-law and tax-law layers drift apart in your documents: an operating agreement that speaks in "distributions" and "capital accounts" is describing a partnership, and it will make no sense if the LLC has elected corporate treatment.

Work the decision with Choosing a Tax Entity: A Practical Checklist, and pair it with the non-tax formation mechanics in Incorporating a Startup the Right Way: A Founder's Legal Checklist. If you are stacking entities — a holding company over operating subsidiaries — read Running Multiple Businesses Under One Structure: A Deep Dive into Holding, Operating, and Parent Companies, because consolidated returns, qualified subchapter S subsidiaries, and disregarded single-member LLCs each behave very differently inside a group.

Pillar 2 — Taxing the C corporation

The C corporation pays its own income tax. Since the 2017 Tax Cuts and Jobs Act, the rate is a flat 21% under 26 U.S.C. § 11(b). That is the first layer. The second layer arrives when the corporation distributes: a distribution out of earnings and profits is a dividend under §§ 301 and 316, taxable to the shareholder, and — critically — not deductible by the corporation. That is the "double tax," and every C corporation planning technique in existence is an attempt to manage it.

The classic management technique is to zero out earnings with deductible payments: salaries, bonuses, rent to a shareholder-landlord, interest on shareholder debt. Each has a limit. Compensation is deductible only to the extent it is reasonable (§ 162(a)(1)), and the IRS routinely recharacterizes excessive owner compensation in a profitable closely held C corporation as a disguised dividend. Shareholder debt can be recharacterized as equity under § 385 principles, converting deductible interest into a nondeductible dividend. And the accumulated earnings tax (§ 531) and personal holding company tax (§ 541) exist precisely to punish corporations that hoard earnings to avoid the shareholder-level tax.

Getting in is usually free. Under 26 U.S.C. § 351, a transfer of property to a corporation solely in exchange for stock is tax-free if the transferors are in control immediately after — 80% of voting power and 80% of each class of nonvoting stock (§ 368(c)). This is what makes founders' contributions of cash and IP at formation a nonevent. Two cautions: services are not property, so stock issued for services is compensation under § 83 (Pillar 4), not a § 351 exchange; and boot (cash or other property) triggers gain recognition up to the boot received.

Getting out is rarely free. A liquidating C corporation recognizes gain on the distribution of appreciated assets under § 336, and the shareholders recognize gain on the exchange of their stock under § 331. Two layers, on the way out, on the same appreciation. This asymmetry — free in, expensive out — is why the C corporation election is so hard to unwind and why the choice in Pillar 1 deserves real thought.

Sablewood loses money for three years, so its 21% liability is zero and it accumulates net operating losses. Those NOLs are an asset — one that a future acquirer will diligence, because § 382 sharply limits their use after an ownership change, and post-TCJA NOLs can offset only 80% of taxable income under § 172.

For the full doctrinal treatment, see Business Taxation: A Comprehensive Guide to Entity Choice and Federal Income Tax. The classic treatise here is Bittker & Eustice, Federal Income Taxation of Corporations and Shareholders, which remains the reference work for §§ 301–368. Because the corporation's own governance obligations run in parallel with its tax obligations, keep Corporate Governance and Fiduciary Duties: A Comprehensive Guide for Directors and Officers and Board Governance, Minutes, and Corporate Formalities: A Practical Checklist close at hand — the board resolutions that approve a dividend, a redemption, or an option grant are also the documentary record the IRS will ask for.

Pillar 3 — Taxing pass-throughs: S corps and partnerships/LLCs

A pass-through entity pays no entity-level income tax. Income, deductions, and credits flow to the owners, who report them on their own returns whether or not cash was distributed. That last clause causes more owner distress than any other sentence in tax law: you can owe tax on income you never received. Well-drafted governing documents therefore include a tax distribution covenant.

The S corporation (26 U.S.C. §§ 1361–1379)

An S corporation is a corporation that elects to be taxed roughly like a partnership. The eligibility rules of § 1361 are strict and unforgiving:

  • No more than 100 shareholders (family members can be counted as one).
  • Only individuals, estates, and certain trusts may hold shares — no corporations, no partnerships, no non-resident aliens.
  • One class of stock. Differences in voting rights are fine; differences in distribution or liquidation rights are not.
  • It must be a domestic corporation and not an ineligible corporation.

Blow any one of these and the S election terminates — sometimes retroactively, sometimes inadvertently, occasionally catastrophically at the worst possible moment (which is during buy-side diligence). Inadvertent-termination relief exists under § 1362(f), and late-election relief under Rev. Proc. 2013-30, but both cost time and money.

The reason people accept those constraints is the self-employment tax arbitrage. An S corporation's distributive share of income is not subject to self-employment tax. Wages paid to an owner-employee are subject to FICA. So an owner has an incentive to take a small salary and a large distribution — and the IRS has an equally strong incentive to challenge it. The requirement is reasonable compensation: an owner who performs substantial services must be paid a reasonable wage before distributions. Rev. Rul. 74-44 established the recharacterization principle, and the courts have consistently backed the Service — Watson v. United States, 668 F.3d 1008 (8th Cir. 2012), upholding the recharacterization of an accountant-owner's S corporation distributions as wages, is the case everyone cites. Note that there is no safe-harbor percentage in the statute or the regulations; "reasonable" is a facts-and-circumstances judgment measured against what the market would pay someone else to do the owner's job. A $24,000 salary on $200,000 of profit is not a strategy; it is an audit.

Built-in gains. A C corporation that converts to S status carries a § 1374 built-in gains tax on appreciation that existed at conversion, if the asset is sold within the recognition period. This alone defeats the common fantasy of converting to S right before a sale.

Partnerships and LLCs (Subchapter K, §§ 701–777)

Subchapter K is the most flexible — and most complex — regime in the Code. Contributions of property are tax-free under § 721 (with none of § 351's control requirement). Distributions are generally tax-free under § 731 to the extent of basis. Partners take basis in their interests that includes their share of partnership liabilities under § 752 — a feature with no analogue in Subchapter S, and the reason real estate lives in partnerships: debt-financed basis supports debt-financed losses.

The flexibility lives in § 704. Partners may allocate items in almost any way they choose, so long as the allocation has substantial economic effect under the § 704(b) regulations (or is in accordance with the partners' interests in the partnership). Layered on top is § 704(c), which forces built-in gain or loss on contributed property back to the contributing partner. Special allocations, preferred returns, waterfalls, and carried interests are all § 704 constructs.

Self-employment tax is the partnership's rough edge. A general partner's distributive share of trade-or-business income is self-employment income under § 1402(a); the "limited partner" exclusion of § 1402(a)(13) is genuinely unsettled as applied to LLC members and to limited partners who work in the business, and the IRS has been litigating it aggressively. Do not assume an LLC membership interest is SE-tax-free because it is called "limited."

Finally, note the BBA centralized partnership audit regime (from the Bipartisan Budget Act of 2015): the IRS now audits and collects from the partnership itself through an imputed underpayment, unless the partnership elects out or makes a push-out election under § 6226. Every LLC and partnership agreement needs a designated partnership representative with defined powers. If yours does not, amend it.

Pillar 4 — Compensation and equity: options, restricted stock, 83(b), profits interests, 409A

Anything of value transferred to a service provider is compensation until proven otherwise. 26 U.S.C. § 83 is the governing rule: property transferred in connection with the performance of services is taxable as ordinary income when it becomes substantially vested — that is, when it is transferable or no longer subject to a substantial risk of forfeiture — measured by its fair market value at that later date, less any amount paid.

That timing rule is the whole game. Founder stock subject to a four-year vesting schedule is not substantially vested at grant. Absent an election, the founder recognizes ordinary income at each vesting date, on the then-fair-market value, of stock she cannot sell. If the company succeeds, that is a career-defining tax disaster.

The 83(b) election is the escape hatch. Under § 83(b), the service provider may elect, within 30 days of the transfer, to include the value at grant instead. At formation, when the stock is worth essentially nothing, that means including nearly zero income, starting the capital-gains holding period immediately, and starting the § 1202 clock. The 30-day deadline is jurisdictional in practice: there is no reasonable-cause relief, no extension, no fix. Every founder, every early advisor, every recipient of restricted stock must file it. Do it with Founder Equity, Vesting, and the 83(b) Election: A Practical Checklist.

Dara and Miguel each receive 4,000,000 shares of Sablewood common at $0.0001 per share, subject to four-year vesting. Both file 83(b) elections on day 12. Total income reported: $400 each. Four years later, at the exit, that decision is worth several million dollars in tax.

Options. Two species:

  • Incentive stock options (ISOs, § 422) — employees only, $100,000 per-year vesting limit, exercise price at or above fair market value, holding periods of two years from grant and one from exercise. If the holding periods are met, the entire spread is long-term capital gain. But the spread at exercise is an alternative minimum tax preference item, which has bankrupted employees who exercised into a paper gain that later evaporated.
  • Nonqualified stock options (NSOs, § 83) — anyone, no limits, and the spread at exercise is ordinary compensation income subject to withholding, with a corresponding corporate deduction.

Profits interests. The partnership world's answer to the option. A profits interest gives the holder a share of future appreciation only, with a liquidation value of zero on the grant date. Under Rev. Proc. 93-27 and Rev. Proc. 2001-43, a properly structured profits interest is not a taxable event at grant. It is the most elegant equity-comp instrument in American tax law — and it is available only to LLCs and partnerships, not corporations. Note that a service partner who receives a profits interest becomes a partner, not an employee: no W-2, self-employment tax, quarterly estimates.

Section 409A sits over all of it. § 409A governs nonqualified deferred compensation and imposes, on failure, immediate income inclusion plus a 20% additional tax plus interest — on the employee. Options escape 409A only if the exercise price is at least fair market value on the grant date; a below-FMV option is deferred compensation. That is why private companies obtain an independent 409A valuation, which creates a presumption of reasonableness under the regulatory safe harbors (Treas. Reg. § 1.409A-1(b)(5)(iv)). Cheap options are not a gift to employees; they are a tax bomb with the employee's name on it.

Set the whole equity program in context with The Founder's Path from Formation Through Financing: A Roadmap and Resource Toolkit and, on the securities side of the same grants, Raising Capital: A Startup Securities Toolkit. If the company is funding itself on convertible instruments first, Simple Agreements for Future Equity: An Overview of How SAFEs Actually Work and Running a SAFE Financing Round: A Practical Checklist explain the instrument whose conversion later sets the capitalization the options price against.

Pillar 5 — Founder breaks: QSBS (Section 1202) and Section 199A

Two provisions do more for owner after-tax outcomes than all the rest of business tax planning combined.

Qualified small business stock — 26 U.S.C. § 1202

If you hold qualified small business stock, you may exclude gain on its sale — potentially all of it — from federal income tax. The requirements are technical and every one of them matters:

  • The issuer must be a domestic C corporation (never an S corp, never an LLC taxed as a partnership).
  • The stock must be acquired at original issuance, from the corporation, for money, property, or services — not bought from another shareholder.
  • The corporation's aggregate gross assets must not exceed the statutory ceiling immediately after issuance.
  • The corporation must satisfy the active business requirement: at least 80% of assets used in a qualified trade or business. Excluded businesses include health, law, engineering, accounting, actuarial science, performing arts, consulting, athletics, financial services, brokerage, banking, farming, extraction, and hospitality.
  • The stock must be held for the required period.

Two important vintage points. Legacy § 1202, governing stock issued under the pre-2025 rules, required a five-year hold for the full exclusion, applied a $50 million aggregate-gross-assets ceiling, and capped the exclusion at the greater of $10 million or 10x basis per issuer. Amended § 1202, applicable to stock issued on or after the effective date of the 2025 tax legislation, adds a tiered exclusion (a partial exclusion once a three-year hold is met, a larger one at four years, the full exclusion at five), raises the gross-asset ceiling, and raises the per-issuer dollar cap. Which version applies turns entirely on the issuance date of the particular block of stock — a company can easily hold both vintages in its cap table at once. Do not model an exit, and do not tell a founder what her exclusion is, without pulling the stock certificates and the exact current statutory figures. The dollar thresholds here are the single most-cited and most-often-stale numbers in startup tax; verify them at the moment of use.

The traps are structural and mostly unfixable after the fact. Converting an LLC to a C corporation starts the clock — and only the appreciation after conversion qualifies. Redemptions by the corporation near the issuance date can disqualify stock under the anti-abuse rules of § 1202(c)(3). Secondary purchases of founder stock never qualify (though § 1045 permits a rollover of QSBS proceeds into new QSBS within 60 days, which can preserve the benefit for a holder short of the holding period). And a company that drifts into consulting or financial services can fail the active-business test years after issuance.

Sablewood's stock is QSBS from day one. Dara's 83(b) election and her original-issuance purchase are what make the exclusion available at exit — two paragraphs of paperwork filed in the company's first month.

The pass-through deduction — 26 U.S.C. § 199A

§ 199A gives owners of pass-throughs a deduction of up to 20% of qualified business income, narrowing the gap between the 21% corporate rate and individual rates. Above income thresholds, the deduction is limited by a W-2 wages / qualified property test, and it is phased out entirely for specified service trades or businesses (SSTBs) — the same catalogue of professional services that § 1202 excludes. Originally scheduled to sunset after 2025, it was made permanent by the 2025 tax legislation; the thresholds are inflation-adjusted, so verify the current numbers.

The planning consequence: for a profitable non-SSTB pass-through, § 199A can make partnership or S treatment competitive with — often better than — a C corporation, because the C corporation's second layer of tax never goes away. For an SSTB above the thresholds, it does nothing, and the entity analysis changes accordingly. Run both models in Choosing a Tax Entity: A Practical Checklist.

Pillar 6 — Payroll and employment taxes; worker classification

Payroll tax is the most reliably fatal area of business tax, because unlike income tax, it is not the company's money.

The obligations. For every employee, the employer must (1) withhold federal income tax under § 3402, (2) withhold the employee's share of FICA — 6.2% Social Security up to the wage base and 1.45% Medicare with no cap (§§ 3101–3128), plus the 0.9% Additional Medicare Tax on high earners — (3) pay a matching employer FICA share, (4) pay FUTA unemployment tax under §§ 3301–3311, (5) deposit all of it on the applicable schedule, and (6) report on Forms 941 and 940 and issue W-2s. State withholding, state unemployment insurance, and workers' compensation ride alongside.

The trust fund. Amounts withheld from employees are held in trust for the United States. If they are not paid over, 26 U.S.C. § 6672 imposes the Trust Fund Recovery Penalty: 100% of the unpaid trust-fund amount, assessed personally against any responsible person who willfully failed to collect or pay it over. "Responsible person" is functional, not titular — a CFO, a controller, a bookkeeper with check-signing authority, or an outside board member with financial control can all qualify. "Willful" means knowing the taxes were unpaid and paying other creditors anyway. Corporate limited liability does not touch it, and it is generally not dischargeable in bankruptcy. When a struggling company decides to make payroll net and "catch up on the deposits next month," this is the statute that ends careers.

Worker classification. All of the above turns on whether the worker is an employee or an independent contractor. The federal test is the common-law control test (§ 3121(d)(2); Treas. Reg. § 31.3121(d)-1), asking who has the right to control the manner and means of the work — the same agency framework the Supreme Court applied in Nationwide Mutual Insurance Co. v. Darden, 503 U.S. 318 (1992). The old twenty-factor formulation survives in Rev. Rul. 87-41; the IRS today organizes the inquiry into behavioral control, financial control, and the relationship of the parties. A worker or firm may request a determination on Form SS-8. Section 530 of the Revenue Act of 1978 provides safe-harbor relief from reclassification liability for firms with a reasonable basis, consistent treatment, and consistent Forms 1099 — it is a lifeline, and it is lost the moment treatment is inconsistent.

Two warnings. First, the federal tax test is not the same as the FLSA economic-reality test, the NLRA test, or California's ABC test — a worker can be a contractor for one and an employee for another. Second, misclassification liability compounds: back withholding, both FICA shares, FUTA, penalties, state unemployment, and wage-and-hour exposure. Work through it with Classifying Workers: Employee or Independent Contractor — A Practical Checklist and the full doctrinal treatment in Worker Classification: A Comprehensive Guide to Employee and Independent Contractor Status. The overtime and minimum-wage consequences are in Wage and Hour Law Under the FLSA: A Comprehensive Guide, and the whole employment lifecycle is mapped in The Employment Law Toolkit: From Hiring to Separation.

Sablewood's mistake lands here. Its "contract" firmware engineer works full time, on Sablewood laptops, from Sablewood's shop, under Sablewood's schedule, and has done so for two years. He is an employee, and everyone on the engineering team knows it. When the state unemployment agency picks it up after he files a claim, the resulting audit runs both ways — state and federal — and the bill dwarfs whatever payroll tax Sablewood "saved."

Pillar 7 — State and local tax and nexus after Wayfair

State tax is not a footnote to federal tax; it is a separate system, fifty times over, with its own bases, its own rates, and its own filing obligations. The constitutional floor comes from the Commerce Clause and Due Process Clause, and the operative framework is Complete Auto Transit, Inc. v. Brady, 430 U.S. 274 (1977): a state tax on interstate commerce is valid if it (1) applies to an activity with substantial nexus, (2) is fairly apportioned, (3) does not discriminate against interstate commerce, and (4) is fairly related to services the state provides.

Sales tax after Wayfair. For fifty years, a state could not require an out-of-state seller to collect sales tax unless the seller had physical presence — the rule of Quill Corp. v. North Dakota, 504 U.S. 298 (1992). In South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018), the Supreme Court overruled Quill and held that economic nexus suffices. Substantially every state now imposes an economic-nexus threshold — South Dakota's, which the Court blessed, was $100,000 in sales or 200 separate transactions in the state — and many have also enacted marketplace facilitator laws pushing collection onto the platform. The practical consequence for any company selling online: you may have a collection obligation in dozens of states you have never visited, and the obligation is to collect from the customer. If you fail to collect, you generally owe it yourself, with interest and penalties, and the sales-tax statute of limitations often never starts running because no return was filed.

Income tax and P.L. 86-272. For net income taxes, a narrow federal shield survives: Public Law 86-272 (15 U.S.C. §§ 381–384) bars a state from imposing a net income tax on an out-of-state seller whose only in-state activity is the solicitation of orders for tangible personal property, approved and filled from outside the state. Note what it does not cover: services, intangibles, software delivered as a service, and any activity beyond solicitation. The Multistate Tax Commission's revised interpretation treats a range of internet activities — chat support, post-sale assistance, cookies that gather customer data — as exceeding solicitation, and several states have adopted it. A SaaS company gets essentially no protection from P.L. 86-272.

The other layers. Franchise and gross-receipts taxes (Delaware's franchise tax, California's $800 minimum, Texas's margin tax, Ohio's CAT, Washington's B&O) are not income taxes and are not shielded. Apportionment formulas increasingly use a single sales factor with market-based sourcing — meaning your tax follows your customers, not your offices. Payroll withholding follows the employee's work location, which is why a single remote hire can create nexus, registration, and withholding obligations in a new state. And most states now offer a pass-through entity tax (PTET) election, an elective entity-level tax designed to work around the federal individual cap on state and local tax deductions under § 164(b)(6) — a cap that the 2025 legislation raised temporarily, with phase-downs at higher incomes. Confirm current numbers before relying on either.

Sablewood, having sold robots into thirty states and hired two remote engineers in Texas and Georgia, discovers at diligence that it has unfiled sales-tax returns in eleven states. The fix is a voluntary disclosure agreement in each — a well-worn path that typically limits the lookback and abates penalties, but only if you get there before the state does.

Pillar 8 — Transaction tax: asset vs. stock sales and tax-free reorganizations

At exit, buyer and seller want opposite things, and the entire negotiation over structure is a fight about tax.

Asset sale. The buyer purchases the assets and assumes chosen liabilities. The buyer's dream: it takes a stepped-up basis in the assets, allocated under the residual method of 26 U.S.C. § 1060 across seven asset classes, and amortizes the goodwill over 15 years under § 197. It also leaves behind unknown liabilities. The seller's problem: for a C corporation, an asset sale is taxed at the corporate level and again when the proceeds are distributed. Two layers. This is the single biggest reason C-corp sellers resist asset deals — and the reason a founder holding QSBS wants a stock sale, because § 1202 excludes gain on the sale of stock, not assets.

Stock sale. The buyer purchases the shares. The seller gets one layer of tax, capital gain treatment, and the QSBS exclusion if available. The buyer gets no basis step-up (carryover basis inside the target) and inherits every liability, known and unknown — which is why buy-side diligence and the indemnity package get so much harder. Two bridges exist: a § 338(h)(10) election (available for S corporation targets and certain consolidated subsidiaries) and a § 336(e) election treat a stock purchase as a deemed asset sale for tax purposes, giving the buyer a step-up while the deal remains a stock sale in form. For S corporations, the F reorganization structure — reorganizing the target under § 368(a)(1)(F) into a holding company with a QSub beneath it, then selling LLC interests — has become the standard way to deliver a step-up without disturbing the S election.

Tax-free reorganizations. If the sellers take buyer stock rather than cash, the deal can qualify as a reorganization under § 368 — an "A" statutory merger, a "B" stock-for-stock exchange, a "C" stock-for-assets exchange — and the sellers defer gain under § 354, recognizing only to the extent of boot (§ 356). Judicial doctrines police it: continuity of interest (the sellers must retain a meaningful equity stake), continuity of business enterprise, and business purpose — the last from Gregory v. Helvering, 293 U.S. 465 (1935), the founding case of American anti-abuse doctrine. Deferral is not forgiveness: the sellers take a substituted basis, and the tax comes when they sell the buyer's stock.

Three items that ambush deals. § 280G golden-parachute rules can impose a 20% excise tax on executives and deny the company a deduction on change-of-control payments — private companies can cleanse it with a properly run shareholder vote, but only if someone remembers, early. § 382 limits the acquirer's use of the target's NOLs after an ownership change. And escrows and earnouts implicate § 453 installment reporting and imputed interest.

Sablewood's acquirer opens with an asset purchase. Sablewood's counsel explains that the double layer plus the loss of QSBS would cost the founders roughly a third of their proceeds, and the parties land on a stock purchase with an enhanced indemnity and a representations-and-warranties insurance policy. The structure and the diligence live in Mergers and Acquisitions: A Comprehensive Guide from Letter of Intent to Closing, Conducting Merger and Acquisition Due Diligence: A Practical Checklist, and The Mergers and Acquisitions Toolkit. What the founders do with the proceeds afterward — and how to move QSBS into trusts before an exit to multiply the exclusion — belongs to The Estate Planning and Wealth Transfer Toolkit and Wills, Trusts, and Probate: A Comprehensive Estate Planning Guide. That planning has to happen before the letter of intent, not after.

Pillar 9 — Tax-exempt organizations

A different regime entirely, and one many businesses touch — as founders of a foundation, as sponsors, or as donors.

26 U.S.C. § 501(c)(3) exempts corporations organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes. Two tests, from Treas. Reg. § 1.501(c)(3)-1: the organizational test (the charter must limit purposes to exempt ones and dedicate assets to charity on dissolution) and the operational test (the organization must actually operate primarily for exempt purposes). Recognition normally comes by filing Form 1023 (or the streamlined 1023-EZ).

Three prohibitions define the boundary. Private inurement — no part of net earnings may benefit an insider, and this one is absolute. Private benefit — more than incidental benefit to private interests defeats exemption. And political campaign intervention — an absolute ban on supporting or opposing candidates. Lobbying is limited, not banned, and a § 501(h) election substitutes bright-line expenditure ceilings for the vague "substantial part" test. Between total revocation and a slap on the wrist sit the § 4958 intermediate sanctions, excise taxes on excess-benefit transactions imposed on the insider and on the managers who approved them.

Even exempt organizations pay tax on unrelated business taxable income (§§ 511–514) — income from a regularly carried-on trade or business not substantially related to the exempt purpose, with § 512(a)(6) requiring separate "siloing" of each unrelated trade or business. Whether the organization is a public charity or a private foundation under § 509(a) determines which Chapter 42 excise taxes, deduction limits, and distribution requirements apply. Annual reporting is on Form 990, which is public — for many nonprofits it is the most-read document they produce.

Start with Forming and Operating a Nonprofit: A Comprehensive Guide to Tax-Exempt Status, file with Applying for Tax-Exempt Status: A Form 1023 Checklist, and map the whole sector with The Nonprofit Legal Toolkit.

Pillar 10 — Controversy, penalties, and collections

Assessment and the clock. The IRS generally has three years from filing to assess (§ 6501(a)), six years if the return omits more than 25% of gross income (§ 6501(e)), and forever if the return is fraudulent or never filed. That last point deserves emphasis: an unfiled return means an open year, permanently.

The examination path. Correspondence audit, office audit, or field examination; information gathered by Information Document Request and, if necessary, administrative summons under § 7602. If the examiner proposes adjustments, the taxpayer receives a 30-day letter and may protest to the IRS Independent Office of Appeals, whose mandate is to settle based on the hazards of litigation — and which settles the great majority of what reaches it. If no agreement, the Service issues a statutory notice of deficiency under § 6212 (the "90-day letter"), and the taxpayer may petition the United States Tax Court under § 6213 without paying first. That prepayment forum is a genuine advantage. The alternative is to pay in full and sue for refund in district court or the Court of Federal Claims — full payment being a jurisdictional prerequisite under Flora v. United States, 362 U.S. 145 (1960).

Penalties. § 6651 for failure to file and failure to pay; § 6662's 20% accuracy-related penalty for negligence, substantial understatement, or substantial valuation misstatement; § 6663's 75% civil fraud penalty; § 6672's Trust Fund Recovery Penalty (Pillar 6); § 6707A for undisclosed reportable transactions. The general defense is reasonable cause and good faith under § 6664(c) — and reliance on a competent professional given complete information is the paradigm case. Criminal exposure begins at § 7201 (evasion), § 7202 (failure to collect or pay over), and § 7206(1) (false return); the line between civil fraud and criminal referral is thinner than most business owners imagine.

Collections. A federal tax lien arises automatically on assessment, demand, and nonpayment (§ 6321), attaching to all property, and it becomes effective against most third parties when the Notice of Federal Tax Lien is filed (§ 6323). The IRS may levy under § 6331. Two due-process valves exist — a Collection Due Process hearing on lien filing (§ 6320) or before levy (§ 6330), each with a strict 30-day window and Tax Court review. And two resolutions: an installment agreement (§ 6159) or an offer in compromise (§ 7122), the latter accepted mainly for doubt as to collectibility, computed against reasonable collection potential.

Run any live matter with Handling an IRS Audit and Tax Controversy: A Comprehensive Guide. When the examination turns criminal, or when the summons comes from a grand jury rather than a revenue agent, stop and read Responding to a Government Subpoena or Investigation: A Practical Checklist and White-Collar Crime and Corporate Criminal Liability: A Comprehensive Guide before another word is said to an agent. When the tax debt is simply larger than the business, the treatment of priority and trust-fund taxes in insolvency is mapped in The Bankruptcy and Restructuring Toolkit.

Sablewood, end to end: the worked example with numbers

Pull the running example together, because the pillars only make sense when you can see them compound in one company.

Year 0 — formation. Sablewood Robotics, Inc. incorporates in Delaware and qualifies to do business in Colorado. Dara and Miguel each buy 4,000,000 shares of common at $0.0001, a $400 purchase, subject to four-year vesting with a one-year cliff. Both file 83(b) elections on day 12 — well inside the 30-day window — and each reports $0 of spread (fair market value equals price paid). Their capital-gains holding period and their § 1202 clock both start now. Default federal classification: C corporation (a Delaware Inc. is a per se corporation under Treas. Reg. § 301.7701-2(b); there is no box to check). No S election is made — the company plans to issue preferred stock, which would violate the one-class-of-stock rule of § 1361(b)(1)(D).

Counterfactual. Had they skipped the 83(b), and had the stock been worth $1.50 a share by the second vesting tranche, each founder would have recognized ordinary income of roughly $1,500,000 on 1,000,000 vesting shares — cash tax on stock they could not sell. The cost of avoiding it was a one-page election and a certificate of mailing.

Years 1–3 — losses and equity. Sablewood raises a priced Series A, hires 22 employees, and loses money. Its § 11 liability at the 21% rate is $0, and it accumulates net operating losses that can offset only 80% of future taxable income under § 172 and that will be limited under § 382 on the eventual ownership change. It adopts an equity incentive plan and obtains an annual 409A valuation; every option is struck at or above the appraised fair market value, so no grant is deferred compensation under § 409A. Engineers get ISOs under § 422 (with the $100,000 annual vesting limit tracked, and an AMT warning delivered in writing before exercise); the two outside advisors get NSOs, because ISOs are for employees only.

Year 2 — the payroll mistake. The "contract" firmware engineer is paid $180,000 a year on a 1099. He works full time, on Sablewood laptops, in Sablewood's shop, on Sablewood's schedule. He is an employee under the common-law control test. When he later files for unemployment, the state agency's finding triggers a federal exam. Sablewood owes back income-tax withholding, both halves of FICA, FUTA, state unemployment, and penalties — and because withheld trust-fund amounts were never collected in the first place, its finance lead spends a very bad week learning what "responsible person" means under § 6672. Section 530 relief is argued but is weak: Sablewood cannot show a reasonable basis, and its treatment of comparable workers was not consistent.

Year 3 — the state mess. Sablewood has shipped robots into thirty states and hired remote engineers in Texas and Georgia. Under Wayfair it has blown through economic-nexus thresholds in eleven states where it never registered and never collected sales tax. P.L. 86-272 does not help: it shields only net income tax, only for solicitation of orders for tangible personal property — and it does nothing at all for sales tax, which is the actual exposure. Because no returns were filed, the statute of limitations never began to run in most of those states. The remote hires independently create income-tax, franchise-tax, and withholding nexus. The company enters voluntary disclosure agreements in each state, limiting lookback and abating penalties — but only because it moved before the states did, and before the buyer's diligence did.

Year 5 — the exit. A strategic acquirer offers $60,000,000. It opens with an asset purchase: it wants a stepped-up basis under § 1060 and 15-year goodwill amortization under § 197. Sablewood's counsel models both structures:

Asset sale Stock sale
Corporate-level tax (21% on gain) Yes — roughly $12.6M on a near-zero-basis $60M gain None
Shareholder-level tax on proceeds Yes — liquidating distribution taxed again under § 331 Single layer under § 1001
§ 1202 QSBS exclusion available No — § 1202 excludes gain on the sale of stock, not assets Yes, if the requirements are met
Buyer basis step-up Yes No (carryover basis inside the target)
Buyer inherits unknown liabilities Largely no Yes

The asset structure would cost the founders roughly a third of their proceeds — the corporate 21% layer, then tax again on the way out, with the QSBS exclusion destroyed. The parties land on a stock purchase, priced to reflect the buyer's lost step-up, with an enhanced indemnity and a representations-and-warranties insurance policy bridging the risk the buyer would otherwise have refused to take.

Three cleanup items land in the same month. § 280G: the CEO's change-of-control package is a parachute payment; because Sablewood is private, the excise tax and lost deduction are cleansed by a properly conducted shareholder vote — run early, with correct disclosure, not on the eve of closing. § 382: the NOLs the buyer was underwriting are sharply limited by the ownership change, and the purchase price is adjusted. Estate planning: the founders wanted to gift QSBS into non-grantor trusts to multiply the per-issuer cap — but that had to happen before the letter of intent, when the stock was still cheap and the sale was not yet a near-certainty. One founder did it. One did not. The difference is measured in millions.

Every one of those events was decided years before it mattered, in a document nobody thought was a tax document.

The landscape as a working checklist

A gated audit. Do not pass a gate with an open item.

Gate 1 — Formation and classification

  • [ ] State-law entity chosen and formed; federal tax classification consciously selected, not defaulted into.
  • [ ] Form 8832 and/or Form 2553 filed within the applicable window; confirmation letter in the corporate record.
  • [ ] EIN obtained; accounting method and tax year set.
  • [ ] If S corp: all shareholders eligible; single class of stock confirmed in the charter and in every side letter.
  • [ ] If partnership/LLC: operating agreement includes tax distributions, a § 704(b) allocation regime, and a named partnership representative.

Gate 2 — Founders and equity

  • [ ] Founder stock issued at formation; 83(b) elections filed within 30 days, with proof of mailing retained.
  • [ ] Equity incentive plan adopted; option grants approved by the board with contemporaneous minutes.
  • [ ] 409A valuation current (within 12 months, or after any material event); no option priced below fair market value.
  • [ ] QSBS eligibility documented at each issuance: C corp status, original issuance, gross-asset test, active business.
  • [ ] ISO $100,000 limit tracked; employees warned about AMT before exercise.

Gate 3 — People and payroll

  • [ ] Every worker classified under the common-law control test and the applicable state test; the file shows the analysis.
  • [ ] Payroll provider engaged; deposits made on schedule; Forms 941, 940, W-2, and 1099-NEC filed on time.
  • [ ] Responsible persons identified and aware of § 6672 exposure.
  • [ ] Contractor agreements consistent with contractor treatment in fact, not just in the caption.

Gate 4 — Multistate

  • [ ] Economic nexus reviewed for sales tax in every state of sale; registrations current.
  • [ ] Income/franchise/gross-receipts nexus reviewed, including for every remote employee.
  • [ ] Marketplace facilitator obligations confirmed for each platform.
  • [ ] Any historical exposure resolved through voluntary disclosure before diligence surfaces it.
  • [ ] PTET election evaluated annually.

Gate 5 — Transactions and exit

  • [ ] Structure modeled both ways (asset vs. stock) with the after-tax proceeds to each seller shown.
  • [ ] QSBS holding periods and per-issuer caps confirmed against issuance-date rules; § 1045 rollover considered if short.
  • [ ] § 280G analysis run and cleansing vote scheduled, if applicable.
  • [ ] § 382 impact on NOLs modeled.
  • [ ] Estate and gift planning done before the LOI.

Gate 6 — Compliance and controversy

  • [ ] All returns filed — an unfiled return leaves the year open forever.
  • [ ] Positions supported by contemporaneous documentation and, where warranted, disclosure.
  • [ ] Deadlines calendared: 30 days for a protest or a CDP request; 90 days to petition the Tax Court.
  • [ ] Privilege considered before the first document goes out the door.

Primary Authority

Internal Revenue Code (Title 26, U.S. Code)

  • § 11 — corporate income tax rate
  • §§ 61, 162, 172, 197 — gross income; ordinary and necessary business expenses; net operating losses; amortization of intangibles
  • § 83 — property transferred in connection with the performance of services; § 83(b) election
  • §§ 199A, 1202, 1045, 1244 — pass-through deduction; qualified small business stock; QSBS rollover; ordinary loss on small business stock
  • §§ 301, 316, 331, 336, 338, 351, 356, 368, 382 — corporate distributions and dividends; liquidations; deemed asset sales; incorporation; boot; reorganizations; loss limitation after ownership change
  • §§ 409A, 422, 280G — nonqualified deferred compensation; incentive stock options; golden parachutes
  • §§ 701, 704, 707, 721, 731, 752, 754 — partnership taxation (Subchapter K)
  • §§ 1361–1379 — S corporations (Subchapter S), including § 1362 (election) and § 1374 (built-in gains)
  • §§ 1401–1402, 1411 — self-employment tax; net investment income tax
  • §§ 3101–3128, 3301–3311, 3402 — FICA; FUTA; income tax withholding
  • § 1060 — allocation of purchase price in an applicable asset acquisition
  • §§ 501(c)(3), 509, 511–514, 4958 — tax exemption; public charity status; unrelated business income; intermediate sanctions
  • §§ 6212, 6213, 6320, 6321, 6323, 6330, 6331, 6501, 6651, 6662, 6663, 6664, 6672, 6707A, 7122, 7201, 7206, 7602, 7701(o) — deficiency and Tax Court procedure; liens and levies; limitations; penalties; collection alternatives; criminal provisions; economic substance

Regulations and administrative guidance

  • Treas. Reg. § 301.7701-2, -3 — entity classification; the check-the-box rules
  • Treas. Reg. § 1.501(c)(3)-1 — organizational and operational tests
  • Treas. Reg. § 1.409A-1(b)(5)(iv) — stock-right valuation safe harbors
  • Treas. Reg. § 1.368-1 — continuity of interest and continuity of business enterprise
  • Rev. Proc. 93-27 and Rev. Proc. 2001-43 — profits interests
  • Rev. Rul. 74-44 and Rev. Rul. 87-41 — S corporation reasonable compensation; worker classification factors
  • Section 530 of the Revenue Act of 1978 — worker classification safe harbor

Cases and other federal law

Secondary Sources

  • Bittker & Eustice, Federal Income Taxation of Corporations and Shareholders — the reference work for Subchapter C.
  • McKee, Nelson & Whitmire, Federal Taxation of Partnerships and Partners — the reference work for Subchapter K.
  • Bittker & Lokken, Federal Taxation of Income, Estates and Gifts.
  • Hellerstein & Hellerstein, State Taxation — the standard treatise on state and local tax.
  • IRS Internal Revenue Manual (examination, Appeals, and collection procedures).

Related UpLaw Resources

Related Guides & Articles

Related Checklists

Related Toolkits

This toolkit is general legal information from UpLaw (uplaw.us), not legal advice, and does not create an attorney-client relationship. Tax law is federal, but entity law and state and local tax vary by state, and both change frequently — dollar thresholds and effective dates in particular are moving targets. Verify current requirements and consult qualified tax counsel or a CPA before acting.