Every employer in the country completes a federal immigration form for every employee, and most complete it wrong. This article explains what Form I-9 actually requires, why the most common errors have nothing to do with anyone's immigration status, and how a routine paperwork audit produces six-figure penalties at companies that never knowingly hired anyone unauthorized. It covers the three-day rule, the document list and why an employer may not choose from it, reverification and when it is prohibited, and the retention formula almost nobody applies correctly. It explains E-Verify — where it is required, what a tentative nonconfirmation means, and the conduct that turns a compliance tool into a discrimination claim. It walks through a worksite inspection from the notice through the fines, and explains the anti-discrimination provision that punishes employers for asking for too much documentation. Readers finish knowing what to fix before an auditor arrives.