Marital status sits at the foundation of nearly every individual return. It determines the filing status available to the taxpayer, the size of the standard deduction, the width of the rate brackets, the phase-out thresholds for dozens of credits, and in some cases whether a benefit is available at all — yet it is not a matter of taxpayer election. It is a question of law, determined on the last day of the tax year, under rules that intersect with state domestic relations law, federal recognition standards, and a set of statutory exceptions a preparer must be able to apply from memory.

This course examines marital status as a working determination rather than an intake checkbox, then applies it to three areas where marital status changes the outcome in ways that surprise both taxpayers and preparers: the adoption credit, the moving expense deduction, and the exclusion of gain on the sale of a principal residence. Each area was touched, directly or indirectly, by the One Big Beautiful Bill Act (OBBBA), enacted July 4, 2025. The course also covers the compliance obligations attached to every one of these determinations: the preparer penalty regime under §§6694 and 6695, the due diligence requirements of §6695(g), and the taxpayer data safeguarding duties imposed by §7216 and the Gramm-Leach-Bliley Act.