The "Stop Tax Penalties on American Hostages Act of 2025" amends the Internal Revenue Code to provide significant tax relief for United States nationals who are unlawfully or wrongfully detained or held hostage abroad, along with their spouses. Its primary purpose is to ensure that these individuals are not penalized for tax-related issues while they are unable to manage their affairs. The bill introduces a new section, 7511, which mandates that the period during which an individual was detained or held hostage abroad be disregarded for determining tax deadlines, interest, penalties, and credits or refunds. This postponement applies to various tax acts and covers any interest, penalty, or additional amount accrued after the initial date of detention. The provisions also extend to the spouse of the detained individual. To identify those eligible for this relief, the Secretary of State and the Attorney General, through the Hostage Recovery Fusion Cell, are required to annually provide the Treasury Secretary with lists of U.S. nationals determined to be unlawfully detained or held hostage. The Treasury Secretary must then update databases to ensure these provisions are correctly applied. Furthermore, if any interest or penalties were assessed or collected before an individual was identified as detained, the Secretary must abate such assessments and refund any collected amounts. Beyond prospective relief, the bill establishes a program by January 1, 2026, to retroactively refund or abate penalties and interest paid by eligible individuals (or their spouses/dependents) for tax liabilities incurred during an "applicable period" from January 1, 2021, to the date of enactment . The Secretary, in consultation with the State Department and Attorney General, must identify these individuals and notify them of their potential eligibility. This program also extends the typical three-year statute of limitations for refunds to one year after notice is provided, ensuring individuals have ample time to claim their relief.