The Mobile Workforce State Income Tax Simplification Act of 2026 restricts how states can tax employees who work in multiple states. Under the bill, employees can only be taxed on their wages by their home state or by any state where they perform work for more than 30 days in a calendar year. The legislation applies to most workers but excludes professional athletes, entertainers, production employees working on film or television projects, and certain high-profile public figures who are paid per event. Employers can rely on employees' self-reported work locations to determine tax obligations, though companies with time-tracking systems can use those records instead, and employers are protected from penalties if they follow these rules in good faith. The law takes effect on January 1 of the second calendar year following enactment, meaning it would apply starting in 2028 if passed in 2026.