Proposed Tax Law Sets 30-Day Rule for Multi-State Workers, Kicks In 2027

If you’re one of the millions of people whose job now involves crossing state lines—whether you’re a traveling consultant, a regional sales manager, or just working remotely from the cabin for a few weeks—this bill is a big deal for your tax life. The Mobile Workforce State Income Tax Simplification Act of 2025 is trying to clean up the messy rules about which states can actually tax your income and require your employer to withhold money from your paycheck. The core idea is simple: only two places get a cut—the state where you live (your residence) and any other state where you physically work for more than 30 days during the year (SEC. 2).

The 30-Day Rule: Cutting the Tax Paperwork

Right now, some states have aggressive rules, demanding you file a tax return and pay taxes if you spend even one day working there. That means if you live in New Jersey but have five meetings in five different states over the year, you might have to file six state tax returns. Nobody has time for that. This bill cuts through the noise by establishing a clear 30-day threshold. If you spend 30 days or less working in a state outside your home state, that state generally cannot tax your income, nor can they force your employer to withhold taxes (SEC. 2). This is huge for simplification, especially for the average mobile professional who might do a handful of trips a year. The catch? The whole thing doesn't even kick off until January 1st of the second full calendar year after the bill becomes law, meaning we’re likely looking at 2027 before these changes hit your pay stub (SEC. 3).

The Employer’s Dilemma: Trust vs. Tech

For employers, the bill offers a practical path forward. They can generally rely on the information you give them annually about where you plan to work, which simplifies payroll immensely (SEC. 2). They are protected from penalties as long as they don't know you're lying or conspiring to cheat. However, if your company uses a daily time and attendance system that tracks your location (think GPS or specific clock-in/out apps), they must use that data to figure out where you worked. They can’t just rely on your estimate anymore if they’ve invested in the tracking tech. This means if you’re tracked, you better make sure you clock out before you hit that 31st day in a high-tax state, or the withholding starts immediately, retroactive to Day 1 (SEC. 2).

The Fine Print: Who Gets Left Out?

While this bill simplifies life for most white-collar and trade workers who travel, it explicitly excludes a few groups. If you are a professional athlete, a professional entertainer, or a qualified production employee (think film crews or theater casts paid per event), you are still stuck in the old, complicated multi-state tax world (SEC. 2). Essentially, the most high-profile, high-earning mobile workers—the ones who often deal with the most complex tax situations—don't get the benefit of the 30-day rule. For them, it’s business as usual: complex filings in every state they perform in.

The Weird Math of a ‘Day’

The bill also introduces a surprisingly detailed and slightly confusing definition of what counts as a “day” for the 30-day test. A “day” is defined as when you perform more of your work duties in one state than any other state. But here’s the kicker: if you work in your home state and only one other state on the same day, the rules say you are considered to have done more work in that other state for the purpose of counting days. This special rule means even a short trip out of state could count as a full day toward that 30-day limit, which might make it easier for states to hit the threshold and claim tax jurisdiction. It’s a small detail, but it shows how complicated simplification can get when you’re dealing with tax jurisdiction.