Football Players | Nonresident Income Tax Filing

The Kansas City Chiefs are narrowly favored in their season opener against the Los Angeles Chargers on Friday, but California is already a loser regardless of how Jim Harbaugh’s squad performs in São Paulo.

The National Football League is seeking to expand its international fan base, featuring seven international games this season, starting with the Chiefs-Chargers week one matchup in Brazil. (An additional three games will be played in London, plus one each in Berlin, Dublin, and Madrid.)

When the Kansas City and Los Angeles squads face off in São Paulo, the players will owe Brazil’s nonresident income tax on the share of income they earned there, while California will lose out on the nonresident income taxes that Chiefs players ordinarily would have remitted in what is nominally a Chargers home game.

The two teams’ players will owe an estimated $1.04 million to Brazil, for which they will receive an offsetting credit against their US federal income taxA tax is a mandatory payment or charge collected by local, state, and national governments from individuals or businesses to cover the costs of general government services, goods, and activities. liability. Brazil levies a flat 15 percent tax on nonresidents’ income earned in the country, which is lower than the marginal rate on that income that any NFL player will face under the US federal income tax. Therefore, while some of players’ tax liability shifts from the US to Brazil, net liability does not increase.

If this were an ordinary Chargers home game, however, Chiefs players would spend about three “duty days” in California, paying California income tax for that period. Without that trip to Los Angeles, the state of California loses out on about $462,000 in state income tax collections from the Chiefs players alone—to say nothing of income tax from coaches and staff, broadcast crews, and the like, or the sales and other tax revenue generated from fans.

And while Chiefs players will still owe Missouri $175,000 in income taxes on the time they spend in Brazil, that represents a savings of $287,000 compared to playing in California.

Let’s take a quick look at how this works—and how it matters for everyday business travelers, too, not just professional athletes.

The basic rule of income tax liability is that you owe income taxes where you live and where you work, but with a credit to avoid double taxationDouble taxation is when taxes are paid twice on the same dollar of income, regardless of whether that’s corporate or individual income..

States typically have special rules for athletes, colloquially called “jock taxes” (even though it’s still just the income tax), using “duty day” calculations to account for the way players earn income. NFL players typically have about 200 duty days across the season and usually spend three duty days in another state when playing an away game, meaning that 1.5 percent of their compensation (3/200) is allocated to that state. For those of us who don’t play professional sports, the share of days spent in the state is typically used.

Your home state is entitled to tax all your income from all sources (wages, investment income, etc.), wherever earned, though in practice, many states exclude certain classes of income (e.g., retirement income). When someone from Kansas City, Missouri—whether they’re a Chiefs player, an accountant, or a plumber—works in another state, they owe Missouri income tax on the out-of-state income, even though the other state may also tax it. A credit is then taken for taxes paid to the other state, but only up to the amount owed in one’s home state on that income. Consequently, if the other state has higher taxes, net liability increases.

Other states are entitled to tax you where you work. When someone from Missouri works a few days in California, they owe California income taxes on the share of income they earned in California. If Patrick Mahomes, with annual compensation of $28.06 million, must attribute 1.5 percent of his earnings to California, then he pays the state 1.5 percent of what he’d owe on $28.06 million earned in California. That works out to about $55,242.

Since Mahomes would only have to pay Missouri $19,760 on that share of his income, he’s $35,482 in the red by playing a game in the Golden State. He takes $19,760 as a credit against his Missouri taxes, but the rest represents additional taxation. Conversely, if the Chargers played an away game against the Chiefs, this would result in no additional tax liability, since Missouri’s taxes (which would be credited against California’s) are so much lower than the amount already owed to California.

By playing in Brazil, Mahomes and his teammates avoid California’s high taxes. They still pay Missouri about $175,000 in aggregate for those duty days (and about $11.7 million across the season before credits for taxes paid to other states), but they avoid the extra liability that comes from playing in high-tax California.

Incidentally, if the Chiefs were based in California instead of Missouri, the roster’s home state tax liability for the 2025 season would be about $30.8 million, not the $11.7 million (less credits) they’ll pay to Missouri.

All of this is complex. It requires filing tax returns in multiple states, with many states requiring filing and remittance after even a single day spent in the state—no matter how little income is earned. Mahomes can afford an excellent tax preparer. But for the rest of us, that’s a real hassle, often over trivial amounts of tax liability.

Jock taxes are likely here to stay. But for the rest of us, lawmakers can make life easier—at a cost of very little revenue—by adopting reasonable thresholds before a nonresident owes income tax.