Moving from Illinois to Missouri: Residency, Taxes, and What to Prove

In Illinois

Illinois has no statutory day-count test to trip, so a travel nurse not domiciled in Illinois does not become an Illinois resident merely by crossing a day threshold on a long assignment. What creates exposure instead is the temporary or transitory question and the 100.3020(f) presumptions: an assignment structured as a series of renewals that keeps a nurse in Illinois more than nine months of a year, or more days than in any other state, supports a presumption of residency that must be rebutted by clear and convincing evidence, and the permanent or temporary nature of the work assignment is named in the rule as relevant evidence. The more common Illinois exposure is the reverse pattern, where a nurse claims a Florida or Texas tax home but actually lives in and pays Illinois-area rent for most of the year; Illinois-source wages for days actually worked in Illinois are taxable to any nonresident nurse regardless of claimed tax home.

In Missouri

Missouri has no statutory carve-out for travel nurses distinct from its general residency test; the federal tax-home question under IRS Publication 463 governs stipend treatment, and Missouri residency then follows the statutory domicile/183-day framework like any other taxpayer. Missouri's major hospital systems in St. Louis, Kansas City, and Springfield draw a steady stream of travel nursing assignments, and a nurse who claims an out-of-state tax home while actually renting and living in Missouri most of the year risks the same tax-home disallowance pattern documented nationally on travel-nurse forums, which would also expose them to Missouri's statutory 183-day resident test if they maintain a Missouri residence.

In Illinois

Illinois taxes nonresident professional athletes on a duty-day basis: Illinois-source income equals total compensation multiplied by the ratio of duty days in Illinois (games, practices, mandatory team functions) to total duty days for the season; mere travel through Illinois without a game or team event does not create a duty day. This applies to visiting teams playing the Bears, Bulls, Blackhawks, White Sox, and Cubs, and Illinois is regarded by practitioners as an aggressive, well-enforced jock-tax state that historically extended the tax reciprocally to any state that taxed Illinois-based athletes.

In Missouri

Missouri is home to the Chiefs (whose stadium sits in Missouri just across the state line from Kansas), Royals, Cardinals, and Blues. Missouri applies duty-day apportionment to nonresident professional athletes' income earned from games and team activities in Missouri, consistent with how most income-tax states administer the jock tax, and Missouri-domiciled players on these teams owe Missouri tax on their full income before credits for tax paid to other states where they play road games.

In Illinois

The Illinois snowbird risk runs entirely through the 100.3020(f) presumptions, not through a day threshold. A retiree who keeps the Illinois house and spends more than nine months there risks the nine-month presumption of residency, and a former Illinois resident is presumed to still be one in the following year if present in Illinois more days than in any other state, which is a comparison a snowbird splitting a year can lose well short of any traditional threshold. The favorable counterweight is Cain v. Hamer, 2012 IL App (1st) 112833, where retirees who split time nearly evenly (1,666 Illinois days against 1,700 Florida days across 1996 through 2004) were held nonresidents, with the court weighing nexus evidence such as Florida licenses, voter registration, a Florida declaration of domicile, club spending, and credit card data showing 73% of expenditures and 61% of transactions outside Illinois. Illinois's General Homestead Exemption is a specific cross-check point if a person claims Florida domicile but keeps the Illinois exemption active.

In Missouri

A Missouri snowbird who is Missouri-domiciled and winters in Florida or Arizona only escapes Missouri tax as a nonresident if they maintain no permanent Missouri residence, keep a permanent residence in the destination state, and spend 30 days or fewer in Missouri for the entire year, which is a much tighter safe harbor than most states offer. A non-domiciled owner of a Missouri vacation or second home faces the opposite risk: maintaining a permanent Missouri residence and crossing 183 days in the state during the year makes them a Missouri statutory resident regardless of where they consider their true domicile.

In Illinois

Illinois has no convenience-of-the-employer rule. A nonresident who works remotely from another state for an Illinois-based employer is generally not taxed by Illinois on those wages, because Illinois sources employee compensation to where the services are physically performed, not to the employer's location. This makes Illinois meaningfully less sticky for remote workers than New York or a handful of other convenience-rule states.

In Missouri

Missouri has no convenience-of-the-employer rule, so a genuine Missouri resident working remotely for an out-of-state employer is taxed as a Missouri resident regardless of employer location, and a nonresident working remotely for a Missouri employer generally is not pulled into Missouri tax solely because the employer is headquartered there. The recurring Missouri-specific version of this is Kansas City and St. Louis metro commuters whose employer sits on the other side of a state line; because Missouri applies its statutory 183-day and permanent-residence test rather than a convenience rule, actual physical work location and Missouri presence both matter for anyone with ties on both sides.

In Illinois

Illinois follows the federal Servicemembers Civil Relief Act and Military Spouses Residency Relief Act. A servicemember whose home of record is Illinois remains an Illinois domiciliary for tax purposes regardless of duty station unless they take affirmative steps to change domicile, while a servicemember stationed in Illinois on orders, and their qualifying spouse, does not become an Illinois resident solely because of the posting, and military pay is not Illinois-source income for a nonresident servicemember stationed there.

In Missouri

Missouri follows the federal Servicemembers Civil Relief Act and Military Spouses Residency Relief Act. A servicemember whose home of record is Missouri remains a Missouri domiciliary and taxpayer regardless of duty station, and Missouri does not tax a nonresident servicemember's military pay solely because they are stationed in Missouri under orders. Fort Leonard Wood and Whiteman Air Force Base are the state's major installations, and a nonmilitary spouse residing in Missouri solely due to military orders can elect the servicemember's state of legal residence under MSRRA.

In Illinois

Federal law (49 U.S.C. §40116) limits states to taxing airline employee compensation only in the employee's state of residence and any state where more than 50% of pay is earned. This protects flight crew based at O'Hare or Midway who are domiciled outside Illinois from having their full compensation pulled into Illinois taxation solely because their duty station is in Illinois.

In Missouri

Federal law (49 U.S.C. §40116) limits any state's ability to tax an air carrier employee's pay to the employee's state of residence and any state where more than 50% of pay is earned. Kansas City International and St. Louis Lambert are both significant airports, and Southwest and other carriers maintain crew presence in the Kansas City metro; crew based there who are domiciled elsewhere are protected by the federal carve-out from full Missouri taxation solely because Missouri is their duty station.