Moving To or From Illinois: Tax Guide

Residency is about domicile, not days

Illinois defines a resident as an individual in Illinois for other than a temporary or transitory purpose, or domiciled in Illinois but absent for a temporary or transitory purpose. That second limb is the one that matters when people move. Domicile is where you intend your permanent home to be, and the rule is that you keep your existing domicile until you establish a new one. Buying a condo in Florida does not end an Illinois domicile; making Florida your permanent home does.

There is no 183-day safe harbor in the Illinois statute. Some states have one; Illinois relies on facts and circumstances, which means the question is decided on evidence rather than arithmetic. That cuts both ways — there is no bright line to fail, and no bright line to hide behind.

What actually gets looked at

Nobody publishes an official checklist, but the factors that turn up in residency disputes are consistent, and they are the ordinary indicators of where a person's life is centered:

• Where you spend your time, and where your family lives;
• Driver's license and vehicle registration;
• Voter registration and where you actually vote;
• The address on bank accounts, brokerage accounts, insurance and professional licenses;
• Where your doctors, dentists and other professional relationships are;
• Property ownership and — critically — which property carries a homestead exemption.

That last one deserves emphasis because it is a self-inflicted wound. The Illinois General Homestead Exemption requires by statute that the property be occupied as your principal residence. Continuing to claim it after you claim to have left is a contradiction recorded in the county's own files, and it is the easiest possible thing to check. The same goes for keeping an Illinois driver's license "for convenience".

Part-year residents and Schedule NR

Move in or out during the year and you file Form IL-1040 with Schedule NR attached. The schedule runs two columns — everything from your federal return in Column A, and the Illinois portion in Column B — and Illinois tax is computed on the apportioned base rather than on your whole year.

What goes in Column B for a part-year resident is: all income received while you were an Illinois resident, from any source anywhere, plus Illinois-source income from the portion of the year you were not a resident. The timing of income therefore matters a great deal around a move. Exercising options, taking a bonus, realizing a capital gain or converting an IRA in January when you leave in June is a very different outcome from doing it in July.

Non-residents with Illinois-source income file the same schedule with only the Illinois-source column populated. Where you also need to know what Illinois withheld and whether it was right, the Form IL-1040 guide covers the rest of the return.

The four reciprocal states

Illinois has reciprocal agreements with Iowa, Kentucky, Michigan and Wisconsin. A resident of one of those states who works in Illinois is not taxed by Illinois on wages, salaries and tips: they file Form IL-W-5-NR with their Illinois employer, Illinois withholding stops, and they pay their home state instead. The arrangement is symmetrical, so an Illinois resident working in any of the four is not taxed there on wages either.

Two limits catch people out. First, the agreements cover wages, salaries and tips only. Business income from Illinois, rent from Illinois property, gain on Illinois real estate, and gambling and sports wagering winnings all remain Illinois-taxable regardless — Schedule NR spells out the gambling point explicitly. Second, the form is not automatic. Until IL-W-5-NR is filed, your employer must withhold Illinois tax, and recovering it means filing an Illinois return to claim it back.

Note who is not on the list: Indiana and Missouri. An Illinois resident working in Indiana pays Indiana tax and claims a Schedule CR credit against Illinois — the Illinois versus Indiana comparison covers that border in detail, including Indiana's county income taxes, which have no Illinois equivalent.

Credit for tax paid to another state

Where no reciprocal agreement applies, Schedule CR prevents genuine double taxation. An Illinois resident gets a credit for income tax paid to another state, the District of Columbia, a US territory, or a local jurisdiction in another state. The credit is limited to the lesser of the tax you actually paid there and the Illinois tax on that same income.

Because Illinois sits at 4.95%, that limit bites often. Work in a state with a higher effective rate and the excess is simply lost — not refunded, not carried forward. Work in a state with no income tax and there is nothing to credit, so Illinois takes the full 4.95%. The credit equalises to the higher of the two burdens; it never produces the lower.

Part-year residents may claim the credit only for income earned during their Illinois resident period. And there is no Schedule CR credit for wages covered by a reciprocal agreement — if a reciprocal state wrongly withheld, the remedy is a refund claim there, not an Illinois credit. Local city and county taxes in another state are the one exception where the credit does reach beyond state-level tax.

The 30-day rule for working in Illinois

Since tax years ending on or after 31 December 2020, a non-resident employee's compensation becomes Illinois-source only when the Illinois service is more than incidental and exceeds 30 working days in the year. Past that threshold, Illinois taxes the ratio of Illinois working days to total working days.

The definitions are precise. A working day excludes weekends, holidays, vacation and sick days. A day counts as an Illinois day where more duties were performed in Illinois than anywhere else that day, with travel time disregarded — or where the only service performed was traveling to an Illinois destination reached that day. Disaster-response days are excluded. The employer withholding obligation follows the same threshold, which is why a consultant on a long Chicago engagement suddenly appears on an Illinois payroll register. The employer-side consequences run through the remote work page.

Is Illinois a good move, tax-wise?

The honest answer splits by stage of life, and the split is sharper in Illinois than in most states.

For someone still working, Illinois is unremarkable to poor. The 4.95% flat rate looks low next to a top marginal rate elsewhere, but it applies to a much broader base: there is no Illinois standard deduction, no itemizing, and only a small personal exemption that disappears above $250,000 of AGI. Add property taxes among the highest in the country and combined sales tax reaching 10.50% in Chicago — the sales tax calculator has the rates — and the total burden is meaningfully higher than the income tax rate alone suggests. Run your own number on the salary after taxes page before drawing conclusions.

For someone retired, Illinois is genuinely among the best states in the country. Federally taxed retirement income is subtracted in full on Line 5 — pensions, 401(k) and IRA distributions, Social Security, railroad retirement — with no income limit, no partial exclusion and no age test. A retiree with $90,000 of pension and withdrawals can have an Illinois income tax bill of zero. That is a very different proposition from the working-age picture, and it is worked through on the Illinois retirement taxes page.

One item cuts the other way for larger estates: Illinois levies an estate tax with a $4,000,000 exclusion that is not indexed for inflation, and has not been since 2013. There is no portability between spouses as there is federally. For an estate comfortably above that figure, the planning consequences of Illinois domicile can dwarf every income tax consideration on this page.