Work in Missouri, Live in Illinois: How Taxes Work

Reciprocity

Do Illinois and Missouri Have a Tax Reciprocity Agreement?

No. Illinois publishes its reciprocal-agreement list in the Department of Revenue employer withholding guidance, and Missouri is not on it. Illinois has reciprocal compensation agreements only with Iowa, Kentucky, Michigan, and Wisconsin. A resident of one of those four states can file Form IL-W-5-NR to exempt themselves from Illinois withholding when working in IL. A Missouri resident cannot, and neither can an Illinois resident who commutes the other way to a Missouri employer.

The practical effect: Missouri gets the first claim on wages earned inside its borders. Your MO employer must withhold Missouri income tax on the paycheck. Illinois then taxes you as a resident on all your income from every source, and the Schedule CR credit on IL-1040 for tax paid to other states prevents the same dollars from being taxed at both states' full rates.

Filing Obligations

Which Returns Do I File as an IL Resident Working in MO?

You file two state returns each year. The Missouri nonresident return uses Form MO-1040 (the long form) together with Form MO-NRI, which calculates your Missouri income percentage. The Illinois resident return uses Form IL-1040, and the credit for the Missouri tax you paid is claimed on Illinois Schedule CR.

File the Missouri return first. You need the final Missouri tax figure to complete the Illinois Schedule CR calculation. The Missouri instructions require nonresidents with Missouri-source income to complete Part A, Line 1, Part B, and Part C of Form MO-NRI, and to attach the federal return along with W-2s and 1099s.

Both returns share the April 15 due date. Missouri accepts a federal extension for the state return. Illinois grants an automatic six-month filing extension, but the tax itself is still due by the April deadline. Estimated payments or a check with the extension request avoid late-payment interest.

Illinois Credit

How Does IL Schedule CR Prevent Double Taxation?

Schedule CR (Credit for Tax Paid to Other States) exists so an Illinois resident is not taxed twice on the same dollar of income. The Illinois Department of Revenue describes it as a credit for income taxes paid to other states on income received while an Illinois resident. Publication 111 walks through the line-by-line calculation and explains that the credit is capped at the lower of the actual tax paid to the other state or the Illinois tax on that same income.

Because Illinois uses a flat 4.95 percent rate and Missouri's top rate is 4.7 percent for 2025, the two rates land close together at higher incomes. On lower and middle incomes the effective Missouri rate can fall well below Illinois's flat rate. The gap is what causes many Illinois residents who work in Missouri to still owe Illinois a modest balance after the credit, even when Missouri tax was withheld from every paycheck.

You must have filed a required Missouri return to claim the credit. Illinois asks you to keep the Missouri return with your records rather than attach it, but the state may request the return during a review. Publication 111 walks through common part-year and full-year scenarios and shows the Column A and Column B calculations used on the schedule.

Only qualifying taxes count. Illinois Publication 111 limits the credit to income taxes paid to another state, the District of Columbia, or a US territory. City wage taxes and other subdivision income taxes generally qualify; sales, use, and property taxes do not.

Employer Withholding

How Should My Missouri Employer Withhold?

Your Missouri employer withholds Missouri state income tax on wages you earn for services performed inside Missouri. Missouri uses the location where the work is performed to determine withholding, not where the employee lives. There is no IL-W-5-NR equivalent you can hand your Missouri employer to skip Missouri withholding, because Missouri is not a reciprocity state for Illinois.

Because no Illinois tax is withheld from that paycheck, you often owe Illinois a balance at filing time even after applying the Schedule CR credit. To smooth the cash flow:

• Make quarterly IL-1040-ES estimated payments if you expect to owe Illinois more than $1,000 in state tax after credits and withholding.
• If you have a second job in Illinois, ask that employer to withhold extra Illinois tax on Form IL-W-4 to cover the gap on your MO wages.
• Review the balance annually. Bracket creep, bonus timing, and Illinois exemption changes can all shift the residual balance.

If you also perform work inside St. Louis city limits or Kansas City limits, an additional 1 percent local earnings tax applies on wages earned in those cities. That is a separate local return, not a state return, and it is not creditable against Illinois state tax the same way state-level Missouri tax is.

Remote Work

What If I Work Remotely from Illinois for a Missouri Employer?

Missouri applies a physical-presence sourcing rule for wages. If you perform the work from your Illinois home, the wages for those days are Illinois-source income, not Missouri-source income, and Missouri should not withhold tax on them. The Missouri Department of Revenue confirms in the 2025 MO-NRI instructions that remote work performed for a Missouri employer while the worker is physically outside Missouri is not taxable to Missouri.

The practical effect for a hybrid schedule: divide your workdays by location. Days worked at the Missouri office are Missouri-source. Days worked from your Illinois home are Illinois-source. Report only the Missouri-source portion on Form MO-NRI Part B, and let Illinois tax the rest through IL-1040.

Keep a workday log. In an audit either state may ask you to prove where you were on specific days. Calendar exports, badge-swipe records, corporate travel systems, and virtual private network login records all serve as evidence of days worked inside or outside Missouri.

Worked Example: IL Resident Earning $75,000 in Missouri

Single filer, all wages sourced to Missouri, using verified 2025 Missouri tax chart and Illinois 4.95 percent flat rate; ignores federal-linked exemptions for simplicity

Mid-Year Move

What If I Moved Between Illinois and Missouri During the Year?

If you changed your permanent residence between Illinois and Missouri during the tax year, file a part-year return in each state. Illinois uses Schedule NR to allocate income between resident and nonresident portions of the year on IL-1040. Missouri uses the same Form MO-1040 with MO-NRI to report part-year residency, allocating income earned as a resident and as a nonresident.

During the months you were an Illinois resident, IL taxes all your income at the flat rate, with the Schedule CR credit still available for tax paid to Missouri on Missouri-source wages during that period. During the months you were a Missouri resident, MO taxes all your income at the graduated Missouri rates, and IL taxes only IL-source wages, if any, from that later period.

Document the exact move date. Utility hookups, a signed lease, driver's license changes, and voter registration updates all serve as evidence for either state should the timing be questioned.

Withholding Errors

What If My Employer Withheld Only Illinois Tax by Mistake?

If a Missouri employer treated you as an Illinois employee and withheld only Illinois tax, you will owe Missouri a large balance when you file MO-1040. Report the full Missouri source wages on MO-NRI, calculate the Missouri tax, and pay the shortfall with the return. Missouri assesses interest on unpaid balances from the original due date, so filing and paying promptly limits the cost.

On the Illinois side, you already paid IL tax through withholding. When you file IL-1040 and complete Schedule CR for the Missouri tax you just paid, the credit reduces or zeros your Illinois tax on those Missouri-source wages, and the Illinois withholding becomes an overpayment that Illinois refunds. Ask your Missouri employer to start withholding Missouri tax immediately going forward so the same mismatch does not repeat next year.

Also update the local piece. If your Missouri work location is inside St. Louis or Kansas City, the 1 percent earnings tax should have been withheld separately. If it was missed, contact the city's collector of revenue to arrange payment and get on the right track for future paychecks.

Local Taxes

Do St. Louis, Kansas City, or Illinois Local Taxes Apply?

Missouri has two cities with an earnings tax: St. Louis and Kansas City. Both impose a 1 percent tax on wages earned for services performed inside the city limits, regardless of the employee's state of residence. If your Missouri office sits inside either city, that 1 percent applies to you as an Illinois resident, and your employer should withhold it. The tax is remitted to the city's collector of revenue, not to Missouri or Illinois.

Illinois does not have a general municipal income tax. Cook County and the City of Chicago collect various fees and specific-purpose taxes, but no city or county in Illinois levies a broad wage or income tax comparable to the St. Louis or Kansas City earnings tax. Your Illinois obligation as a resident is the state IL-1040 alone at the flat 4.95 percent rate.

Whether the St. Louis or Kansas City 1 percent counts toward Illinois's Schedule CR credit is worth checking against current Illinois Publication 111 guidance, because the schedule allows credit for taxes paid to political subdivisions of another state. For more on the broader network of state-to-state deals, see our state reciprocity agreements list.