Kansas and Missouri do not have a tax reciprocity agreement. If you live in one state and work in the other, you owe income tax to both and must file two state returns each year. A credit on your home-state return prevents the same dollars from being taxed twice, but it does not eliminate the paperwork, and it will not always zero out what you owe at home.
Which State Taxes Your Income First
State income tax follows a source rule: the state where you physically perform the work gets the first claim, regardless of where you live. A Kansas resident who drives into Missouri each day owes Missouri tax on those wages. A Missouri resident commuting to a Kansas job owes Kansas tax on that income. The work state always taxes first, and you file a nonresident return there.
A Kansas resident earning wages in Missouri files Form MO-1040 with the MO-NRI schedule, which prorates Missouri tax to the portion of income earned in the state.1Missouri Department of Revenue. Nonresidents and Residents with Other State Income A Missouri resident earning wages in Kansas files Kansas Form K-40, checking the nonresident box and calculating tax only on Kansas-sourced income.2Kansas Department of Revenue. Kansas Individual Income Tax Form K-40
Both nonresident calculations start from your federal adjusted gross income, then apply the ratio of in-state income to total income. Your filing status on each state return has to match what you used on your federal Form 1040. Attach your W-2s and any documents that verify where the income was earned.
When You Have To File a Nonresident Return
Kansas requires a nonresident return if you have any income from Kansas sources. There is no minimum dollar threshold.3Kansas Department of Revenue. Frequently Asked Questions About Individual Income Missouri sets its threshold at just $600 of Missouri-source income. A short project across the line can be enough to trigger a filing obligation, so track your work days.
The Credit for Taxes Paid to the Other State
After filing the nonresident return in your work state, you file a resident return at home covering all of your income. Your home state grants a credit for the income tax you paid to the work state, which is the mechanism that prevents double taxation.
Missouri residents claim the credit on Form MO-CR, attached to Form MO-1040.1Missouri Department of Revenue. Nonresidents and Residents with Other State Income Kansas residents compute the credit using a worksheet in the K-40 instructions and enter it on Form K-40. Both states require you to attach a complete copy of the nonresident return you filed in the other state.
The credit is not a full refund of what you paid. It is capped at the lesser of two amounts: the tax you actually paid to the work state, or the tax your home state would have charged on that same income. In effect, you pay the higher of the two state rates on your cross-border earnings, but never both in full.
Missouri’s top income tax rate for 2026 is roughly 4.7%, while Kansas’s top rate reaches 5.58%. A Kansas resident working in Missouri pays Missouri’s 4.7% first, then claims the credit on the Kansas return. Because Kansas’s rate is higher, the credit covers the Missouri payment but leaves a balance owed to Kansas equal to roughly the rate difference. A Missouri resident working in Kansas pays the higher Kansas rate first, but the Missouri credit is capped at Missouri’s lower rate, so the higher Kansas rate is what you effectively bear.
The credit covers wages and other income sourced to the other state through work performed there. Passive income such as interest, dividends, or rent from property in your home state is taxed only by your resident state and does not enter the credit calculation.
Withholding and Estimated Payments
Your employer withholds state income tax for the state where you physically work, using state-specific forms. Kansas uses Form K-4; Missouri uses Form MO W-4.4Kansas Department of Revenue. Kansas Withholding Allowance Certificate K-4 If you recently started commuting across the line, check your pay stub to confirm withholding is going to the correct state.
Your employer typically will not withhold anything for your home state. The credit offsets most of what you owe at home, but if your home-state rate is higher than the work-state rate, you will still owe the difference in April. Kansas residents working in Missouri feel this most, because Kansas rates run higher than Missouri’s.
Quarterly estimated tax payments cover that gap. Kansas requires them when your expected tax after withholding and credits is $500 or more.5Kansas Department of Revenue. Kansas 2026 Individual Estimated Tax K-40ES Missouri’s threshold is much lower, at $100.6Missouri Department of Revenue. 2026 Declaration of Estimated Tax for Individuals MO-1040ES Kansas residents use Form K-40ES; Missouri residents use Form MO-1040ES. Installments are due April 15, June 15, September 15, and January 15 of the following year.7Internal Revenue Service. Individuals 2 Estimate your total home-state liability, subtract the expected credit and any home-state withholding, and divide the remainder into four payments.
Filing Order, Deadlines, and Extensions
Both Kansas and Missouri individual returns are due April 15, so you have two returns landing on the same date. Prepare the nonresident return first. The tax you calculate there is what feeds the credit on your resident return.
Both states offer six-month extensions to October 15. Kansas grants an automatic extension if you have a federal extension approved through IRS Form 4868; attach a copy of the federal extension when you file. Missouri works the same way when you have a federal extension and either expect a refund or do not expect to owe additional Missouri tax. If you do expect to owe Missouri, file Form MO-60 with payment by April 15.8Missouri Department of Revenue. Form MO-60 Application for Extension of Time to File
An extension gives you more time to file, not more time to pay. Any tax left unpaid after April 15 accrues interest in both states, and can trigger late-payment penalties as well.9Kansas Department of Revenue. Penalty and Interest Underpayment of estimated tax has its own penalty in each state, calculated on the shortfall for each quarter it went unpaid.10Missouri Department of Revenue. Underpayment of Estimated Tax by Individuals Form MO-2210
The Kansas City Earnings Tax
Commuters in the Kansas City metro face an extra layer. Kansas City, Missouri, imposes a 1% earnings tax on anyone who lives in the city or works within its limits.11City of Kansas City. Have You Paid Your KCMO Earnings Tax E-Tax Residents pay on all earned income wherever it was earned. Nonresidents pay only on income earned inside the city.12City of Kansas City. Tax FAQs
Most employers withhold the 1% automatically. If yours does so in full, you generally do not need to file a separate return. Otherwise, file Form RD-109. Nonresidents who worked some days outside the city can use Form RD-109NR to request a refund for those days, with the day count verified by the employer.13City of Kansas City. City Tax Forms
Missouri does not credit the earnings tax on the state return, since it is local rather than state tax. Kansas is more generous. The Kansas Department of Revenue lets residents include income and earnings taxes paid to local jurisdictions in another state when computing the credit for taxes paid to that state.14Kansas Department of Revenue. Notice 15-15 Credit for Taxes Paid to Another State A Kansas resident working in Kansas City, Missouri, can combine the Missouri state tax and the 1% earnings tax on the K-40 credit worksheet. The combined credit is still capped at what Kansas would tax on that income, but because Kansas rates run higher, most of the earnings tax gets absorbed. Missouri residents working in Kansas do not get an equivalent break, though Kansas local income taxes are uncommon.
Remote and Hybrid Work
The source rule is simple when you commute to an office every day. It is harder when you work from home two days a week for an employer across the line. Income is sourced to where you physically perform the work, so days you spend working from home shift that income back to your resident state. Splitting time between states means owing tax to each in proportion to the days worked in each location.
Tracking your work location by day matters here. If your employer withholds 100% for the work state but you spend significant time working from home, you can end up over-withheld in the work state and under-withheld at home. Adjust withholding or add estimated payments before April rather than after.
The Kansas City earnings tax has the same wrinkle. Nonresidents who telework from Kansas can seek a refund on Form RD-109NR for the days worked outside the city, provided the employer verifies the count. A simple log of your work locations is one of the more effective ways to reduce the total tax you pay across all three levels.