Missouri calendar and forms

Missouri keeps its calendar locked to the federal one. Form MO-1040 is due April 15, 2027, the same day as the federal return; the four estimated payments fall on the federal dates; and the extension runs to October 15, 2027. The one Missouri habit worth learning is how the extension is granted. If you have a federal extension and expect no Missouri balance, you have a Missouri extension too, with no form. If you expect to owe, you file Form MO-60 with the payment by April 15, and the extension buys time to file but not to pay: tax unpaid after April 15 draws a 5% addition plus interest no matter what. The form side is one return, Form MO-1040, and a handful of attachments that apply only when they apply, led by Form MO-A, where every Missouri difference from the federal return lives.

Most Missouri filers touch two or three pages: the MO-1040, the MO-A, and either MO-WFTC for the Working Family Tax Credit or MO-PTS for the senior Property Tax Credit. The rest of the list below is for people who moved, who work across the state line, who owe estimated tax, or who live or work in Kansas City or the City of St. Louis and owe a second, local return.

The 2027 filing season, dated

How the extension really works

Missouri has two extension paths and the choice depends on one question: will you owe? If you filed federal Form 4868 and expect no Missouri balance due, the Missouri extension is automatic. You check the box on the MO-1040 when you file and attach a copy of the federal extension. Nothing is sent to Jefferson City in April.

If you expect to owe, file Form MO-60, Application for Extension of Time to File, with the expected payment by April 15. MO-60 can also be used by someone with no federal extension. Either way, the extension covers the return, not the money. Tax not paid by April 15 draws an addition to tax of 5% plus interest from April 15 until paid, and the addition applies even if the return is filed within the extended period. The arithmetic is the same as the federal Form 4868: pay what you expect to owe in April and finish the return in October.

Estimated payments

Missouri requires estimated payments when the Missouri tax expected for the year, after withholding and credits, is $100 or more. Payments go on Form MO-1040ES vouchers or through MyTax Missouri on the four federal dates. There is no addition to tax if each installment is paid on time and the payments to date equal either the tax shown on last year’s 12-month Missouri return or 90% of this year’s tax (66⅔% for farmers). Missouri has no 110% tier for higher incomes. The addition for a late or short installment is figured on Form MO-2210, and interest runs at 7% for 2026 and for 2027.

The Missouri filers most often caught are retirees. Social Security is exempt at 62 and a government pension largely so, but IRA and 401(k) withdrawals are taxed at 4.7% above a $6,000 exemption that disappears at $25,000 single or $32,000 married filing combined of Missouri AGI, and most custodians withhold no Missouri tax unless asked. A single retiree drawing $40,000 a year from an IRA owes Missouri roughly $850 and should either request Missouri withholding on the distributions or send four vouchers.

The forms, in the order a filer meets them

The two city returns

Kansas City and the City of St. Louis each levy a 1% earnings tax, and each has its own return outside the Department of Revenue. A resident of either city owes 1% on all earnings wherever earned; a nonresident owes 1% on wages for work physically performed inside the city. Employers withhold it and report it in W-2 box 19, and an employee whose withholding covers the tax generally has nothing more to file. Kansas City residents and self-employed people file Form RD-109; a nonresident who worked some days outside the city claims a prorated refund on Form RD-109NR, due by the federal filing deadline. St. Louis uses Form E-1, and nonresidents claim remote-work days on Form E-1R. Earnings tax paid is deductible on the Missouri itemized schedule, MO-A Part 2, for filers who itemize. Both taxes were renewed by voters on April 7, 2026 for five more years.

Filing, paying and checking a refund

Missouri has no e-file mandate for individuals and no Department-built free return for the general public. Free filing comes through the Free File Alliance: the Department lists approved software providers that file the federal and Missouri returns together at no charge for taxpayers who meet each vendor’s own limits, which vary by vendor and year. IRS Direct File never included Missouri. Most Missouri returns are e-filed with the federal return through commercial software or a preparer, and paper is accepted.

MyTax Missouri, at mytax.mo.gov, is the Department’s portal for payments, estimated payments, the Property Tax Credit claim and account access; a bank debit there costs nothing. Refund status is at the Department’s Return Inquiry System, dor.mo.gov/taxation/return-status, which needs the Social Security number, the filing status and the exact refund or balance due. An e-filed return appears in the system within about five business days; a paper return takes three to four weeks to appear, and longer to pay. The Department may hold a refund and send a letter asking you to confirm your identity before it is released; the letter comes by mail, now by first-class mail under a 2026 law, never by text.