Missouri started accepting 2025 state income tax returns on January 26, 2026, and the filing deadline is April 15, 2026.1Missouri Department of Revenue. Department of Revenue Now Accepting 2025 Tax Returns If you want to know when you can file your Missouri state taxes in any given year, the practical answer is late January, as soon as the Department of Revenue opens electronic filing alongside the IRS. You can submit a return any time between that opening date and the April deadline, and an extension pushes the filing cutoff to October 15 if you need it.2Missouri Department of Revenue. Form MO-60 – 2025 Application for Extension of Time to File
Why You Can’t File the Day the Window Opens
Even once Missouri’s system is live, you need your federal return done first. Form MO-1040 pulls key figures straight from your federal Form 1040, most importantly your federal adjusted gross income. You cannot accurately complete the state form without finishing the federal one, which is why the Missouri Department of Revenue times its opening to the IRS filing season in late January.
In practice, that means gathering your paperwork before the window opens so you can file as soon as you have what you need. Collect your W-2s from employers and any 1099 forms for freelance income, investment earnings, or retirement distributions. If you plan to claim Missouri-specific credits, such as the property tax credit, pull that documentation together too. Most tax software walks you through the federal return first and then populates the Missouri return from it in the same session.
Filing early has one concrete benefit beyond crossing it off your list: refunds. Electronic returns appear in the DOR’s tracking system within about five business days, while paper returns take three to four weeks just to show up as received.3Missouri Department of Revenue. Obtaining the Status of Your Tax Return The earlier you file electronically, the sooner any refund lands.
The April 15 Deadline
The standard filing deadline is April 15. When April 15 falls on a weekend or legal holiday, the deadline shifts to the next business day. This has shifted before. In one recent year the deadline moved to April 17 to match a federal change tied to the District of Columbia’s observation of Emancipation Day.4Department of Revenue. As April 17 Deadline Approaches, Department of Revenue Offers Tips for Tax Return Filers For the 2025 tax year, April 15, 2026, is a Wednesday, so the standard date holds.
You can file electronically through approved tax software, which gives you an immediate confirmation of receipt and faster refund processing. Missouri also participates in the Free File Alliance, which offers free online filing for qualified taxpayers through partnering software providers.5Missouri Department of Revenue. Individual Income Tax Electronic Filing Keep your e-file confirmation code, or a certified mail receipt if you’re sending paper, as proof you met the deadline.
If You Need More Time: Extensions to October 15
If you can’t finish by April 15, there are two routes to a Missouri extension.
The simpler route works if you’re already filing for a federal extension. File IRS Form 4868, and Missouri automatically grants you a matching state extension until October 15, 2026. You don’t need to file any additional state paperwork, as long as you don’t expect to owe money.2Missouri Department of Revenue. Form MO-60 – 2025 Application for Extension of Time to File Attach a copy of your federal extension when you eventually file your Missouri return.6Missouri Department of Revenue. FAQs – Individual Income Tax
The second route applies if you want a Missouri extension without a federal one, or if you expect to owe tax. In that case, submit Form MO-60 with your payment by the original April deadline.2Missouri Department of Revenue. Form MO-60 – 2025 Application for Extension of Time to File
One point trips people up every year. An extension gives you more time to file, not more time to pay. Any tax you expect to owe must still be paid by April 15. If you underpay, interest and penalties begin accruing on the balance immediately.
What Happens If You Miss the Deadline
Missouri assesses separate penalties depending on whether you’re late filing, late paying, or both. The filing penalty is the heavier of the two.
- Late filing penalty: 5% of the unpaid tax per month, capped at 25% of the unpaid balance. This applies when you miss the April deadline, or your extended October deadline, without filing a return.6Missouri Department of Revenue. FAQs – Individual Income Tax
- Late payment penalty: a one-time 5% addition on the unpaid balance when you file by the deadline but don’t pay what you owe by April 15.6Missouri Department of Revenue. FAQs – Individual Income Tax
- Interest: the DOR charges 7% annual interest on unpaid tax balances for the 2026 calendar year, accruing from the original due date until the balance is paid.7Missouri Department of Revenue. Statutory Interest Rates
The practical takeaway: if you can’t do both on time, filing on time matters more than paying on time. A return filed by the deadline with an unpaid balance triggers only the 5% payment penalty. A return filed late with an unpaid balance stacks the monthly filing penalty on top. File the return and pay whatever you can by April 15, even if it isn’t the full amount.
When Your Refund Will Arrive
After you file electronically, your return shows up in the DOR’s refund tracking system within about five business days. Paper returns take three to four weeks just to appear in the system, before any processing time on top of that.3Missouri Department of Revenue. Obtaining the Status of Your Tax Return If a refund is your main reason for filing early, electronic filing is the only version of “early” that pays off.
Who Doesn’t Need to File at All
Before you worry about dates, confirm you actually have to file. If you’re not required to file a federal return, you don’t need to file a Missouri return either.6Missouri Department of Revenue. FAQs – Individual Income Tax
If you are required to file federally, Missouri residents can skip the state return only if their Missouri adjusted gross income is below $1,200 or falls under the combined total of their standard deduction plus personal exemption.6Missouri Department of Revenue. FAQs – Individual Income Tax For the 2025 tax year, the standard deduction is $15,750 for single filers and $31,500 for married couples filing jointly.8Missouri Department of Revenue. 2025 Individual Income Tax Year Changes Most working Missourians with income above those levels will need to file.
Non-residents who earned $600 or more of Missouri-source income must file a state return. Part-year residents also need to file, and should include either Form MO-CR, to claim a credit for taxes paid to another state, or Form MO-NRI, to pay tax only on income earned while living in Missouri, along with Form MO-1040.9Missouri Department of Revenue. Nonresidents and Residents with Other State Income
One situation catches people off guard. Even if you fall below these thresholds and don’t technically owe a return, you still need to file one to get back any Missouri tax that was withheld from your paychecks.6Missouri Department of Revenue. FAQs – Individual Income Tax In that case, the opening date of filing season is simply the first day you can start the refund clock.