Montana Estimated Tax Payments (2026)

Do you have to pay estimated taxes in Montana?

Yes. If you're self-employed in Montana and expect to owe more than $500 in Montana income tax for 2026 after withholding, you must make quarterly estimated payments to the Montana Department of Revenue. That is below the federal $1,000 threshold, so most part-time self-employed people owe them too. You're exempt if you weren't required to file a Montana return last year or your Montana tax last year was zero. Montana taxes income at graduated rates up to 5.65%.

When are Montana estimated taxes due in 2026?

Montana's 2026 quarterly payments are due April 15, June 15, September 15, and January 15, in four equal installments, on the same calendar as your federal payments.

• Q1, April 15, 2026

• Q2, June 15, 2026

• Q3, September 15, 2026

• Q4, January 15, 2027

How much should you set aside for Montana estimated taxes?

Plan to set aside 20% to 25% of your net self-employment profit to cover federal and Montana taxes combined, then confirm the exact amount with the calculator above. On $50,000 of net self-employment profit, federal self-employment tax alone is about $7,065 (15.3% on 92.35% of your earnings). On top of that you'll owe about $2,667 in federal income tax and about $1,427 in Montana income tax, for a total of about $11,159, or 22% of your profit.

How do you avoid a Montana underpayment penalty?

To avoid a Montana underpayment penalty, pay the smaller of 90% of your 2026 Montana tax or 100% of your 2025 tax, in four on-time installments. Paying the full amount late doesn't help; each installment has to be on time. You can estimate a federal underpayment penalty here.

What deductions lower your Montana estimated taxes?

Because estimated taxes are based on your net profit, every business write-off you claim lowers what you owe each quarter. Common deductions for 1099 workers, reported on Schedule C, include the home-office deduction, car mileage, phone and internet, software, and supplies. Some federal deductions carry over. Because Montana starts with the taxable income on your federal return, the federal standard deduction and three deductions you take there also lower your Montana tax: half of your self-employment tax, self-employed health insurance premiums, and self-employed 401(k) contributions. The federal Qualified Business Income (QBI) deduction is the exception: Montana adds it back, so it doesn’t lower your Montana tax.

Keeper's 1099 tax calculator estimates your bill after deductions, and our write-off guides list the deductions for your line of work.

Do self-employed people in Montana owe local or other taxes too?

Usually not. Montana has no local income tax and no general sales tax. A few resort towns, like Whitefish and West Yellowstone, add a local resort tax on lodging, restaurant meals, and some retail goods.

Note: Figures are current for the 2026 tax year and are for planning, not tax advice. Confirm the details with the Montana Department of Revenue before you file.

How to file quarterly taxes in Montana

Filing quarterly in Montana means two separate payments each period: one to the IRS for federal tax, and one to the Montana Department of Revenue for your state taxes. Here’s how to do it.

1. Confirm you need to pay. You owe estimated payments when tax isn’t withheld from enough of your income — 1099 or freelance work, investment income, or other untaxed income. Federal and Montana run separate tests: the state generally requires estimated payments if you expect to owe more than $500 in Montana tax after withholding and credits, subject to its safe-harbor rules.
2. Calculate your federal estimate. Use the Form 1040-ES worksheet (or tax software). Estimate your full-year income, add your federal income tax and self-employment tax, subtract anything already withheld from a paycheck, and split the rest across the year. The estimate at the top of this page gives you a starting number.
3. Calculate your Montana estimate separately. Work out your Montana amount on its own using Form ESW. Don’t just send part of your federal payment to the state — the Montana calculation is separate, based on your Montana income tax, credits, and any Montana withholding.
4. Pay the IRS. Pay through IRS Direct Pay (or EFTPS) and choose the estimated tax / Form 1040-ES option. Select tax year 2026 and save the confirmation number. This money counts only toward your federal taxes.
5. Pay Montana separately. Make a second payment to TransAction Portal (TAP) and select the Form ESW estimated payment for 2026. Save that confirmation too. This money counts only toward your Montana taxes.
6. Repeat on each deadline. For 2026, federal estimated payments are due April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. Montana uses those same four dates.

Steps reflect 2026 rules and are for planning, not tax advice.