Montana Tax Year 2026

Montana 1099-INT Filing Requirements, Tax Year 2026

What Montana requires from businesses filing 1099-INT (Interest income) for tax year 2026: deadline, accepted format, CF/SF treatment, registration, and penalties, backed by primary-source citations.

Tax Year 2026 Direct state filing required Last verified April 26, 2026
Rules below assume no Montana tax was withheld on these 1099-INT filings. If you withheld Montana income tax, separate or different state filing requirements apply; see conditional rules.
Filing method Direct state filing Submit 1099-INT directly to Montana.
Deadline April 1 See deadlines section for holiday rollover. See deadlines
Format accepted Fire Filed via TransAction Portal (TAP) — single upload or bulk FLE — using IRS Publication 1220 layout. Paper alternative: mail with Federal Form 1096. See format
Late-filing penalty **Late File Penalty (general):** $50 minimum, or 5% of outstanding tax per month, up to 25% of tax due (Montana DOR Interest and Penalties). See penalties

Filing requirements

Montana requires direct filing of 1099-INT with the state for tax year 2026. Federal filing through the IRS Combined Federal/State Filing (CF/SF) Program does not, on its own, satisfy the Montana requirement for 1099-INT; a separate state submission is required.

Montana requires 1099-INT filing with the Department of Revenue. With no Montana withholding, the deadline mirrors federal: February 28 on paper or April 1 if e-filed via the TransAction Portal. Submit with Federal Form 1096 (paper) or upload directly to TAP. If Montana income tax was withheld on the interest payment, the 1099-INT is bundled with Form MW-3 by January 31 instead.

Conditional rules

The summary above applies when no Montana tax was withheld. The conditions below describe what changes when withholding is present, plus other scenario-specific rules:

ConditionExplanation
Deadline shifts to January 31 with MW-3 if Montana tax was withheld

When Montana state income tax was withheld on a 1099-INT payment, the form must be submitted with Form MW-3 (the annual withholding reconciliation) by January 31, not February 28 / April 1.

Deadlines and extensions

Filing deadline
April 1
Holiday/weekend rollover. If the deadline falls on a weekend or a federal holiday, the next business day generally applies. Check with Montana for the exact observed calendar before filing.

Accepted format

Fire

Filed via TransAction Portal (TAP) — single upload or bulk FLE — using IRS Publication 1220 layout. Paper alternative: mail with Federal Form 1096.

Filing portal: TransAction Portal (TAP) — https://tap.dor.mt.gov

Transmittal form required: MW-3 (Montana Annual W-2 1099 Withholding Tax Reconciliation)

Registration

Registration required: Yes

Filing through TAP requires a GenTax withholding account with TAP access. TAP File Process (FLE) accounts handle bulk uploads up to 51 MB; larger volumes use the Web Service API. Filers may also mail paper 1099s with Federal Form 1096 to Montana DOR (PO Box 5835, Helena MT 59604-5835); a withholding account is NOT required if all 1099s being submitted have no Montana withholding.

Late-filing penalties

Montana penalty overview

Late File Penalty (general): $50 minimum, or 5% of outstanding tax per month, up to 25% of tax due (Montana DOR Interest and Penalties).

W-2 late filing penalty: $50 per W-2, with a $250 minimum (effective for forms due in 2024 per SB 303 / 68th Legislature).

Mineral Royalty 1099 late filing penalty: $150 per 1099, with a $1,000 minimum (effective for forms due in 2024).

Truncated TIN forms: Montana does not accept Forms 1099 with truncated SSN/FEIN; non-resubmission by the due date may trigger late filing penalties.

Frequently asked questions

Does Montana require filing of 1099-INT for tax year 2026?

Yes. Montana requires direct filing of 1099-INT with the state for tax year 2026. Federal filing alone does not satisfy this requirement.

Does Montana participate in the CF/SF program?

Listed only. Montana appears on the IRS Combined Federal/State Filing Program list, but the state's tax agency does not accept CF/SF as a substitute - 1099 filings must go through the state's direct filing channel when required.

What is the Montana 1099-INT filing deadline for tax year 2026?

The filing deadline is April 1. If the date falls on a weekend or federal holiday, the next business day generally applies.

What format does Montana accept for 1099-INT?

Montana accepts Fire format for direct 1099-INT filings. Filed via TransAction Portal (TAP) — single upload or bulk FLE — using IRS Publication 1220 layout. Paper alternative: mail with Federal Form 1096.

Do I need to file 1099-INT with Montana if I also filed federally?

Yes. Even if you file 1099-INT federally with the IRS, Montana requires a separate direct state filing for tax year 2026.

What happens if I miss the Montana 1099-INT deadline?

**Late File Penalty (general):** $50 minimum, or 5% of outstanding tax per month, up to 25% of tax due (Montana DOR Interest and Penalties). See the full penalty details below for the complete schedule.

How do I register to file with Montana?

Filing through TAP requires a GenTax withholding account with TAP access. See the registration section above for the full requirements.

Source citations

Verified from 6 primary sources
“seems to conflict with other sites. Sovos says only if payment is > 600. file just to be safe? has dates listed for each individual form type in docs”
Apr 23, 2026 https://revenue.mt.gov/taxes/withholding-tax/1099-without-withholding-due-dates
“(1) Each information agent shall make a return to the department of complete information concerning the following distributions made for any individual during the tax year upon which withholding tax has not been deducted: (a) sums in excess of $10 distributed as dividends, interest as defined in section 6049 of the Internal Revenue Code, 26 U.S.C. 6049, royalties, and payments made under a retirement plan”
Apr 25, 2026 https://mca.legmt.gov/bills/mca/title_0150/chapter_0300/part_0260/section_0160/0150-0300-0260-0160.html
“You can submit Forms 1099 using the File Upload in our TransAction Portal (TAP) or mail your Forms 1099 to: Montana Department of Revenue PO Box 5835 Helena, MT 59604-5835”
Apr 25, 2026 https://revenuefiles.mt.gov/taxes/withholding-tax/1099-without-withholding-due-dates
“Due Dates for Forms 1099 Without Withholding … 1099-INT Interest Income February 28 April 1”
Apr 25, 2026 https://revenuefiles.mt.gov/taxes/withholding-tax/1099-without-withholding-due-dates
“1099s How do I use TAP to file a 1099? Manual entry in TAP Withholding account Single upload in TAP Withholding account … Please ensure that the form you are using adheres to the specifications set forth in IRS Publication 1220”
Apr 25, 2026 https://revenuefiles.mt.gov/online-services/transaction-portal/electronic-filing-of-mw-3s-1099s-and-w2s-instructions
Conditional: Deadline shifts to January 31 with MW-3 if Montana tax was withheld
“Wage Withholding Reports and Payment Due Dates … Montana Annual W-2 1099 Withholding Tax Reconciliation (Form MW-3) January 31 … Forms 1099 with Withholding January 31”
Apr 25, 2026 https://revenue.mt.gov/taxes/withholding-tax/wage-withholding-returns-and-payments

Additional notes

Montana requires payers ("information agents") to file 1099s with the Montana Department of Revenue under MCA 15-30-2616. The TransAction Portal (TAP) at https://tap.dor.mt.gov accepts 1099 uploads in IRS Publication 1220 format; paper filers attach Federal Form 1096. Forms 1099 with Montana withholding must be submitted with Form MW-3 by January 31. Forms 1099 without Montana withholding follow federal due dates: 1099-NEC by January 31; 1099-MISC (Box 2 royalty) by February 28 (both paper and e-file); other 1099s (INT, DIV, K, R, C, etc.) by February 28 on paper or April 1 if e-filed. Montana does not mandate electronic filing for 1099s.

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