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E-File Mandate: Corporations are required to electronically file for all tax periods beginning after December 31, 2022 (SB 24). Corporations must use an approved corporate income tax software provider to e-file their Montana Corporate Income Tax return.

E-File Mandate does not apply if:

A corporation has gross receipts of $750,000 or less for the tax period. This is an automatic exemption from the
electronic filing requirement and Form CWR is not required.
A corporation attests, on Form CWR (Corporate E-file Waiver Request), that the corporation attempted to file
electronically and was unsuccessful or that hardship would result by filing electronically.

Any C corporation doing business in Montana has to file a Montana Corporate Income Tax Return (Form CIT) and pay a corporate income tax.

If you make a Subchapter S election at the federal level, you must also file as an S Corporation in Montana.

Tax Rates

Montana corporate tax rates are:

Standard Rate	6.75%
Water's Edge Election	7%
Water's Edge Election	A corporation can apply for approval to take the water's edge election by submitting a Water's Edge Election request on our TransAction Protal (TAP). (15-31-322, MCA)
Alternative Gross Sales	The alternative gross sales tax rate is 0.5% on sales in Montana. (15-31-122, MCA)
Alternative Gross Sales	To qualify, a corporation must: Have only sales activity in Montana, Not own or rent real estate or tangible personal property, and Have annual gross sales in Montana of $100,000 or less.
Minimum Tax	$50

See 15-31-121, MCA for more details.

Due Dates and Extensions

Your Montana Corporate Income Tax Return (Form CIT) is due:

Calendar Year	May 15
Fiscal Year	The 15th day of the 5th month following the fiscal year end. Example: If your tax year ends on September 30, your return is due on February 15.

If a due date falls on a weekend or holiday, it is due on the next business day.

Extension Deadlines

Montana grants all C corporations an automatic six-month extension to file a return. This means extensions are due:

Calendar Year	November 15
Fiscal Year	The 15th day of the 11th month following the fiscal year end. Example: If your tax year ends on September 30, your return is due on August 15.

Extension deadlines are for returns only.

Any tax liability must still be paid by the original due date or it will be subject to uniform penalties and interest.

Apportionment and Allocation of Income

Montana has adopted sections of the Multistate Tax Compact guidelines for determining what share of business income is reportable to Montana. Income will either be apportioned to Montana using an apportionment formula or directly allocated to Montana. See section 15-31-301 to 312, Montana Code Annotated, for more information on determining apportionable and non-apportionable income.

For tax periods beginning on or before June 30, 2021, Montana used an equally-weighted 3 factor apportionment formula consisting of property, payroll, and receipts.

For tax periods beginning after June 30, 2021, the apportionment formula has been changed to use a double-weighted receipts factor. This new formula consists of property, payroll, and the receipts factor counted twice.

See Montana Source Income for more details on apportionment and allocation of income.

For periods beginning after December 31, 2024 the apportionment formula will include only the receipts factor.

Federal Tax Reform—965 Income, GILTI and FDII

Montana Corporate Income Tax Treatment of International Tax Provisions under Tax Cuts and Jobs Act of 2017 (Read Online) (PDF, 515 KB)

Estimated Payments

If your business estimates owing $5,000 or more, you will need to make quarterly estimated tax payments.

Estimated payments are due on the 15th of the fourth, sixth, ninth, and twelfth months of your tax year.

Example

If your tax year ends on December 31, your estimated payments are due:

First Payment	April 15
Second Payment	June 15
Third Payment	September 15
Fourth Payment	December 15

If a due date falls on a weekend or holiday, it is due on the next business day.

If a corporation doesn't make estimated payments, it may be subject to penalties and interest. You can calculate these using the Underpayment of Estimated Tax by Corporation (Form CIT-UT).

Filing and Payment Options

You must file a Montana Corporate Income Tax Return (Form CIT) every year you do business in Montana.

You may:

File and pay using an approved corporate income tax software provider,
Make ACH Credit Payments, or
Use the Montana Corporate Income Tax Return (Form CIT).

If you have no business activity during the tax year, you may file an Affidavit of Inactivity for Corporations, Partnerships and Disregarded Entities through TAP.

See the Montana Form CIT Corporate Income Tax Booklet for more details on filing Corporate Income Tax.

Penalties and Interest

The Corporate Income Tax is subject to uniform penalties and interest.

Revenue Distribution

Corporate income tax goes into the state general fund.