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 an 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
The standard corporate tax rate is 6.75%
Water’s Edge Election
The water’s edge election tax rate is 7%
A corporation can apply for approval to take the water’s edge election by submitting the Water’s Edge Election (Form WE-ELECT).(15-31-322, MCA)
Alternative Gross Sales
The alternative gross sales tax rate is 0.5% on sales in Montana. (15-31-122, MCA)
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
The minimum corporate tax is $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.

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 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:

If you have no business activity during the tax year, you may file an Affidavit of Inactivity for Corporations, Partnerships and Disregarded Entities (Form INA-CT).

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.

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