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Montana Business State Tax Extension I C Corporations Filing Guide

Form CT | Montana Corporate Income Tax Payment Voucher  ·  C Corporations  ·  Business Filing Guide

Overview

Montana C Corporations are subject to state corporate income tax requirements, administered by the Montana Department of Revenue. Montana automatically grants an extension to file with no application or form submission required.

Original Filing Deadline

The original due date for the Montana C Corporations return is April 15, 2026. File or remit full payment by this date to remain in good standing.

Extension Granted Automatically

Montana automatically grants a filing extension for C Corporations. The extended filing deadline is November 15, 2026. No application or form submission is required to receive this extension.

Payment Is Still Due by Original Deadline

The extension applies to filing only—it is not an extension to pay taxes owed. Any outstanding tax liability must be paid by the original due date of April 15, 2026 to avoid penalties and interest. Use the Montana | Online Tax Extension Payment to pay electronically. For mail-in payments, use Form CT | Montana Corporate Income Tax Payment Voucher and send to: Montana Department of Revenue PO Box 8021 Helena, MT 59604-8021

Late Filing and Payment Penalties

• Failure to File: Lesser of $50 or tax due.
• Failure to Pay: 1.2% a month or fraction of a month on the unpaid tax, up to 12%.

Best Practices

• Estimate and pay your Montana business tax by April 15, 2026 to avoid interest and penalties.
• No extension form is required—Montana grants the extension automatically.
• Use the state online payment portal for fast, convenient electronic payment.
• Set a reminder to file your completed Montana C Corporations return by November 15, 2026.

Final Thoughts

• Montana’s automatic extension simplifies the process—no paperwork required. Pay any balance due by April 15, 2026 and file your return by November 15, 2026.
• Quick Reference Table
• State Abbreviation
• MT
• State Name
• Montana
• Business Entity Type
• C Corporations
• Extension Status
• Approved Automatically
• Return Due Date
• April 15, 2026
• Extended Due Date
• November 15, 2026
• Other Information
• Montana grants you an automatic 6-month extension to file your business tax return. The extension is NOT an extension to pay any taxes you may have due. Tax payments are due by the original return due date.
• Online Payment
• Montana | Online Tax Extension Payment
• Payment Voucher Form
• Form CT | Montana Corporate Income Tax Payment Voucher
• State Payment Agency
• Montana Department of Revenue
• Mailing Address with Payment
• Montana Department of Revenue PO Box 8021 Helena, MT 59604-8021
• Failure to File Penalties
• Lesser of $50 or tax due.
• Failure to Pay Penalties
• 1.2% a month or fraction of a month on the unpaid tax, up to 12%.

Working with a Tax Professional

Business tax returns are complex—a licensed CPA or Enrolled Agent can maximize deductions, ensure accurate calculations, and handle filing on your behalf. Here's how working with a TaxPro typically goes:

1. 1Get matched with a verified U.S.-based CPA or Enrolled Agent
2. 2Upload your business documents via secure drag-and-drop
3. 3Review and approve your return with upfront, transparent fees
4. 4Your TaxPro files your Montana return by November 15, 2026

Quick Reference Table

State Abbreviation	MT
State Name	Montana
Business Entity Type	C Corporations
Extension Status	Approved Automatically
Return Due Date	April 15, 2026
Extended Due Date	November 15, 2026
Other Information	Montana grants you an automatic 6-month extension to file your business tax return. The extension is NOT an extension to pay any taxes you may have due. Tax payments are due by the original return due date.
Online Payment	Montana | Online Tax Extension Payment
Payment Voucher Form	Form CT | Montana Corporate Income Tax Payment Voucher
State Payment Agency	Montana Department of Revenue
Mailing Address with Payment	Montana Department of Revenue PO Box 8021 Helena, MT 59604-8021
Failure to File Penalties	Lesser of $50 or tax due.
Failure to Pay Penalties	1.2% a month or fraction of a month on the unpaid tax, up to 12%.