2025 Maryland State Tax Deadlines

Maryland Individual Income Tax Filing deadlines and extensions for 2025 for tax professionals.

If you have clients who are residents or have been involved in significant business operations within Maryland, they might be required to file Maryland State Taxes. This page covers the most important tax deadlines and tax extensions for Maryland in 2025.

2025 Maryland State Tax Deadlines

If your clients are residents or have been involved in significant business operations within Maryland, they might be required to file Maryland State Taxes. This document outlines the most important tax deadlines and tax extensions for Maryland in 2025.

Maryland Business Tax Deadlines for 2025

C Corporation

Maryland C Corporation Tax Deadlines for 2025
You must file and pay Corporate Income Taxes in Maryland by April 15, 2026.

• File Online through the Maryland Business Express portal
• File by Mail must be postmarked by the due date
• Form 500 – Maryland Corporation Income Tax Return

Extension to File Taxes in Maryland for 2025
The Extension Deadline for Maryland corporate income tax returns is November 16, 2026.

Maryland automatically grants a six-month extension on filing corporate income tax returns. This means you do not need to file for an extension in Maryland.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Pass-Throughs

Maryland S Corporation & Partnership Tax Deadlines for 2025
You must file in Maryland by April 15, 2026.

• File Online through the Maryland Business Express portal
• File by Mail must be postmarked by the due date
• Forms:
  • 510 – S-Corporation Income Tax Return
  • 510C – Composite Pass-Through Entity Income Tax Return

Extension to File S Corporation & Partnership Taxes in Maryland for 2025
The Extension Deadline for Maryland S Corporation & Partnership income tax returns is November 15, 2026.

Maryland automatically grants a six-month extension on filing pass-through entity tax returns. This means you do not need to file for an extension in Maryland.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Maryland Individual Tax Deadlines for 2025

Estimated Tax Deadline for Maryland 2025
Estimated tax payments are due:

• April 15, 2025
• June 16, 2025
• September 15, 2025
• January 15, 2026

See Form 502D for the amount to pay with each voucher.

Individual Tax Deadline for Maryland 2025
You must file and pay Individual Income Taxes in Maryland by April 15, 2026.

• File Online through Maryland’s iFile system
• File by Mail must be postmarked by the due date
• Forms:
  • Form 502 – Resident Income Tax Return
  • Form 505 – Nonresident Income Tax Return

Extension to File Taxes in Maryland for 2025
The Extension Deadline for Maryland individual income tax returns is October 15, 2026.

Maryland automatically grants a six-month extension on filing personal income taxes. This means you do not need to file for an extension in Maryland.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Sources

• Maryland State Government Individual Filing Information
• Maryland State Government Business Tax Due Date
• Maryland Tax Forms and Instructions
• Maryland Comptroller’s Office

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The material discussed on this page is meant for general illustration and/or informational purposes only and is not to be construed as investment, tax, or legal advice. You must exercise your own independent professional judgment, recognizing that advice should not be based on unreasonable factual or legal assumptions or unreasonably rely upon representations of the client or others. Further, any advice you provide in connection with tax return preparation must comply in full with the requirements of IRS Circular 230.