Check Maryland tax deadlines for individuals and C Corporations. Confirm due dates, extension rules, and exemptions for S Corps and Partnerships.
This guide covers Maryland state tax deadlines for individuals and businesses filing 2025 returns in 2026.
Maryland Tax Deadlines at a Glance (2026)
Entity Type | Return Due | Extension Deadline |
|---|---|---|
Individuals | April 15, 2026 | October 15, 2026 |
C Corporations | April 15, 2026 | October 15, 2026 |
S Corporations | March 16, 2026 | September 15, 2026 |
Partnerships | March 16, 2026 | September 15, 2026 |
Trusts & Estates | April 15, 2026 | October 15, 2026 |
Individuals
Applies to residents, part-year residents, and nonresidents with Maryland-source income. County income tax is calculated with the state return.
Businesses
Maryland requires nonresident owner withholding for pass-through entities unless a composite or exemption applies.
Fiscal-Year Entities
Returns are due the 15th day of the 3rd or 4th month after year-end, depending on entity type.
Estimated Taxes
Quarter | Due Date |
|---|---|
Q1 | April 15, 2026 |
Q2 | June 15, 2026 |
Q3 | September 15, 2026 |
Q4 | January 15, 2027 |
Common CPA Pitfalls
Missing county tax calculations
Incorrect nonresident withholding assumptions