2027 Maryland Tax Deadlines

Last updated: August 5, 2026

Key Maryland tax dates at a glance

• April 15, 2027: First Individual estimated payment.
• June 15, 2027: Second Individual estimated payment.
• September 15, 2027: Third Individual estimated payment.
• January 18, 2028: Fourth Individual estimated payment.
• April 18, 2028: Calendar-year C Corporation, S Corporation, Partnership, and Individual returns and payments.
• October 16, 2028: Extended Partnership and Individual returns, file only.
• November 15, 2028: Extended C Corporation and S Corporation returns, file only.

When are Maryland taxes due in 2027?

Maryland 2027 calendar-year C Corporation, S Corporation, Partnership, and Individual returns are generally due April 18, 2028. Partnership extensions run to October 16, 2028, while C Corporation and S Corporation extensions can run to November 15, 2028.

When is the Maryland C Corporation return due?

Maryland C Corporations should plan around April 18, 2028, for the calendar-year corporate-facing return, tax, or business-level filing noted in this page.

• Form 500: Maryland Corporation Income Tax Return.
• Form 500E: Application for Extension of Time to File Corporation Income Tax Return.
• File and pay through Maryland Tax Connect.

What are Maryland C Corporation extension rules?

The extended filing deadline for the main calendar-year Maryland corporate-facing return is November 15, 2028. The extension is to file only, and tax or required payments remain due by April 18, 2028.

When are Maryland S Corporation and Partnership returns due?

Maryland S Corporations should plan around April 18, 2028, and Partnerships should plan around April 18, 2028.

Which Maryland pass-through forms are required?

Use the applicable Maryland pass-through return and related payment or owner-reporting forms for the entity type and election facts.

• Form 510: S Corporation and Partnership pass-through entity return.
• Form 511: Maryland Pass-Through Entity Election Income Tax Return.

What are Maryland pass-through extension rules?

The extended filing deadline for calendar-year Maryland S Corporation and Partnership returns is October 16, 2028, for Partnerships and November 15, 2028, for S Corporations. The extension is to file only, so tax, withholding, composite, or entity-level payments should be handled by the original deadline.

When is the Maryland Individual income tax return due?

Calendar-year Maryland Individual income tax returns and payments are due April 18, 2028.

• Form 502: Resident Individual income tax return.
• Form 505: Nonresident Individual income tax return.
• Form 502D: Individual estimated tax declaration.

What Maryland Individual rate and residency issues should be checked?

Tax year 2027 Individual instructions should be checked for final rate tables, standard deductions or exemptions, residency rules, retirement-income treatment, credits, estimated-payment thresholds, and any filing-year changes specific to Maryland.

When are Maryland estimated payments due?

Maryland estimated-payment planning should include both state tax and applicable local county income tax.

• April 15, 2027: First estimated payment.
• June 15, 2027: Second estimated payment.
• September 15, 2027: Third estimated payment.
• January 18, 2028: Fourth estimated payment.

Who must make Maryland estimated payments?

Taxpayers should use the final 2027 Maryland instructions to confirm estimated-payment thresholds, safe-harbor rules, credits, withholding, pass-through owner treatment, and electronic-payment requirements.

What are Maryland extension deadlines?

Maryland extension deadlines are October 16, 2028, for Partnerships and November 15, 2028, for S Corporations for pass-through filings, November 15, 2028, for corporate-facing filings, and October 16, 2028, for Individual returns. Extensions add filing time only; payment deadlines remain tied to the original return due dates.

What Maryland-specific rules should tax professionals watch for 2027?

Beyond the core return deadlines, Maryland tax professionals should track state-specific rate, credit, local-tax, industry, and filing-method rules before the 2027 season locks.

• Maryland's state Individual rates range from 2% to 6.5%, plus county income tax generally ranging from 2.25% to 3.30%.
• Individuals generally make estimated payments when expected Maryland tax after withholding and credits is at least $500, including applicable local income tax.
• Maryland residents calculate county income tax through a local income tax system covering 23 counties plus Baltimore City, and year-end reconciliation may be needed when withholding does not match the residence-based rate.
• Eligible S Corporations and Partnerships may elect Maryland's entity-level tax; coordinate Form 511, member credits, estimates, and extension treatment.
• Maryland generally gives Partnerships six months and S Corporations seven months, so October and November extended deadlines should stay separate.
• Maryland provides subtraction modifications for qualifying retirement income, including a military retirement pay exclusion, and Social Security benefits are generally exempt from Maryland state income tax.
• Eligible taxpayers may claim Maryland's Earned Income Tax Credit, with refundable and nonrefundable treatment checked against tax-year instructions.
• Business incentives to review include Enterprise Zone credits, job-creation tax credits, research and development tax credits, brownfields-related credits, and small-business relief credits.
• Biotechnology, life-sciences, and federal contracting sectors can create research incentives, investment credits, and specialized compliance considerations.
• Chesapeake Bay and environmental programs may involve Bay-restoration fees, environmental tax credits, green-building incentives, and stormwater-management fees.

Instead AI helps tax teams treat Maryland due dates as operational work, not a static checklist.

Tax-professional context: Maryland's tax landscape is distinctive for 2027 because a progressive state income tax combines with mandatory county (local) income tax, producing some of the highest combined effective rates on the East Coast. Electronic filing requirements continue to expand, and despite the high-tax environment Maryland offers meaningful subtraction modifications and business credits that reward proactive planning. Tax professionals should confirm final 2027 rate tables, local rates, credit parameters, and estimated-payment thresholds against the current-year Maryland instructions before the season locks.

Electronic filing requirements:

• C Corporations and pass-through entities should file and pay electronically through Maryland Tax Connect.
• Individuals can e-file through Maryland's online system, including free options.
• Professional preparers must use approved software vendors.
• Business deductions and payments process more efficiently through electronic systems.

Business Tax Credits:

• Enterprise Zone credits
• Job creation tax credits
• Research and development tax credits
• Brownfields cleanup credits
• Small business relief tax credits

Local income tax:

• 23 counties plus Baltimore City each set local rates, generally 2.25% to 3.30%.
• Withholding is based on work location, but liability is based on county of residence.
• Year-end reconciliation may be required for residents who work in a different county.
• Combined state and local effective rates can exceed 9% for higher earners.

Retirement income considerations:

• Military retirement pay exemptions may apply.
• Social Security benefits are generally exempt from Maryland state income tax.
• Pension income subtraction modifications for qualifying taxpayers.
• Senior citizen tax benefits and credits.

Earned Income Tax Credit: Eligible taxpayers may claim Maryland's EITC, with refundable and nonrefundable treatment confirmed against the 2027 instructions.

Biotechnology and federal contractor focus:

• Special provisions for research and development activities
• Federal contracting compliance considerations
• Biotechnology tax incentives and life-sciences investment credits

Chesapeake Bay and environmental considerations:

• Bay-restoration fees on certain businesses
• Environmental tax credits
• Green-building incentives
• Stormwater-management fees

High-tax-environment planning:

• Multi-state tax planning for high-income earners
• Retirement income planning to maximize subtraction modifications
• Business structure planning
• Timing strategies for income and deductions

Maryland's retirement subtractions and separate business filing rules reward specialist review from the accounting firm directory.

What sources support these Maryland dates?

• Maryland business tax forms and instructions.
• Maryland business income tax forms.
• Comptroller of Maryland.

Coordinate Maryland state and county deadlines

Instead's AI-driven tax platform helps Maryland teams coordinate return work, payment review, extensions, and filing follow-through before deadlines move from planning to execution.

For Maryland practices, workflows, planning, and integrations help connect research, planning, and operational handoffs without duplicating deadline data. Built for tax professionals who want source-backed state deadline control across clients, entities, and reviewer workflows.