2026 Delaware State Tax Deadlines

Delaware business tax deadlines for 2026

C Corporations' deadlines and requirements

C Corporations in Delaware must file and pay Corporate Income Tax by April 15, 2027, following the federal due date schedule.

Filing requirements include:

1. Complete Form 1100 (Corporate Income Tax Return)
2. File via Delaware One Stop
3. Payment must be made by April 15, 2027
4. Mail submissions must be postmarked by the due date

Extension to file taxes in Delaware for 2026

The Extension Deadline for Delaware Corporate income tax returns is October 15, 2027. Delaware automatically grants a six-month extension following the federal extension timeline without requiring separate forms. This is an extension to FILE, not an extension to PAY—payment is still due April 15, 2027.

Pass-through entities

Delaware S Corporations and Partnerships tax deadlines for 2026

S Corporations and Partnerships must file in Delaware by March 15, 2027.

Required forms include:

• Form 1100S—S Corporation Return
• Form 300—Partnership Return

Extension to file S Corporations and Partnerships taxes in Delaware for 2026

The Extension Deadline for Delaware S Corporations and Partnerships returns is September 15, 2027. Delaware automatically grants a six-month extension without requiring separate applications. This is an extension to FILE, not an extension to PAY—payment is still due March 15, 2027.

Delaware Individual tax considerations for 2026

Filing requirements and income thresholds

Delaware Individuals must file a State income tax return if their gross income exceeds specific thresholds based on filing status.

The progressive tax rates for 2026 range from:

• 0% on the first income bracket
• Up to 6.6% on higher income levels

Estimated tax deadline for Delaware 2026

Estimated tax payments are due on the following schedule for calendar year filers:

1. April 30, 2026
2. June 30, 2026
3. September 30, 2026
4. January 31, 2027

Who must make estimated payments

You must make Delaware estimated income tax payments during 2026 if you expect to owe a significant amount in Delaware income tax after subtracting withholding and credits. Electronic payments are encouraged through the Delaware online tax system.

Individual tax deadline for Delaware 2026

Individual income tax returns are due April 30, 2027 (Delaware's unique statutory deadline).

Available forms include:

• Form PIT-RES—Resident Individual Income Tax Return
• Form PIT-NON—Nonresident Individual Income Tax Return

Extension to file taxes in Delaware for 2026

The Extension Deadline is October 15, 2027, to file your Delaware Individual Income tax return. Delaware automatically grants a six-month extension without requiring separate extension forms. This is an extension to FILE, not an extension to PAY—payment is still due April 30, 2027.

What Delaware tax professionals need to know

Several key considerations make Delaware's tax landscape unique for 2026. Delaware's progressive income tax system offers moderate tax rates, and the state has a unique statutory deadline of April 30. Electronic filing requirements continue to expand, and Delaware offers various tax planning opportunities.

Electronic filing requirements

Delaware has implemented electronic filing systems for taxpayers:

• C Corporations and pass-through entities should file electronically through Delaware One Stop
• Individuals can use Delaware's online system for free electronic filing
• Business deductions can be processed more efficiently through electronic systems
• Professional preparers must use approved software vendors

Delaware's unique tax features for 2026

April 30 statutory deadline for Individual returns

Delaware has a unique April 30 statutory deadline for Individual returns (different from the federal April 15).

No local income tax

Delaware has no local income taxes.

Progressive tax rates ranging from 0% to 6.6%

Delaware provides competitive progressive tax rates for individuals.

Business-friendly incorporation laws

Delaware attracts many corporations due to its favorable business laws.

Delaware is the incorporation State

Delaware's business environment creates unique considerations:

• Many corporations are incorporated in Delaware due to its favorable business laws
• Corporate franchise tax is separate from income tax
• Expedited processing available for certain filings
• Specialized Court of Chancery for business disputes

Business incentives and credits

Delaware provides various business tax incentives:

• New Economy Jobs Program
• Strategic fund incentives
• Blue-collar jobs program
• Research and development credits

Retirement income considerations

Delaware provides certain retirement income benefits:

• Military retirement pay exemptions may apply
• Social Security benefits treatment
• Pension income considerations for residents

Professional tax guidance

For complex Delaware tax situations, consulting with qualified tax professionals through an accounting firm directory can help ensure compliance and identify available tax-saving opportunities.

Sources

• Delaware Department of Revenue
• Delaware One Stop Portal

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