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Delaware 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 Delaware, then they might be required to file Delaware State Taxes. This page covers the most important tax deadlines and tax extensions for Delaware in 2025.
If your clients are residents or have been involved in significant business operations within Delaware, then they might be required to file Delaware State Taxes. This page covers the most important tax deadlines and tax extensions for Delaware in 2025.
Delaware C Corporation Tax Deadlines for 2025
You must file and pay Corporate Income Taxes in Delaware by April 15, 2026.
Extension to File Taxes in Delaware for 2025
The Extension Deadline for Delaware corporate income tax returns is October 15, 2026.
Delaware grants a six-month extension for filing corporate income tax returns automatically. This means you do not need to file for an extension in Delaware.
This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.
Delaware S Corporation & Partnership Tax Deadlines for 2025
You must file in Delaware by March 15, 2026.
Extension to File S Corporation & Partnership Taxes in Delaware for 2025
The Extension Deadline for Delaware S Corporation and Partnership tax returns is September 15, 2026.
Delaware automatically grants a six-month extension for filing pass-through entity tax returns. This means you do not need to file for an extension in Delaware.
This is an extension to FILE, not an extension to PAY – payment is still due March 15, 2026.
Estimated Tax Deadline for Delaware 2025
Estimated tax payments are due:
Individual Tax Deadline for Delaware 2025
You must file and pay Individual Income Taxes in Delaware by April 30, 2026.
Extension to File Taxes in Delaware for 2025
The Extension Deadline for Delaware individual income tax returns is October 15, 2026.
Delaware automatically grants a six-month extension for filing personal income taxes. This means you do not need to file for an extension in Delaware.
This is an extension to FILE, not an extension to PAY – payment is still due April 30, 2026.
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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.
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