View the complete 2026 Delaware tax deadline schedule. Updated due dates for Individuals (Apr 30), C-Corps, and S-Corps (Mar 16), plus estimated tax rules.
Delaware imposes both individual and corporate income taxes with specific filing schedules that differ from federal dates.
For individuals, the Delaware Division of Revenue sets the filing deadline at April 30. Taxpayers may file Form PIT‑EXT to receive an extension until October 15; however, this extension applies only to the filing of the return—any tax due must still be paid by April 30 to avoid interest. Estimated tax payments for individuals are due in four installments: April 30, June 15, September 15, and January 15.
For corporations (C Corps), returns (Form CIT) are due on or before the 15th day of the fourth month following the close of the taxable year. A federal extension automatically extends the state filing date by six months. Unlike the federal schedule, Delaware corporate estimated tax is paid in installments of 50%, 20%, 20%, and 10% on the 15th day of the 4th, 6th, 9th, and 12th months.
2026 Filing & Payment Schedule
Filing Type | Regular Due Date | Extension Deadline | Quarterly Estimated Payments |
Individuals | April 30 | Oct 15 (Form PIT‑EXT) (Payment due Apr 30) | Apr 30, June 15, Sept 15, Jan 15 |
C Corporations | April 15 | Oct 15 (w/ Federal Ext) (Payment due Apr 15) | 50% (Apr 15), 20% (June 15), 20% (Sept 15), 10% (Dec 15) |
S Corps & Partnerships | March 16* | Sept 15 (Payment due Mar 16) | Follow individual estimated payment schedule |
Fiduciary / Estates | April 30 | Oct 15 (Form PIT‑EXT) (Payment due Apr 30) | Not applicable |
*Note: The standard March 15 deadline falls on a Sunday in 2026, moving the due date to the next business day.
Detailed Deadlines by Entity
Individual Return Deadlines
Due Date: Delaware individual income tax returns (Form PIT‑R) are due April 30 for calendar‑year taxpayers. Fiscal year filers must file by the last day of the fourth month following the close of their tax year.
Extension: Form PIT‑EXT extends the filing date to October 15 but does not extend the time to pay. Interest accrues on any unpaid tax remaining after April 30.
Estimated Tax: Taxpayers expecting to owe at least $400 in state tax must pay estimated tax in four installments: April 30, June 15, September 15, and January 15.
Business Return Deadlines
Corporations: Delaware corporate income tax returns (Form CIT) are due on the 15th day of the fourth month following the close of the tax year (April 15 for calendar year filers). A federal extension extends the state filing deadline by six months, but the full tax balance is due by the original deadline.
Tentative Tax: Estimated tax is paid in weighted installments of 50%, 20%, 20%, and 10% on the 15th day of the 4th, 6th, 9th, and 12th months.
S Corporations and Partnerships: These entities file by the 15th day of the third month. Because March 15 falls on a Sunday in 2026, the deadline is March 16. An extension to September 15 is available. Income generally flows through to the owners' individual returns.
Fiduciary Returns: Trust and estate fiduciary returns are due April 30, with an available extension to October 15. Estimated payments are generally not required.