Delaware tax deadlines in 2026: filing dates and estimated payments
Deadlines that fall in calendar 2026: the 2025 return and the 2026 estimated payments. Different year? See Delaware 2025 →
Delaware deadlines in 2026
| 2025 individual return due | April 30, 2026 |
|---|---|
| Extended filing deadline | October 15, 2026 |
| Payment due | April 30, 2026, extension or not |
| Final 2025 estimated payment | January 15, 2026 |
| 2026 estimated payments | April 30, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Individual returns are due April 30 (not April 15). Extension to file to October 15; payment still due April 30. First estimated installment falls on April 30.
Delaware estimated tax payments in 2026
Every resident and non-resident individual whose tax due in excess of withholding can reasonably be expected to exceed $800.
| Q1 (2026 tax year) | April 30, 2026 |
|---|---|
| Q2 (2026 tax year) | June 15, 2026 |
| Q3 (2026 tax year) | September 15, 2026 |
| Q4 (2026 tax year) | January 15, 2027 |
| Voucher | Form PIT-EST (formerly Form 200-ES) |
| Underpayment safe harbor | No penalty if each installment is timely and totals at least 90% (66 2/3% for farmers and fishermen) of the current-year tax, or 100% of the prior-year tax (110% if prior-year federal AGI exceeded $150,000, $75,000 MFS); no estimate required if there was no tax liability for the preceding 12-month year. |
| Pay online | tax.delaware.gov |
Delaware's first installment is April 30 (not April 15); the remaining installments are June 15, September 15 and January 15. Underpayment penalty is 1 1/2% per month. Farmers/fishermen (2/3 of gross income) may file the declaration and pay by January 15 and file the return by April 30, or file and pay in full by March 1. Credit-card payments capped at $10,000 via the portal. Fiscal-year filers: 30th day of 4th month, 15th day of 6th and 9th months, 15th day of 1st month of next year.
Source: revenuefiles.delaware.gov, read September 3, 2026. “Your Estimated Tax may be paid in full with the first Declaration filed for the tax year, or in equal installments on or before April 30, June 15, September 15, and January 15 of the following year.”
All 51 jurisdictions in one table: state estimated tax payment dates for 2026.
Delaware extensions
Every state's rule in one table: which states accept the federal extension in 2026.
| Does Delaware accept the federal extension? | No. File the state's own extension request. |
|---|---|
| State extension form | Form PIT-EXT |
| Original due date | April 30, 2026 |
| Extended due date | October 15, 2026 |
| Payment | Still due April 30, 2026. The extension is to file, not to pay. There is no extension of time for payment; interest accrues at 1/2% per month on unpaid tax from the original due date. |
| How to get it | File Form PIT-EXT (online at tax.delaware.gov or by mail) with any balance due by April 30, 2026. |
The 2025 instructions tie the extension to filing PIT-EXT and do not offer the federal Form 4868 as a substitute; the PIT-EXT form itself states the automatic extension runs to October 15, 2026.
Source: revenuefiles.delaware.gov, read September 3, 2026. “An extension of time to file your tax return is granted when the Application for Automatic Extension (Form PIT-EXT) is filed prior to the due date of your return.”
Federal deadlines in 2026
| 2025 Form 1040 | April 15, 2026 · extension October 15, 2026 |
|---|---|
| 2025 S-corp (1120-S) & partnership (1065) | March 16, 2026 |
| 2025 C-corp (Form 1120) | April 15, 2026 |
| 2026 federal estimated payments (1040-ES) | April 15, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Source: IRS Publication 509 and Form 1040-ES instructions, irs.gov.
Frequently asked questions
When are Delaware state taxes due in 2026?
Your 2025 Delaware individual income tax return is due April 30, 2026. If that date falls on a weekend or legal holiday, the deadline moves to the next business day. An extension moves the filing deadline to October 15, 2026, but any tax owed is still due on the original date.
When are Delaware estimated tax payments due in 2026?
Delaware estimated payments for the 2026 tax year are due April 30, 2026, June 15, 2026, September 15, 2026, January 15, 2027. Use Form PIT-EST (formerly Form 200-ES) or pay online. The final installment for 2025 was due January 15, 2026.
Does Delaware accept the federal extension?
No. File the state's own extension request. The state form is Form PIT-EXT. The extended filing deadline is October 15, 2026, and tax is still due by April 30, 2026.
Does a Delaware extension give me more time to pay?
No. An extension extends the time to file, not to pay. To avoid penalties and interest, pay what you expect to owe by April 30, 2026.
Dates are the statutory deadlines that fall in 2026 and move to the next business day when they land on a weekend or holiday. Each section links to the source it was checked against. Always confirm with the Delaware tax agency or the IRS before relying on a date. This is general information, not tax advice.