2026 IRS Tax Deadline Calculator
Find the exact 2026 deadline for your tax form. Automatically adjusts for weekends, federal holidays, and extension dates. Based on IRS Publication 509.
Tax Form & Date Checker
Form 1040 — Individual Return
All 2026 Key Dates
| Form / Event | Deadline |
|---|---|
| Form 1040 (Individual) | April 15, 2026 |
| Q1 Estimated Tax (1040-ES) | April 15, 2026 |
| Q2 Estimated Tax (1040-ES) | June 15, 2026 |
| S-Corp / Partnership (1120-S/1065) | March 15, 2026 → March 16, 2026 |
| C-Corporation (1120) | April 15, 2026 |
| Q3 Estimated Tax (1040-ES) | September 15, 2026 |
| S-Corp / Partnership Extension | September 15, 2026 |
| 1040 Extension | October 15, 2026 |
| Q4 Estimated Tax (1040-ES) | January 15, 2027 |
* Based on IRS Publication 509. Figures are for educational purposes and do not constitute professional tax advice.
Important 2026 IRS Deadline Notes
Weekend & Holiday Rule
Per IRC Section 7503, when the last day for filing a return falls on a Saturday, Sunday, or legal holiday, the filing deadline is automatically the next succeeding business day. This is non-negotiable and applies across all form types.
Emancipation Day (DC)
IRS headquarters is in Washington, DC. Emancipation Day (April 16) is a legal holiday in DC and can shift the April 15 deadline if it falls on a weekend. In 2026, April 15 is a Wednesday, so no shift applies.
Extension vs. Payment
An extension of time to file is not an extension of time to pay. You must estimate your tax liability and pay any amount owed by the original deadline. Failure to pay on time results in a 0.5% monthly penalty on the unpaid tax.
Quarterly Estimated Taxes
Form 1040-ES installments are due four times per year. Use our Quarterly Estimated Tax Calculator to compute your four payments and avoid the underpayment penalty.
IRS Tax Deadline FAQs
For 2026, the main deadlines are: April 15, 2026 — Form 1040 individual returns and Q1 estimated taxes; June 15, 2026 — Q2 estimated taxes; September 15, 2026 — Q3 estimated taxes and S-Corp/Partnership returns (Form 1120-S/1065); October 15, 2026 — extended individual returns; January 15, 2027 — Q4 estimated taxes.
Per IRS rules, if a tax deadline falls on a Saturday, Sunday, or legal holiday, the deadline is automatically extended to the next business day. This calculator adjusts for federal holidays (Emancipation Day in DC, etc.) automatically.
S-Corporation returns (Form 1120-S) and Partnership returns (Form 1065) are due by March 15, 2026. The deadline is extended to September 15, 2026 if you file for an extension. Note: Calendar-year C-Corporation returns (Form 1120) are due April 15, 2026.
File Form 4868 (Application for Automatic Extension of Time To File U.S. Individual Income Tax Return) by the original deadline (April 15). This grants an automatic 6-month extension to October 15, 2026. Remember — an extension to file is not an extension to pay. You must still estimate and pay any tax owed by the original deadline.
Emancipation Day is a legal holiday in the District of Columbia observed on April 16. Since IRS headquarters is in DC, if April 15 falls on a Friday and Emancipation Day falls on the following Saturday (observed Friday), the deadline may shift. This calculator accounts for federal holidays per IRS Publication 509.