Deadlines · calculator
Federal tax deadlines for 2026 and 2027
The dates that matter between now and the April 2027 filing deadline, and the penalties behind them.
Cost of filing or paying late
Penalties and interest
$670
On $4,000 unpaid for 3 months
- Failure-to-file penalty$540
- Failure-to-pay penalty$60
- Interest at 7% a year, compounded daily$70
An extension moves the filing date, not the payment date. Interest uses the current quarterly rate for the whole period; the IRS applies each quarter’s rate.
The federal return for tax year 2025 was due April 15, 2026; taxpayers who requested the automatic extension have until October 15, 2026 to file it, though any tax due should have been paid in April. The return for tax year 2026 is due April 15, 2027, which is also the last day to request an extension to October 15, 2027, to pay the 2026 balance and to make 2026 contributions to an IRA or HSA. Estimated tax for 2026 is paid in four installments, on April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027, according to the 2026 Form 1040-ES. Missing the filing deadline without an extension costs 5% of the unpaid tax for each month or part of a month, up to 25%; paying late costs 0.5% a month, also capped at 25%, plus interest compounded daily. Someone who owes $3,000 and files and pays three months late would face about $580 of penalties before interest. If no tax is owed, a late return brings no failure-to-file penalty, since it is computed on unpaid tax.
Checked by Radif Partners · Editorial policy · How we calculate
The calendar from October 2026 to October 2027
| Date | What is due |
|---|---|
| October 15, 2026 | 2025 returns filed under an automatic extension (Form 4868) |
| January 15, 2027 | Fourth 2026 estimated payment (skip it if you file and pay by February 1, 2027) |
| Late January 2027 | IRS starts accepting 2026 returns (date announced in January) |
| April 15, 2027 | 2026 return and payment; extension request; 2026 IRA and HSA contributions; first 2027 estimated payment |
| October 15, 2027 | 2026 returns filed under an extension |
How the penalties add up
The two penalties run side by side. For each month or part of a month the return is late, 5% of the unpaid tax, reduced by the 0.5% failure-to-pay penalty of the same month, so 4.5% plus 0.5%. After five months the failure-to-file part reaches its 25% ceiling; the failure-to-pay part keeps running until it too reaches 25%. Interest is charged on the tax and on the penalties at the quarterly underpayment rate, 7% for the last quarter of 2026. With an approved payment plan after an on-time return, the failure-to-pay rate drops to 0.25% a month.
Filing on time but paying later costs far less: someone who owed $3,000 on the 2025 return, filed by the deadline or under extension and paid six months late, faces about $90 of failure-to-pay penalty plus interest. That is why the IRS insists on filing on time even when you cannot pay.
Extensions and estimated payments
An extension gives six more months to file, not to pay. Estimated payments are due from people whose withholding will not cover their tax, typically the self-employed, landlords and investors; the estimated tax calculator shows the safe harbors. The interest rate page explains how interest accrues on any unpaid balance.
Sources: IRS: When to file (April 15, 2026 due date, automatic six-month extension); IRS Form 1040-ES (2026), Estimated Tax for Individuals: What's New and due dates; IRS: Failure to file penalty; IRS: Failure to pay penalty; IRS Rev. Proc. 2025-32: 2026 inflation-adjusted items and 2025 items modified by Public Law 119-21 (October 9, 2025), read on October 11, 2026.