Tax Filing Deadlines and Extensions

For individual federal returns the calendar is the same every year, with the dates moving only when 15 April falls on a weekend or holiday. The return for tax year 2026 is due on Thursday, 15 April 2027. That is the date to file, to pay, or to request an extension. The return for tax year 2025 was due on 15 April 2026. The single most misunderstood point on this page is that an extension extends the time to file, never the time to pay.

The 15 April deadline

The individual return for tax year 2026 is due on Thursday, 15 April 2027. By that date you must have filed the return, paid the tax owed, or filed Form 4868 to extend the filing deadline. The same date is the deadline for IRA contributions for the tax year, and that deadline is not extended by Form 4868. A SEP IRA contribution deadline does follow the extended return date, which is a useful exception for self-employed savers.

If 15 April falls on a weekend or a holiday in the District of Columbia, the deadline moves to the next business day, which is why the date is sometimes 16 or 17 April. For 2027 the date is a Thursday and no such move applies.

Form 4868: the six-month extension

Form 4868 gives an automatic six-month extension of time to file, to 15 October 2027 for a 2026 return, and to 15 October 2026 for a 2025 return. No IRS approval is needed if it is filed on time, and no reason is required. You can file it electronically through tax software or the IRS Free File system, or on paper.

The extension is automatic, but it is not free. You must estimate the tax you owe and pay it with the extension, because any unpaid balance after 15 April accrues interest and the failure-to-pay penalty. An extension filed without payment is still valid as an extension, but the bill keeps growing while you wait.

Filing late vs paying late

The penalties for filing late and paying late are very different, which is why filing on time matters even when you cannot pay. The failure-to-file penalty is 5% of the unpaid tax per month or part of a month, up to 25%. The failure-to-pay penalty is 0.5% per month, up to 25%. Filing late costs ten times as much per month as paying late.

Interest also accrues on unpaid tax. The underpayment interest rate for individuals was 7% per year in the fourth quarter of 2026, and 6% per year in the second quarter of 2026, and it is reset quarterly. Interest runs from the original due date until the balance is paid, and it is not stopped by an extension.

Americans abroad

Americans living abroad get an automatic two-month extension to 15 June 2027, to file and to pay, with no form required, although a statement should be attached to the return. Interest still accrues from 15 April on any unpaid balance. A further extension to 15 December 2027 is available by letter, at the discretion of the IRS.

The two-month extension is automatic, but it is easy to miss the interest point. The extra two months cost nothing in penalties, but interest runs from 15 April, so paying by 15 April is still cheaper even when filing can wait until June.

A practical calendar

Put three dates on the calendar. First, 15 April: file, pay, or extend, and make the IRA contribution. Second, 15 June: the deadline for Americans abroad, and the second estimated tax payment. Third, 15 October: the extended filing deadline. If you file an extension, do not treat October as a new April. The work is the same, the bill has been growing since April, and the extension does not protect you from that.

And if you cannot pay in full by 15 April, file anyway. The failure-to-file penalty is the expensive one, and filing on time is the cheapest thing you can do. Payment options for people who owe more than they can pay are covered in the paying the IRS guide.

Sources: Internal Revenue Service, Form 4868 instructions and filing deadline guidance, https://www.irs.gov/newsroom/irs-releases-tax-inflation-adjustments-for-tax-year-2026-including-amendments-from-the-one-big-beautiful-bill; IRS underpayment interest rate announcements.