How to File Form 4868: Methods, Deadlines, and the 90% Rule

To file Form 4868 and get an automatic six-month extension on your federal income tax return, submit the form electronically through IRS Free File or commercial tax software, make an extension-designated tax payment that stands in for the form, or mail a completed paper Form 4868 postmarked by April 15. The extension moves your filing deadline to October 15, but it does not extend your time to pay. The IRS still expects at least 90% of what you owe by the original April deadline.

The Three Ways to File

Electronic Filing

IRS Free File lets any taxpayer submit Form 4868 electronically at no cost, regardless of income.¹ Commercial tax software includes the same tool. You’ll receive an electronic acknowledgment (or a rejection notice) confirming the IRS got it, usually within about 24 hours.²

Pay and Skip the Form

You can bypass Form 4868 entirely by making a tax payment and selecting “extension” as the reason. The payment itself triggers the extension. This works through IRS Direct Pay, the Electronic Federal Tax Payment System (EFTPS), or a credit card, debit card, or digital wallet. For card and digital wallet payments, even $1 counts as a qualifying payment.³ The confirmation number you receive is your proof of extension.⁴

Paper by Mail

Print Form 4868 from the IRS website, fill it in, and mail it to the processing center listed for your state in the form’s instructions. The right address depends on where you live and whether you’re enclosing a payment.⁵ The envelope must be postmarked by April 15. If you’re using a private carrier instead of the Postal Service, only certain services from DHL Express, FedEx, and UPS qualify for the timely-mailed rule; standard ground shipping does not.⁶

What Goes on the Form

Part I is basic identification: your name, current mailing address, and Social Security Number (or ITIN). Joint filers include the same information for both spouses so the IRS can match the extension to both accounts.²

Part II asks for three numbers:

Your estimated total tax liability for the year after credits.
Total payments you’ve already made, including employer withholding and any quarterly estimated payments.
The balance due, which is the difference between those two figures, reported on line 6.

The estimate doesn’t need to be exact, but it can’t be a wild guess. The IRS uses this number to decide whether you’ve met the 90% threshold that keeps penalties from stacking up during the extension. Lowballing to avoid writing a check now sets you up for penalties later.

The 90% Rule: Pay When You File the Extension

Filing Form 4868 extends your time to file, not your time to pay. Interest starts accruing on any unpaid balance after April 15 regardless of the extension.⁷

The threshold that matters: if you pay at least 90% of your actual tax liability by April 15 (through withholding, estimated payments, or a payment sent with your extension) and cover the remainder when you file, the IRS treats the late payment as having reasonable cause. That shields you from the failure-to-pay penalty during the extension period.⁵ Fall short of 90%, and the 0.5%-per-month failure-to-pay penalty applies to the shortfall from April 15 forward.⁸

Interest at 7% per year, compounded daily, applies to any unpaid balance after the original deadline whether or not you’ve met the 90% threshold.⁹ The IRS adjusts the rate quarterly.

Even if you can’t pay anything, file the extension anyway. The failure-to-file penalty runs at 5% of unpaid tax per month, ten times the failure-to-pay rate.¹⁰ Form 4868 eliminates that penalty entirely by moving your deadline to October 15.

Key Deadlines for 2026

For the 2025 tax year filed in 2026:

April 15, 2026 is the last day to submit Form 4868 or make a payment-based extension request, and the last day to pay without triggering interest.
October 15, 2026 is the extended filing deadline, the absolute cutoff for submitting your completed return without facing failure-to-file penalties.²

Both dates fall on weekdays in 2026, so no shift applies. When either date lands on a weekend or federal holiday in a given year, the deadline moves to the next business day.

After You Submit

The IRS doesn’t send a formal approval letter. Extensions are automatic as long as the form is complete and timely, so no news is good news.⁷ Electronic filers get an acknowledgment or rejection within about 24 hours.

A rejection is almost always a data-entry problem: a mistyped Social Security Number, a misspelled name, or a mismatch because someone else already filed using the same SSN, which can indicate a duplicate filing or identity theft.¹¹ Correct the error and resubmit. If it’s too close to the deadline to fix electronically, print and mail a paper Form 4868 before midnight on April 15 as a backup.

If You Can’t Pay What You Owe

Send as much as you can with the extension to shrink the interest and any penalty exposure, then look into a payment plan once you file. The IRS offers two:

A short-term payment plan for balances under $100,000, giving you up to 180 days to pay in full. No setup fee if you apply online.¹²
A long-term installment agreement for balances up to $50,000 including penalties and interest, paid monthly. Setup fees range from $22 to $178 depending on the application method, and low-income taxpayers can get the fee waived.¹²

An approved installment agreement cuts the failure-to-pay penalty rate from 0.5% to 0.25% per month, though interest keeps accruing until the balance is gone.⁸ Apply online through your IRS account or by mailing Form 9465.

If You’re Living Abroad

U.S. citizens and resident aliens whose main place of business or duty station is outside the U.S. and Puerto Rico on April 15 get an automatic two-month extension to June 15 without filing anything. The same applies to military members serving overseas. Attach a statement to your return explaining which situation applies; for joint filers, only one spouse needs to qualify. If you need still more time, file Form 4868 to push the deadline to October 15.¹³ The two-month extension covers filing only. Interest on any unpaid balance still runs from April 15.

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Internal Revenue Service. Get an Extension to File Your Tax Return
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Internal Revenue Service. About Form 4868, Application for Automatic Extension of Time to File U.S. Individual Income Tax Return
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Internal Revenue Service. Pay by Debit or Credit Card When You E-File
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Internal Revenue Service. IRS: Need More Time to File, Request an Extension
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Internal Revenue Service. Form 4868, Application for Automatic Extension of Time to File U.S. Individual Income Tax Return
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Internal Revenue Service. Private Delivery Services (PDS)
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eCFR. 26 CFR 1.6081-4 – Automatic Extension of Time for Filing Individual Income Tax Return
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Internal Revenue Service. Failure to Pay Penalty
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Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026
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Office of the Law Revision Counsel. 26 U.S. Code 6651 – Failure to File Tax Return or to Pay Tax
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Internal Revenue Service. Age, Name or SSN Rejects, Errors, Correction Procedures
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Internal Revenue Service. Payment Plans; Installment Agreements
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Internal Revenue Service. U.S. Citizens and Resident Aliens Abroad – Automatic 2-Month Extension of Time to File