An extension to file is not an extension to pay tax.
Form 4868, Application for Automatic Extension of Time to File U.S. Individual Income Tax Return, gives individual filers an automatic six-month extension to file Form 1040, 1040-NR, or a dual-status return. No reason or IRS approval is required.
The extension moves the filing deadline from April 15 to October 15. It does not extend the time to pay. Any tax not paid by the original April 15 due date accrues interest under IRC §6601 at the rate determined quarterly under IRC §6621, and is subject to the failure-to-pay penalty under IRC §6651(a)(2), generally 0.5% of the unpaid tax per month, up to 25%, even though the extension itself is valid and granted automatically.
Three ways to get the extension
Pay electronically and select "extension" as the reason. Using IRS Direct Pay, EFTPS, or a debit/credit/digital wallet payment and indicating the payment is for an extension automatically files the extension. No separate Form 4868 is required, and a confirmation number is issued.
E-file Form 4868 for free. IRS Free File allows anyone, regardless of income, to e-file Form 4868 electronically at no cost.
Mail a paper Form 4868. Estimate the tax liability on the form and mail it by the original due date. See how to paper file for current addresses and the timely-mailing rule.
Length and effect
Item
Detail
Automatic
Yes - no reason or IRS approval required
Original due date
April 15
Extended due date
October 15 (6 months)
Extends payment deadline
No - tax is still due April 15
Governing regulation
Treas. Reg. §1.6081-4
Estimate your tax liability as accurately as possible on Form 4868. An extension request can be denied retroactively if the IRS determines the estimate was not made in good faith, though this is rarely enforced when a reasonable, documented estimate is used.
Related special situations
Taxpayers living and working abroad on April 15 receive a separate automatic two-month extension with no form required, and taxpayers who need additional time to qualify for the foreign earned income exclusion can file Form 2350. See special situations for both.
Authority: IRC §6081(a); Treas. Reg. §1.6081-4 (26 CFR §1.6081-4, automatic extension of time for filing individual income tax return); IRC §6601; IRC §6621; IRC §6651(a)(2). Sources: irs.gov/forms-pubs/about-form-4868; irs.gov/filing/get-an-extension-to-file-your-tax-return; ecfr.gov 26 CFR 1.6081-4.
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