How to File a Tax Extension for Married Couples: Form 4868

Married couples can file a federal tax extension by submitting Form 4868 to the IRS by April 15. If you plan to file a joint return, you send one form with both spouses’ names and Social Security numbers. If you plan to file separately, each spouse sends their own. The extension gives you until October 15 to file the return, but any tax you owe is still due on April 15.¹

One Form for a Joint Return, Two for Separate Returns

For couples planning a joint return, a single Form 4868 covers both spouses. List the names in the same order you’ll use on Form 1040, put the first spouse’s Social Security number on Line 2, and put the second spouse’s SSN on Line 3.² The estimated tax numbers on Lines 4 through 7 reflect your combined household income and payments.

Couples filing as Married Filing Separately each submit their own Form 4868. Each form should show only that spouse’s estimated income, withholding, and payments. Splitting those figures takes some care when income comes from jointly held investments or a shared business.

The filing status you use on the extension does not lock you in. You can file a joint extension and later submit separate returns, or file separate extensions and later combine into a joint return.² If you switch from a joint extension to separate returns, the payment made with Form 4868 can be applied to either return or split between them however you agree. That flexibility is a good reason to go ahead and file the extension while you sort out which status makes more sense.

Estimating What You Owe

Form 4868 asks for four numbers: estimated total tax liability on Line 4, total payments already made through withholding and estimated tax on Line 5, the balance due on Line 6 (Line 4 minus Line 5), and the amount you’re paying with the extension on Line 7.² Your estimate of total tax should include income tax, self-employment tax, and anything else that would appear on Form 1040.

The cleanest starting point is last year’s return. Pull your prior-year tax liability and adjust for what changed: a raise, a job loss, stock sales, rental income, a new child. Couples with straightforward W-2 income can usually get close by comparing year-end pay stubs to last year’s Form 1040. When income comes from self-employment, capital gains, or year-end bonuses, the estimate gets harder and the stakes go up.

Err on the side of paying slightly more than you think you owe. Overpay and the IRS refunds the difference when you file. Underpay and you face a failure-to-pay penalty on the shortfall. Paying at least 90% of your actual tax liability by April 15, with the rest sent when you file, keeps you clear of the failure-to-pay penalty during the extension period.³

Three Ways to Submit the Extension

E-File Form 4868

The fastest option. Most commercial tax software files the extension electronically, and you get immediate confirmation that the IRS received it. You can also e-file through IRS Free File if your adjusted gross income is $89,000 or less.⁴ E-filing lets you authorize an electronic funds withdrawal from your bank account at the same time, handling both the extension request and the payment in one step.¹

Make a Payment and Skip the Form

You can request an extension simply by making a payment through IRS Direct Pay and selecting “extension” as the payment type. That counts as filing for an extension without separately submitting Form 4868.⁵ The same works with a debit card, credit card, or digital wallet through an IRS-approved payment processor. If you already know you owe, a single transaction handles both the extension and the payment.

Mail a Paper Form 4868

If you prefer paper, fill out Form 4868 and mail it to the IRS service center for your state. Check the current year’s instructions for the right address; the designated center varies by location. The envelope must be postmarked by April 15 to count as timely filed.⁶ If you’re mailing a payment with the form, include a check or money order payable to “United States Treasury” with both SSNs, the tax year, and “Form 4868” written on it.

Paying by April 15

However you file the extension, the estimated balance on Line 6 needs to reach the IRS by the original April deadline. The main payment methods:

IRS Direct Pay, a free bank-account transfer through irs.gov. You’ll need your bank routing and account numbers, and payments process in one to two business days.
Electronic funds withdrawal when e-filing Form 4868, pulled from your bank account on a date you choose up to the deadline.
Credit or debit card through an IRS-approved third-party vendor. Credit card payments carry a processing fee, typically around 1.85% to 1.98% of the amount.
Check or money order mailed to the correct IRS service center, with your names, SSNs, tax year, and “Form 4868” written on the payment so the IRS can match it to your account.

What Happens If You Don’t Pay Enough

The extension postpones your filing deadline, not your payment deadline. If you owe money and don’t pay by April 15, the IRS charges a failure-to-pay penalty of 0.5% of the unpaid balance for each month or partial month the tax goes unpaid, up to 25%.⁷ Interest also accrues on the unpaid amount from April 15 until the balance is cleared. The IRS sets that rate quarterly at the federal short-term rate plus three percentage points; for the first quarter of 2026, the rate is 7% per year, compounded daily.⁸

You can avoid the failure-to-pay penalty during the extension period if you’ve paid at least 90% of your actual tax liability by April 15 and pay the rest when you file.³ Interest still runs on any unpaid amount, but the penalty itself goes away.

Even if you can’t pay anything on April 15, file the extension anyway. The failure-to-file penalty is much steeper: 5% of the unpaid tax per month, up to 25%, with a minimum of $525 or 100% of the unpaid tax (whichever is less) if you file more than 60 days late.⁹ The extension eliminates that penalty entirely as long as you file by October 15.

Couples Living Abroad or on Military Duty

If both spouses live outside the United States and Puerto Rico on April 15, or either spouse is on military duty outside the country, you get an automatic two-month extension to June 15 without filing any form. You do need to attach a statement to your return explaining which situation qualified you.¹⁰ Interest on any unpaid tax still runs from April 15. If you need more time beyond June 15, you can still file Form 4868 to extend to October 15.

Service members deployed to a combat zone, and their spouses, receive broader relief. The filing and payment deadlines are pushed back for the entire period of service in the combat zone, plus 180 days after the last day in the zone, plus however many days remained before April 15 when the service member entered. Unlike most extensions, this one also extends the time to pay, so no interest or penalties accrue during the extension period. Spouses receive the same deadline relief, with limited exceptions for hospitalizations inside the United States or combat zone designations that ended more than two years earlier.¹¹

State Extensions Are Separate

A federal extension does not automatically cover your state return in every state. Some states honor the federal extension automatically, some require a separate state form, and others grant their own automatic extension independently. Check your state revenue department’s website before assuming you’re covered. Regardless of how a state handles the paperwork, nearly all states still expect estimated tax payments by the original state deadline to avoid state-level penalties and interest.

After the Extension Is Accepted

Your new filing deadline is October 15. Mark it. The IRS does not send reminders, and there is no second extension for individual filers. If you e-filed, save the confirmation number. If you mailed the form, keep your proof of mailing.

Use the extra months to gather what slowed you down: a late K-1, brokerage statements with cost-basis corrections, records for a home-office deduction. If your financial picture shifts between April and October and you realize you underpaid, make an additional payment through IRS Direct Pay to reduce the interest running on the balance.⁵ The sooner you pay, the less interest accrues.

1
Internal Revenue Service. Topic No. 304, Extensions of Time to File Your Tax Return
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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. Avoiding Penalties and the Tax Gap
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Internal Revenue Service. E-File: Do Your Taxes for Free
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Internal Revenue Service. Types of Payments Available to Individuals Through Direct Pay
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Internal Revenue Service. Topic No. 301, When, How and Where to File
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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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Internal Revenue Service. Failure to File Penalty
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Internal Revenue Service. Automatic 2-Month Extension of Time to File
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Internal Revenue Service. Extension of Deadlines – Combat Zone Service