A filing extension does not extend the time to pay

Requesting an extension is normal and sometimes prudent, for example when a K-1 or a foreign document is missing. But there is a common mistake: believing the extension also gives more time to pay.

What it extends

Form 4868 extends the deadline to file the individual return to October 15. It does not extend the deadline to pay, which is still April 15.

What happens if you do not pay in April

Interest runs on the unpaid balance from April 15, plus a late-payment penalty of half a percent per month. That is why, when requesting the extension, you should estimate the tax and pay it, even approximately.

Why it is still worth requesting

If neither the return nor the extension is filed, the failure-to-file penalty is much larger: five percent per month, up to 25%. With the extension, that penalty goes away even if you have not paid everything yet.

Special cases

A nonresident who did not receive wages subject to withholding has until June 15 to file Form 1040-NR. A citizen or resident living outside the United States automatically gets two extra months, although interest runs from April.

If you cannot pay in full

File anyway and pay what you can. The IRS offers payment plans, and it is better to request one on time than to wait for a collection notice.