Tax Extensions: How Form 4868 Really Works (2025)

The single most misunderstood point

An extension buys you more time to file your paperwork — not more time to pay. This is the mistake that costs people money. Any tax you owe is still due on the original April deadline; the extension only protects you from the separate, larger failure-to-file penalty. This is spelled out in the IRS — About Form 4868 (Automatic Extension of Time to File).

How to get the extension

File Form 4868 by the April deadline — electronically through tax software or IRS Free File, or by making an extension payment through IRS Direct Pay and checking the extension box. Approval is automatic; you do not need a reason. You then have until mid-October 2026 to file your 2025 return.

Estimate and pay to avoid penalties

Because payment is still due in April, estimate your tax and pay as much as you can with the extension. The failure-to-pay penalty is 0.5% of unpaid tax per month plus interest — far cheaper than the 5%-per-month failure-to-file penalty, which is exactly what the extension eliminates.

When an extension makes sense

Extensions are useful when you are waiting on a corrected 1099 or K-1, dealing with a complex year, or simply need breathing room. They are routine and carry no stigma — millions are filed every year.

Automatic extensions for some taxpayers

U.S. citizens living abroad and members of the military in combat zones receive automatic extensions without filing Form 4868, and federally declared disaster areas often get postponed deadlines announced by the IRS.