USPS has Changed Postmark Date--Be Aware!

February 9th, 2026 at 7:40 AM

For decades, taxpayers trusted a simple rule: if you mailed a tax return or payment by the deadline, the IRS treated it as timely filed. Recent U.S. Postal Service (USPS) practices have changed that reality and created a serious trap for anyone who relies on last-minute mailing.

Today, the USPS often applies postmarks at regional processing centers instead of at your local post office. Those centers may be many miles away, and reduced truck schedules can delay transport.

As a result, a return you drop off on April 15 may receive a postmark dated April 16 or later. The IRS will then treat your filing as late, even though you acted responsibly. Being one day late can trigger penalties and interest equal to 5 percent of the tax due.

Sometimes, USPS postmark machines don’t even apply a postmark.

You also cannot rely on postage labels printed at home or at self-service kiosks. Those labels only show when you bought postage, not when the USPS accepted your mail.

You can protect yourself by taking control of the mailing process. Present your return at a post office retail counter and ask the clerk to apply a manual postmark. For stronger protection, use certified mail. Certified mail provides a postmarked receipt that serves as legal proof of mailing and delivery.

You also have legal proof by filing and paying electronically or by using an IRS-approved private delivery service. Electronic filing provides an electronic postmark and removes uncertainty.

If you plan to file by mail, choose your method carefully. A small decision can prevent an expensive and frustrating surprise.

Mark S. Fineberg, CPA