Mailing Return Last Minute Now a Risky Business

Taxpayers who rely on last minute trips to the post office may be taking a bigger risk this year, thanks to a quiet but consequential change by the U.S. Postal Service (USPS).

In December, the USPS altered how it postmarks mailed documents—a shift that could determine whether a tax return or payment is considered on time or late. Previously, mailed tax documents were postmarked on the date they were received at a local post office. Under the new rules, the postmark is applied when the document reaches a regional processing facility, which can be one or more days later.

That delay matters. The Internal Revenue Service treats a tax document as timely filed or paid only if the postmark date is on or before the official deadline. A later postmark—even if the envelope was dropped off on time—can trigger late filing or late payment penalties.

Tax professionals say the change effectively shortens the margin for error for anyone mailing tax documents close to the deadline. Recommended alternatives include: filing and paying electronically, using certified or registered mail, requesting a manual postmark at the post office counter, mailing documents well in advance, or using approved private delivery services such as FedEx, UPS, or DHL, which provide proof of delivery equivalent to a postmark.