Why a Postmark May Not Show the Day You Mailed Something

A U.S. Postal Service rule that took effect in December 2025 could create a longer delay between the day you mail something and the day it gets a postmark. CNBC says that matters for time-sensitive papers like tax returns and mail-in ballots.

The reason is that the Postal Service has been reorganizing, with fewer pickups at many locations and longer travel times for mail to reach the regional centers where postmarks are applied. It now expects bigger delays between sending and postmarking.

For taxes, the IRS generally treats a return as filed on the day it is postmarked. People who got a six-month extension had until October 15 to file. Anyone mailing a return can get a postmark that day by taking it to the post office for a manual postmark.

Mail-in ballots follow different rules, because states set their own. The National Conference of State Legislatures says that Thirty-five states need mail-in ballots to be turned in by the time Election Day ends. Washington, Guam, Puerto Rico, the Virgin Islands, and 15 other states usually allow votes to be counted if they are mailed by Election Day and reach officials within a few extra days. The date on your mail's postmark tells you when it was handled, but that might be different from the day you put it in the box. In California, ballots postmarked by Election Day can arrive up to seven days later and still count. Colorado requires them by 7 p.m. on Election Day.

About 1.2% of mail-in ballots in 2024 were rejected, the U.S. Election Assistance Commission says. Of those, 40.7% had a signature that did not match or was incomplete, 10% had no signature, and 17.8% arrived after the deadline.

Katy Owens Hubler of the NCSL said states choose different ways of doing things. The advice is to mail important papers early, and to check your state's deadline if it is a ballot.