Bill Oxford | Istock Unreleased | Getty Images
U.S. Postal Service postmark practices, formalized in a December 2025 rule, now often cause a delay between mailing and postmark—a gap that matters for tax returns, mail‑in ballots, and other time‑sensitive documents.
Two looming deadlines highlight the issue: October 15 for taxpayers who received a six‑month extension to file their federal returns, and November 3 for midterm election voters casting mail‑in ballots.
Taxpayers mailing a return can still meet the deadline by obtaining a manual postmark at the post office. By contrast, voters mailing midterm ballots generally cannot rely on the same rule.
The Internal Revenue Service treats a return as filed on the day it is postmarked, but most states require mail‑in ballots to be received by Election Day regardless of the postmark date. A postmark reflects when the postal service processed the mail, which may be later than the day the ballot was dropped in the mailbox.
Thirty‑five states require mailed absentee ballots to be received by Election Day, according to the National Conference of State Legislatures (NCSL). The remaining 15 states, plus Washington, D.C., Guam, Puerto Rico and the U.S. Virgin Islands, generally allow ballots postmarked by Election Day to arrive a few days later.
“State laws govern elections for the most part, and every state has chosen a little bit different way of doing things,” said Katy Owens Hubler, director of elections and redistricting for the NCSL.
About 1.2% of 2024 mail‑in ballots rejected
Nearly 48 million voters cast absentee ballots in the 2024 presidential election, accounting for about 30 % of the 158.2 million total votes, according to the U.S. Election Assistance Commission. This category includes traditional mail‑in ballots as well as those submitted via drop boxes or in person.
Roughly 1.2 % of mail‑in ballots were rejected in 2024, the commission reports. Signature mismatches or incomplete signatures accounted for 40.7 % of those rejections, while 10 % lacked a signature altogether. Another 17.8 % were discarded because they arrived after the state’s receipt deadline.
State deadlines differ widely. In California, ballots postmarked by Election Day may arrive up to seven days later and still be counted, NCSL notes. Colorado, however, requires ballots to be received by 7 p.m. on Election Day. Military and overseas voters often receive extra time for delivery.
A June Supreme Court decision affirmed that states may count ballots received after Election Day as long as they were cast on time and satisfy state‑specific deadlines.
Mail ballots a week before Election Day
Voters should be aware that delivery times can exceed expectations and that a postmark may not reflect the day a ballot was mailed.
The Postal Service’s recent operational changes—such as fewer pickup routes and longer transport times to processing centers—have extended the interval between mailing and postmark application. A December 2025 rule formalizes these longer delays.
Consequently, mail may not enter the processing stream until the following day, meaning the postmark will not appear on the day the item was dropped in the mailbox. Delays can be more pronounced around weekends or holidays, the Brookings Institution notes.
To mitigate the impact, the Postal Service announced “extraordinary measures” starting October 24 to accelerate ballot delivery, including additional trips to election offices. Beginning October 26, workers will hand‑postmark ballots that are delivered directly to local election offices or routed through postal hubs, according to a USPS memo.
“These things are going above and beyond what the Postal Service does for other pieces of mail,” said Tammy Patrick, chief programs officer at the National Association of Election Officials, a nonprofit organization for election administrators.
Even with these steps, there is no guarantee that a ballot will meet a state’s receipt deadline.
Patrick advises voters to mail their ballots at least a week before the deadline. If filing closer to Election Day and the state accepts a postmark as proof of timely submission, voters can visit any post office, request a manual postmark at the counter, and ensure the ballot is stamped.
Taxpayers can sidestep postmark concerns by filing electronically. For those who must mail a paper return, requesting a manual postmark at the counter or using certified mail provides additional proof of timely filing.