What taxpayers, voters should know

U.S. Postal Service postmark practices that were formalized in a December 2025 rule could mean a longer delay between when something is mailed and when it’s postmarked — a distinction that matters for tax returns, mail-in ballots and other time-sensitive documents.

The issue may crop up as two deadlines approach: Oct. 15 for taxpayers who received a six-month extension to file their federal income tax returns, and Nov. 3 for voters casting ballots in the midterm elections.

Taxpayers who mail their return can meet Thursday’s deadline by taking it to the post office for a manual postmark. But voters casting ballots by mail for the midterms can’t necessarily count on the same rule.

That’s because while the IRS generally considers a return filed on the day it is postmarked, most states require mail-in ballots to arrive by Election Day, regardless of when they were mailed or postmarked. A postmark shows the date your mail was processed, which may not be the day you mailed the ballot. 

Thirty-five states require mailed absentee ballots to be received by election officials on or before Election Day, according to the National Conference of State Legislatures, a bipartisan organization that tracks state laws and policies. The other 15 states — along with Washington, Guam, Puerto Rico and the Virgin Islands — generally allow ballots postmarked by Election Day to arrive afterward, usually within a specified number of days.

“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.

Nearly 48 million voters cast absentee ballots in the 2024 presidential election, representing roughly 30% of the total 158.2 million ballots cast, according to the U.S. Election Assistance Commission. The absentee figure includes mail-in ballots as well as those returned through drop boxes or in person.

About 1.2% of the mail-in ballots cast in 2024 were rejected, according to the commission. Of them, 40.7% were rejected because the signature on the return envelope didn’t match the one on file or was incomplete, and 10% were rejected because they lacked any signature. Another 17.8% were rejected because they were not received by the state’s deadline.

Those deadlines vary from state to state. In California, for instance, mail-in ballots postmarked by Election Day can arrive as many as seven days afterward and still be counted, according to NCSL. Colorado, by contrast, requires mail-in ballots to be received by 7 p.m. on Election Day. Some states give military and overseas voters additional time for ballots to arrive after Election Day.

In a June ruling, the Supreme Court upheld states’ authority to count mail-in ballots received after Election Day, provided they were cast on time and meet state deadlines.