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If you’re planning to mail your 2025 tax return this year, one detail could make the difference between filing it on time and missing it: the postmark.
April 15 is the deadline for federal (and most state) taxes, but the IRS considers any tax return postmarked on or before that date to be filed on time, even if it’s not received by the agency until several days later. The postmark indicates the date the mail was processed and previously applied on the same day you mailed the item.
However, due to ongoing changes in the operations of the United States Postal Service, the postmark of the day the item is mailed may differ from the applicable date.
“The crux of the problem is that taxpayers assume that the day they put their return in the mail is the day it will be postmarked,” said Joshua Youngblood, founder of The Youngblood Group in Dallas and an IRS registered agent. “That was never guaranteed, but it’s more important now than ever.”
Reasons why postmarks may be delayed
The Postal Service expects delays between mailing and postmarking to increase as it continues a multiyear overhaul of its operations to strengthen its finances and modernize its infrastructure, according to rules published in the Federal Register that took effect Dec. 24.
Because pickups at many post offices have decreased and travel time has increased for mail to reach the local processing center where the postmark applies, “the postmark date does not inherently or necessarily coincide with the date on which the mail is first accepted into possession by the postmark,” the rule says.
The Postal Service said in a notice that it will not change the way mail is postmarked, which has always been done at postal processing facilities, but the agency added language to the Domestic Postal Manual to clarify the issue.
Part of the problem, according to a study published in December by the Brookings Institution, is that due to changes in transportation schedules and consolidation of processing facilities, many post offices that previously sent mail to hubs twice a day are now sending mail only once in the morning. Additionally, research shows that approximately 26% of post offices are located within 50 miles of a regional center, and another 26% are located between 150 and 500 miles away.
The bottom line is that some mail typically doesn’t start moving through the system until at least the next day. In that case, the postmark will not reflect the date the item was mailed. In some cases, such as before weekends or holidays, it may take longer to apply.
“To ensure your tax return is postmarked the same day it is mailed, ask a retail post office clerk to manually cancel your return for free,” the Postal Service advises on its website.
Approximately 11 million tax returns were not filed electronically last year.
While more households are turning to digital options to file taxes, pay bills, and handle other personal business, some still rely on the Postal Service to mail time-sensitive items like tax returns.
So far in 2026, through March 27, the IRS has received 88.4 million tax returns. Of those, 1.6 million were not submitted electronically. According to the IRS, of the 165.8 million tax returns the IRS received in 2025, approximately 10.9 million were not electronically filed.
For individual tax returns (Form 1040), the late filing penalty is 5% of the tax owed for each month or partial month in which the return is filed late, up to a maximum of 25%. In addition, the penalty for late payments is 0.5% of the outstanding balance per month, again capped at 25%. Interest will also accrue on unpaid balances at the federal short-term interest rate plus 3% daily.
However, if you have filed and paid your taxes on time for the past three years, you can request that the penalty be waived, Youngblood said.
Here are some options to help you arrive on time
If you plan to mail your tax return, don’t rely on metered postage or self-service kiosk labels, he said.
“These indicate when the postage was printed, not when (the Post Office) owned it,” Youngblood said.
Youngblood said it’s free to ask a postal worker to manually postmark your tax return, but you can also consider using certified mail, which costs $5.30.
“This provides both proof of mailing and a reliable date stamp,” he said. “This is the gold standard for anyone mailing something time-sensitive to the IRS.”
Alternatively, a certificate of mailing to keep for your records costs $2.40 and shows the date you mailed something. Youngblood said there are also private delivery services available for the IRS to pick up letters from.
