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IRS Tax Filing Warning Issued Ahead of Deadline

A change in postmark policy could cause you to miss a key tax deadline.

By Paige Cerulli , Edited by Laura Hohenstein

Updated April 20, 2026

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Tax season can feel chaotic, but filing your taxes by the deadline can lower your financial stress and is one less thing for you to worry about. If you're someone who mails your taxes on the April 15 deadline, you might need to rethink your strategy this year.

The National Taxpayer Advocate is warning taxpayers that recent USPS postmark rule changes could cause your tax return or payment to be classified as late, even if you technically mailed it on April 15. Here's what you need to know to avoid potential penalties and fees.

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How the tax deadline works

The 2026 deadline to file your taxes and pay any owed taxes is April 15. The IRS uses the postal code to determine if you've mailed your taxes on time. If the return or payment is postmarked on or before April 15, then it's considered to be on time. But if that postmark is later than the 15th, the IRS considers you to have filed late, and you could face fees because of it.

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How postmarks have changed

On December 24, 2025, a new USPS rule regarding postmarks went into effect, and it could spell trouble for taxpayers. Previously, mail was postmarked on the day that you put it in a mailbox or gave it to a mail carrier. Under the new rule, the postmark could reflect when the mail is processed at a USPS facility, meaning the postmark could be a day or days after you actually mailed your tax return. The postmark discrepancy issue is more common in rural areas where mail has to travel farther to reach a processing and distribution facility.

For example, let's say you drop your tax return in a USPS blue mailbox. Depending on when the mail is picked up from the mailbox and if there is a Sunday within the timeline, the mail might not reach a sorting facility for one to three days after you sent it. If you mailed your return on April 15, the postmark might reflect a later date, and your return would technically be late.

How to protect yourself from the postmark issue

If possible, consider e-filing your tax return. When you e-file, you'll receive a confirmation right away, and you don't have to worry about a postmark.

Some forms aren't eligible for e-filing, and you may prefer to file a paper copy of your taxes. If you mail your taxes, go to a USPS counter and use Certified Mail, Registered Mail, or Postage Validation Imprint. These services will give you proof that you mailed your taxes, and the postmark date will be the same date that you mail the document. Keep a copy of your receipt in case any questions about when you mailed your taxes arise.

How tax extensions work

If you won't have time to gather all of your tax paperwork or your accountant won't be able to complete your tax return by the April 15 deadline, you can file a tax extension. The extension gives you an additional six months to file your tax return by October 15, 2026.

You will need to submit IRS Tax Form 4868 by April 15 to request an extension. You can e-file or mail the form.

A tax extension only gives you more time to file your return, and you must still pay any owed taxes by April 15. You will need to include payment for any owed taxes when you request an extension, or you could face interest and penalties.

What to do if you can't pay your taxes in full by April 15

If you cannot pay your taxes in full, pay what you can for now, and request a payment plan from the IRS. You can apply online or by phone, or you can submit Form 9465 to request a payment plan.

A payment plan gives you more time to pay the taxes you owe. Short-term payment plans give you 180 days to pay your taxes, and there are no setup fees, but you will pay accrued penalties and interest. Long-term payment plans carry varying setup fees, plus accrued penalties and interest.

What to know about the paper check phase-out

As of September 30, 2025, the IRS is phasing out the use of paper checks to provide tax refunds. Doing so speeds up the delivery processing time, improves security and fraud prevention, and saves money.

If you received a paper check refund from the IRS last year, then you should receive communication from the IRS encouraging you to create or update your IRS online account. You will need to provide banking information, including your routing number and account number, to receive your electronic tax refund.

If you don't have a bank account and don't wish to open one, you can choose to receive your refund via an alternative method, such as through a prepaid debit card or a digital wallet.

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Bottom line

The rules around filing your taxes often change, so it's important to stay informed to ensure you file your taxes correctly. A tax professional can help guide you through the process, but you can also use IRS.gov if you need help filing your taxes or want to track your tax refund.

Keep the postmark policy change in mind as you file your taxes this season, too. Doing so can help you avoid potential fees and put extra cash in your pocket.

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Author Details

Paige Cerulli

Paige Cerulli is a writer for FinanceBuzz with more than 15 years of experience covering personal finance. She focuses on trending financial topics and helps readers make sense of everyday money decisions to more timely topics like tax refunds and how to make the most of that extra cash.