IRS Communication and the USPS Postmark Rule

The United States Postal Service made an update to its postmark rule in 2025. It went into effect right before the year ended on December 24th, 2025. This update changes when the IRS will date the mail that they receive.

I've seen people discussing how this will affect absentee voting ballots, medication, and even those who pay bills by mail. But my main concern is for you, the taxpayer, and how this will affect communication with the IRS. The IRS has a mailbox rule that they use to consider when something was timely sent to them.

In this article, I will review how the USPS postmark rule has changed, the IRS mailbox rule, and how you can avoid any unnecessary penalties.

What is a Postmark?

A postmark is the manual stamp that the USPS puts on a piece of mail to indicate when the sender mailed it. When paying bills or mailing legal documents, this stamp is very important. It shows if the sender sent the information or payment timely.

What is the Old Postmark Rule?

The old postmark rule would have the USPS postmark the mail on the day that it was received. For example, if a person dropped off a piece of mail before the cutoff time for the day, the post office would postmark it with that date.

As a child, I can remember going to the post office with my father on April 15th and waiting in a long line. He and the other customers were waiting to receive their postmarks before the post office closed. That is because once the post office closes, its mail wouldn't receive an April 15th stamp. This is important because of the IRS mailbox rule, which we'll talk about a little later.

What is the new Postmark Rule?

The new postmark rule says that USPS will not stamp the mail when collected. Instead, they will postmark it once it reaches it begins automatic processing or reaches a regional facility. That could add a day or 2 to when the mail is actually postmarked.

Why is this a big deal? I live in Louisville, Ky, but I went to high school in Evansville, IN. That is where my parents and some friends of the family still live. Evansville is smaller and roughly 2 hours away. Since COVID, their mail now comes here to Louisville, and the USPS processes it here.

Under the new rules, if my Dad waits until April 15th to go to the office to mail his taxes and payment, the USPS won't stamp it until it reaches Louisville. Which would be at least the next day, April 16th.

This makes his tax return and his payment late. Which means the IRS will calculate both interest and a failure-to-pay penalty. But why?

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The IRS Mailbox Rule

In layman's terms, the IRS mailbox rule is that if the taxpayer is mailing a document, the US postmark is the date to use when determining if it is late or not. §7502 covers this in more detail. The IRS mailbox rule not only covers returns but also payments, statements, and refund claims filed on Form 3911 or Form 843.

This rule does not apply if the document was not actually delivered to the IRS. It must also be properly addressed and have the correct amount of postage. Proof of the mailing and postmark is important. Best practice is to send any correspondence to the IRS using certified mail. This has proof of the date sent as well as a tracking number to prove it arrived.

Best Practices for IRS Communication and USPS

If at all possible, use e-file to transmit returns. You can use DIY software such as 1040.com* if you'd like to submit them yourself. If not, your paid tax professional should be electronically filing unless there is a rejection where your return cannot be e-filed.

There are also online payment options through your IRS.gov taxpayer account. Things can change if the IRS has requested more information from you. When at all possible, use the IRS upload tools to send correspondence to the IRS.

If none of those options are available, make sure you do the following:

1. Take your mail to the counter and request that they stamp it there.

2. Send your mail to the IRS via Certified Mail so that you have proof that you sent it and you can track it.

3. Put your certified receipt in a place with all of your other IRS correspondence for that tax year/form.

In Summary

The updated USPS postmark rule can cause you to incur IRS penalties and interest if you don't mail things timely. If at all possible, avoid communicating with the IRS via mail. When you do communicate via mail, be sure to send your information using certified mail.

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*Timalyn is an affiliate of 1040.com and will receive a commission should you decide to use her affiliate link.

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Timalyn S. Bowens EA is America's Favorite EA and Tax Expert who will work hard to find a customized legal solution for you! As an Enrolled Agent licensed through the Internal Revenue Service, Timalyn can fight the IRS for taxpayers in all 50 states. As the host of Tax Relief with Timalyn Bowens and a YouTube content creator, she empowers taxpayers to make educated decisions about their tax situation.

When you are facing questions regarding your personal or business taxes, working with a professional makes all the difference. At Bowens Tax Solutions, we serve our Louisville-area neighbors by providing the tax services and knowledge needed to succeed. We are here to assist you with your tax issues and preventative care. Visit our website at www.bowenstaxsolutions.com for more information.