The United States Postal Service has adopted major changes to how postmarks are applied to mail. Because the Internal Revenue Service (“IRS”) and many state tax authorities, including the California Franchise Tax Board (“FTB”) rely on postmark dates to determine whether a return is timely filed, the changes could affect federal and state tax returns, extensions, payments, and other tax documents mailed after December 24, 2025.

If you plan on mailing your 2024 tax return, extension, or any IRS or FTB correspondence after December 24, 2025, you must follow new procedures to avoid your correspondence as being treated as late—even if you mailed your documents before the deadline.

What’s New

Under a final rule adopted by the USPS (FR Doc. 2025-20740), the date printed on a postmark will not reflect the date of the first automated processing scan — not the date mail is handed to the Post Office.

Because mail is often transported overnight to processing centers before being postmarked, your envelope may now receive a postmark dated one or more days after you mailed it.

This is a critical change because the IRS relies on the postmark date under Section 7502 of the Internal Revenue Code (“Code”) to determine whether your filing was timely.

Why This Matters for Taxpayers

Section 7502 of the Code provides that a tax return or payment is considered filed on time if the USPS postmark date is on or before the filing deadline.

But for returns mailed after December 24, 2025:

• Dropping your return in a mailbox on April 15 does not guarantee an April 15 postmark.
• If the envelope is postmarked April 16 or later, the IRS may treat your return as late filed— even if you deposited it earlier.

As of today, the IRS has issued no relief or guidance addressing this problem.

How to Protect Yourself

To ensure your federal and state tax returns receive a legally valid filing date, you must use one of the following in-person USPS retail methods:

Request a Manual (Local) Postmark

• Go to the USPS counter.
• Hand the envelope directly to the clerk.

Say:

• “I need a manual postmark on this item today.”

Manual postmarks are now expressly stated to be free of charge.

Use Certified Mail or Registered Mail (Recommended)

• Request certified or registered mail at the counter.
• Obtain a USPS-stamped receipt.
• A USPS-stamped certified or registered mail receipt remains the best evidence a tax return is timely filed, under the federal and state tax laws evidence of timely filing under Treasury Regulations.

Purchase a Certificate of Mailing

• Ask for a Certificate of Mailing at the counter.
• Keep the stamped receipt as proof of mailing date.

The Following Methods will not Protect You

The USPS rule now expressly states that the following do not prove when the IRS received your document:

• Click-N-Ship labels
• Self-Service Kiosk labels
• Metered postage
• Pre-printed customer postage labels
• These show only when postage was printed — not when USPS took possession.

Effective Date

The new USPS postmark rules become effective after December 24, 2025.  Any tax filings mailed after that date are subject to these rules.

Our Recommendation

If you are mailing any time-sensitive tax documents — including:

• 2024 income tax returns
• Extensions
• IRS appeals, protests, or Tax Court filings
• Payments to the IRS or FTB

Always appear at the Post Office counter and obtain a manual postmark or certified/registered mail receipt.

Bottom Line

Your tax return is no longer considered “filed” when you drop it in the mail — it is filed when the USPS decides to process it.

If you have questions about filing deadlines or need assistance preparing your filings, please contact Ascendant LLP before mailing any tax-sensitive documents.