Postmarks No Longer Guarantee Proof of Mailing Date

A significant change in U.S. Postal Service operations could create serious complications for taxpayers and businesses who rely on postmarks to prove compliance with critical deadlines. As of December 24, 2025, postmarks can no longer be considered reliable evidence of when mail was sent, potentially putting tax returns, legal documents, and other time-sensitive correspondence at risk.

What Changed at the USPS

The postal service has implemented sweeping operational changes under its "Delivering for America" plan, fundamentally altering how mail is processed and postmarked. These changes include:

• Consolidation of processing centers - Nearly 200 local facilities reduced to just 60 regional centers

• Increased distances - Nearly half of post offices are now more than 100 miles from their processing center

• Delayed postmarking - Mail may not receive official postmarks until it reaches distant regional facilities

The result: A growing gap between when you drop off mail and when it receives an official postmark, especially in rural areas where delays of a day or more are becoming common.

This change affects more than just tax deadlines. Court filings, insurance claims, contract submissions, and regulatory compliance documents all rely on postmarks for legal protection. The new system essentially shifts the burden of proof from the postal service to the sender.

Critical Implications for Tax Compliance

For taxpayers, this change creates significant risks:

• Tax return deadlines - A postmark dated after the filing deadline could trigger penalties, even if you mailed on time

• Estimated tax payments - Late postmarks could result in underpayment penalties

• Document submissions - IRS correspondence and appeals may be deemed untimely

• Charitable contributions - Year-end giving documentation could be compromised

Protective Measures You Should Take Now

To safeguard against potential deadline issues, the following steps are essential:

• Request hand-stamped postmarks - Ask postal clerks to manually postmark time-sensitive mail with the actual date of submission

• Purchase postage at the counter - Printed labels from counter transactions include the correct acceptance date

• Use certified or registered mail - These services provide definitive proof of mailing date

• Consider electronic filing - Where possible, electronic submission eliminates postmark uncertainty

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Questions?

Contact HFM CPAs for guidance on protecting your tax compliance and ensuring proper documentation of time-sensitive submissions. Our team can help you navigate these operational changes while maintaining full compliance with filing requirements.

HFM CPAs provides specialized accounting, tax, and assurance services to individuals and businesses across Connecticut and Rhode Island.