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United States Postal Service updates postmark guidance: Impacts the IRS mailbox rule for timely tax submissions

ARTICLE | February 19, 2026 | By RSM US LLP

The new USPS reality: Postmarks no longer align with deposit dates

On Dec. 24, 2025, the USPS updated its Domestic Mail Manual (DMM 608.11) with language that postmarks ‘do not inherently or necessarily align with the date on which the Postal Service first accepted possession of the mail piece.’ The USPS acknowledges that ‘this lack of alignment has and will become more common’ as it continues implementing its network consolidation plan.

Critical implications for section 7502

The IRS mailbox rule (26 U.S.C. section 7502) treats a document as timely filed if postmarked on or before the due date. Courts interpret this strictly; the postmark date controls, regardless of when the taxpayer actually deposited the document. The Tax Court applies Reg. section 301.7502-1 with particular strictness. Under the regulation, if both a private meter date and a USPS postmark exist, the USPS postmark controls, even if it is later.

This change impacts numerous paper-filed returns, including Forms 706 (estate tax), 709 (gift tax), specialty Form 1120 filings (e.g., Interest Charge Domestic International Sales Corporation (IC-DISC), U.S. Property and Casualty Insurance Company (PC) and Regulated Investment Company (RIC), etc.), certain international forms like Form 3520, all of which are paper-filed. State filings may also require paper filing.

USPS-approved solutions for taxpayers

The USPS has identified three methods that provide proof of timely mailing aligned with the actual deposit date:

Buy postage directly from the USPS worker at the counter. The Postage Validation Imprint (PVI) label shows the actual date of acceptance. This provides contemporaneous evidence but requires an in-person visit during business hours. This is different from using a self-service kiosk, which does not provide a postmark and only demonstrates the date the postage was purchased.

Request a manual postmark. Customers can request a manual postmark at no extra charge at any Post Office. Since it is stamped upon acceptance at the retail counter, the date aligns with the actual deposit.

Purchase a Certificate of Mailing. This provides official evidence of the date the USPS accepted possession. Certified mail and registered mail also provide mailing receipts with acceptance dates.

Critically, pre-printed labels from Self-Service Kiosks, Click-N-Ship or postage meters only prove postage purchase, not USPS acceptance. This includes certified mail stickers obtained from self-service kiosks. Without an official USPS acceptance stamp, these items cannot serve as proof of mailing date for deadline-sensitive filings.

Tax practitioners and taxpayers should be aware of these USPS changes when planning their filing strategies for paper returns.

Please connect with your advisor if you have any questions about this article.