USPS Clarifies Postmarking Procedures Impacting Timely Filing & Payment of Taxes

Article | January 27, 2026

by Horty & Horty, P.A.

On August 12, 2025, the Postal Service published a proposed rule in the Federal Register, Postmarks and Postal Possession, 90 FR 38716 (Aug. 11, 2025) (hereafter “the Proposed Rule”). The Proposed Rule defined the postmark and explained the Postal Service’s operational use of the postmark; identified the types of Postal Service markings that qualify as postmarks (together with certain auxiliary markings and scan data that are generated during the course of postal operations and that indicate postal possession of a mail piece but do not qualify as postmarks); described how and where in the course of postal operations such markings are applied; and clarified the scope of information that such markings do and do not convey.

The Proposed Rule further advised that, while the presence of a postmark on a mail piece confirms that the Postal Service was in possession of the mail piece on the date of the postmark’s inscription, the postmark date does not inherently or necessarily align with the date on which the Postal Service first accepted possession of the mail piece. The Proposed Rule further noted that this lack of alignment has and will become more common with the implementation of the Regional Transportation Optimization (RTO) initiative and the corresponding adoption of “leg”-based service standards. (90 FR 10857). The Proposed Rule then advised customers to request a manual (local) postmark at a retail location if they want to ensure that their mail piece receives a postmark containing a date that aligns with the date on which the Postal Service first accepted possession of their mail piece, and reminded customers who wish to retain proof of the date on which the Postal Service first accepted possession of their mail piece(s) of the services (including Certificates of Mailing) that provide such proof. Finally, the Proposed Rule submitted a new Section 608.11 of the Domestic Mail Manual (DMM), for the public’s consideration.

While the Postal Service has chosen to utilize the notice-and-comment rulemaking process for this Proposed Rule, we note that this is not a rulemaking in the traditional sense. As stated in the Proposed Rule, nothing in DMM Section 608.11 effectuates any changes in how, or the extent to which, the Postal Service applies postmarks to mail pieces. However, the postmark was not previously defined in any current Postal Service regulations, and the Postal Service considered it appropriate to reflect these existing practices in the DMM to ensure that customers have a clear understanding of the postmark and what it means.

The Proposed Rule sought public input on DMM Section 608.11, welcoming the perspectives of customers, government entities, industry stakeholders, and other interested parties. In particular, the Proposed Rule solicited recommendations on how to effectively inform customers of the new DMM provision and explain its meaning and feasible suggestions to advise and accommodate customers who want proof of the date on which the Postal Service first accepted possession of their mailings.

If you plan to submit tax return filings and/or tax payments via U.S. mail, you must be able to prove timely mailing/filing.  Merely dropping your mail pieces off at the post office or in a mailbox are no longer sufficient means of ensuring that a postmark will be applied on the same date.  When mailing time-sensitive tax filings or tax payments, at minimum, you should request a manual postmark at a retail location to ensure the postmark aligns with the date of mailing.  However, we recommend that you use certified mail with return receipt requested in order to substantiate timely filing of your tax returns and payments.