A change in U.S. Postal Service postmarking procedures is expected to affect time-sensitive tax filings and payments for 2026.
As a result, Maine Revenue Services is encouraging taxpayers to submit electronically or to use mail options with verified postmark dates.
Under the new USPS procedures, the postmark will still show the date of the first automated processing operation, but may no longer reflect the date when the mailing was physically deposited at a post office.
MRS is reminding taxpayers that filing state returns and payments through the Maine Tax Portal is the most reliable method to ensure filings are received on a timely basis.
Taxpayers who prefer to file by mail should request a USPS official to handstamp a postmark with the actual mailing date. In-person mailing by certified or registered mail are other options at USPS retail locations that also provide proof of mailing dates.
The USPS postmark procedures will affect all time-sensitive mailings, including, but not limited to, state tax returns and payments, petitions for reconsideration to the Maine Revenue Service, and petitions to the Maine Board of Tax Appeals or to Maine courts.