The rule in one sentence
The Domestic Mail Manual describes the form directly:
“Certificates of Mailing provide evidence that individual mailpieces have been presented to the USPS for mailing. Certificates of Mailing do not provide a record of delivery, and the Postal Service does not retain copies of either form.”
DMM 503.5, pe.usps.com, read 2026-08-11
Two practical points. The certificate proves acceptance on the postmark date, and only that. And because USPS keeps no copy, the postmarked slip in your possession is the record - lose it and the proof is gone.
Buying one at the counter
Fill out the form
PS Form 3817 is a small slip a clerk hands over on request. Write the sender, recipient and the mail class, and hand it back with the piece being mailed.
Pay the fee and take the receipt
$2.45 per article, per USPS Notice 123 effective 2026-07-12 and read 2026-08-11. The clerk applies a round-dater postmark to the form and returns it. That postmarked slip is your evidence.
Bulk certificates
For a batch, PS Form 3877 lists many pieces on one form and takes a firm-mailing bill discount. Available to any mailer with three or more pieces at once. USPS Notice 123 lists a lower per-piece fee for the firm certificate.
When Form 3817 is the right tool
Certificate of Mailing exists for one job: proving a deadline was met by depositing the piece with USPS on time. It sits below Certified Mail in cost, and below Registered Mail in security, because it is doing less.
| Question | Certificate of Mailing | Certified Mail |
|---|---|---|
| Proof piece was accepted | Yes, on the postmark date | Yes, and it produces a barcode |
| Delivery scanned | No | Yes, and events post on tools.usps.com |
| Signature captured | No | Yes when combined with Return Receipt |
| USPS keeps a copy | No | Yes, delivery record retained for two years |
| Current fee | $2.45 | Higher - see Notice 123 |
A tax return or a legal document filed by mail on the last day of a filing window is the textbook use. The postmark on Form 3817 is enough to satisfy an on-time filing dispute later. When the recipient can also lose the letter, upgrade to Certified with Return Receipt.
Where a sender can slip up
The receipt is the evidence, not the mailing. A postmarked 3817 that has been thrown away in a filing cull has no back-up copy at any post office. Scan it and store the image the same day. A drop-in-the-blue-box mailing cannot use a Certificate of Mailing - the counter must postmark the slip, so the trip to the counter is the point.
Sources
- USPS, DMM 503 Extra Services - Certificate of Mailing definition and rules (503.5). Read 2026-08-11.
- USPS, Notice 123 Price List - PS Form 3817 fee of $2.45, effective 2026-07-12. Read 2026-08-11.
Common questions
What is PS Form 3817?
A Certificate of Mailing - a small USPS receipt postmarked at the counter to prove a specific mailpiece was accepted on a specific date. It does not track the piece.
How much does a Certificate of Mailing cost?
$2.45 per article at the counter, per USPS Notice 123 effective 2026-07-12.
Does USPS keep a copy of my 3817?
No. The DMM says the Postal Service does not retain a copy. The postmarked slip in your possession is the only record.
When should I use it instead of Certified Mail?
When you only need proof the piece was mailed on time and do not need delivery tracking or a signature. It is much cheaper than Certified.
Can I get a Certificate of Mailing on a package dropped in the blue box?
No. The postmark must be applied by a clerk, so the piece has to be presented at the counter.