Certificate of Mailing: what it is and when you need one

What is a Certificate of Mailing?

USPS's Domestic Mail Manual says Certificates of Mailing "may be presented only at the time of mailing and provide evidence that individual mailpieces have been presented to the USPS for mailing." The same section adds that they "do not provide a record of delivery, and the Postal Service does not retain copies of either form." In plain terms, the certificate is your own receipt, dated by USPS, for the day you mailed a letter, and it is up to you to keep it safe.

The form names the sender and the person you are writing to, with both addresses, and you can add an order or invoice number for your own reference. The clerk postmarks it with that day's date and hands it back.

How much does a Certificate of Mailing cost?

A Certificate of Mailing on PS Form 3817 costs $2.45 a letter on top of postage. For three or more letters, a firm sheet on PS Form 3665 costs $0.75 for each letter listed.

A 1 ounce letter with a Forever stamp and a PS Form 3817 comes to $3.27 in all. Fees are from USPS's Notice 123, in effect since October 4, 2026.

How do I get a Certificate of Mailing?

You fill in PS Form 3817, put full postage on the letter, and hand both to a clerk at a post office counter, who postmarks the form and gives it back to you.

1. Get a PS Form 3817 at the post office or print one from USPS's forms page.

2. Type it or fill it in with a ballpoint pen in ink, with your name and address and the name and address the letter is going to.

3. Put full postage on the letter, by stamp or any other way you normally pay.

4. Take the letter and the form to a post office counter and pay the fee. The clerk postmarks the form with the day's date and returns it to you.

5. Keep the form somewhere safe, because USPS has no copy to give you later.

For three or more letters at once, list them on a PS Form 3665 firm sheet instead, at $0.75 each. If you live on a rural route, the manual also lets you hand the letter, the form and the fee to your rural carrier, who has the form postmarked at the post office that day and brings it back on the next trip. You can't buy a certificate after the letter is in the mail, though you can get a duplicate of a PS Form 3817 later by bringing the original back to the counter.

When do you need a Certificate of Mailing?

Get one when a law, a court, an agency, a lease or a contract counts a deadline from the day you mailed something, and you want USPS's own record of that day. Notices to tenants and landlords, responses to an agency and payments with a postmark deadline are common examples.

A postmark doesn't always do that job, because in November 2025 USPS wrote that "the date inscribed by a postmark applied at a processing facility may be later than the date that the mailpiece was first accepted by the Postal Service." A letter dropped in a collection box late on the last day can be postmarked the next day. USPS's advice to anyone with a deadline is to mail earlier, to ask for "a manual (local) postmark at a retail location at no additional cost," or to buy a Certificate of Mailing, and the certificate is the one of those that leaves a receipt in your hands.

If you also need a record that the letter arrived, the certificate won't give you one. Certified Mail costs $5.55 on top of postage and gives you a mailing receipt plus a USPS record of delivery, and our guide to Certified Mail, a Certificate of Mailing or a tracked letter compares them side by side.

Is a USPS barcode scan proof of mailing?

No. A scan of a USPS Intelligent Mail barcode shows that USPS had the letter at a plant at a certain time, and USPS has said plainly that this is not a record of mailing. In its November 24, 2025 rule on postmarks, 90 FR 52883, USPS wrote that barcode scans "indicate possession of a mailpiece, but do not constitute evidence of the date when the Postal Service first accepted possession of a mailpiece," and that "they therefore are not adequate substitutes for a manual (local) postmark applied at retail or services such as Certificates of Mailing."

The reason is practical, since nobody scans a letter when you drop it in a collection box, so the first scan comes when a plant sorts it, often that evening and sometimes a day later. PigeonTrail shows those scans so you know where a letter is, and we never present them as a record of when you mailed it or of its delivery.

Can I use a Certificate of Mailing with a tracked letter?

Yes, and the two cover different needs. The certificate is USPS's record of the day you mailed the letter. The tracking shows you and the person you wrote to where the letter is along the way, the day USPS expects it, and the day USPS marks it delivered.

1. Print the envelope from PigeonTrail with the address and its USPS barcode, and put a Forever stamp on it.

2. Fill in a PS Form 3817 with the same names and addresses.

3. Hand the letter and the form to a clerk at the counter, pay the $2.45 fee, and keep the postmarked form.

4. Follow the scans in your PigeonTrail letters list until USPS marks the letter delivered.

On Pro, PigeonTrail can also print a one page mailing record for a letter, with the address check and every USPS scan. It helps you explain to a buyer what happened to a letter, while the certificate stays the record USPS stands behind for the mailing date.