Postmark vs Postage: What Is the Difference?

People use "postmark" and "postage" interchangeably, but they refer to completely different things. Mixing them up is harmless in casual conversation — until you need to prove when a letter was mailed. Then the distinction can cost you money.

Postage is what you pay — postmark is what USPS stamps on it#

Postage is the fee you pay for USPS to deliver your mail. You can pay with a Forever stamp, a metered impression, or a label printed from an online service. The form factor varies, but the function is the same: postage is proof of payment.

A postmark is a mark that USPS applies to your mail during processing. The round-date postmark — the circular stamp you see over or near the stamp — shows the date the piece was processed and the facility that handled it. You do not pay for a postmark. USPS applies it as part of normal mail processing.

Think of it this way: postage gets your letter into the system. The postmark records when USPS accepted it.

One important detail changed in late 2025. USPS updated its processing procedures so that the postmark date now reflects when the piece hits "first automated processing" — not necessarily the day you dropped it off. If you put a letter in a blue collection box on Monday evening, it might not be postmarked until Tuesday or Wednesday. For more on what this means and how to control it, see our guide to postmarking a letter.

Does every letter get postmarked?#

No. Several common mail types skip postmarking entirely:

• Metered mail. If you use a Pitney Bowes or similar postage meter, the meter impression replaces the stamp — and USPS typically does not postmark over it.
• Online postage labels. Services like Stamps.com and Pitneyship print a barcode label that serves as both postage and tracking. No round-date postmark is added.
• Presorted bulk mail. Commercial mailers that presort by ZIP code often bypass the cancellation equipment that applies postmarks.
• EDDM (Every Door Direct Mail). EDDM pieces are dropped directly at the destination delivery unit and do not receive postmarks.

If your letter has a Forever stamp or other adhesive postage, it will almost always receive a postmark during automated processing. But "almost always" is not the same as "guaranteed" — especially for letters that are hand-sorted at smaller facilities.

Why the difference matters for deadlines#

When a deadline says "must be postmarked by" a certain date, the date on your postage does not count. Only the USPS postmark date matters.

This distinction is critical for:

• IRS tax filings. Under the "timely mailing is timely filing" rule (26 USC § 7502), the IRS accepts a return as on time if it is postmarked by the due date. A meter date or label date does not qualify. See our IRS mailbox rule breakdown for the full details.
• Legal notices. Lease terminations, contract cancellations, and court filings often require proof of mailing by a specific date. A postmark provides that proof; a postage date does not.
• Insurance claims. Many insurers require claims to be mailed by a deadline. The postmark date determines compliance.

If you are mailing something deadline-sensitive and want certainty, you have two options: request a free manual postmark at any Post Office counter, or use Certified Mail which provides an independent receipt with a dated acceptance stamp.

Quick reference table#

Here is how postage and postmarks compare across the dimensions that matter most:

The key takeaway: if you need to prove when something was mailed, you need a postmark or a proof-of-mailing service — not just postage. For a deeper comparison of postmarks, Certificates of Mailing, and Certified Mail, see our postmark vs proof of mailing guide.