Certified Mail
The everyday option for individual returns, elections, protest letters and Tax Court petitions. The sender's receipt, dated at the window, is the proof of mailing; adding Return Receipt gives the delivery signature back.
Tax filings
What the IRS accepts as proof of delivery
Two USPS services and a short list of private carrier tiers. That is the whole answer. Under 26 CFR 301.7502-1, a properly postmarked Certified Mail sender's receipt, a properly registered Registered Mail receipt or a receipt from an IRS-designated Private Delivery Service are each prima facie evidence that a return, election or payment was timely delivered. Nothing else — not a plain tracking number, not a fax confirmation, not a certified email — qualifies for that.
Regulation quotedPDS list explainedWhat to keep
Two receipts, one rule
The postmarked sender's receipt is what the Tax Court reads, not the letter's arrival.
The three qualifying paths
Section 7502 recognizes a mailbox rule. Its regulation, 26 CFR 301.7502-1, extends that rule to a small set of carrier services. Anything outside the list still has to prove actual arrival by the deadline.
| Service | What counts as the postmark | What the payer keeps |
|---|---|---|
| USPS Certified Mail | The date stamped on the sender's receipt at the counter | PS Form 3800 sender's receipt with the round-dater; return receipt (PS Form 3811) after delivery if requested |
| USPS Registered Mail | The date the item was registered by the Postal Service | The registration receipt with the manuscript entry number; return receipt if requested |
| Designated Private Delivery Service | The date the carrier records as the shipping date on the receipt or in the tracking record, treated as the postmark | The shipping receipt with the recorded ship date and, if available, the delivery record |
The regulation states, in plain terms: “proof that the document was properly registered or that a postmarked certified mail sender's receipt was properly issued and that the envelope was properly addressed” is prima facie evidence of delivery. That is why filers keep the little sender's receipt from the post office counter next to the return itself.
Which carrier tiers are on the PDS list
Only the services the IRS names in Notice 2016-30, as updated. The current list — publicly posted on irs.gov — covers certain FedEx tiers (FedEx First Overnight, Priority Overnight, Standard Overnight, 2Day, International Next Flight Out, International Priority, International First and International Economy), certain UPS tiers (UPS Next Day Air Early A.M., Next Day Air, Next Day Air Saver, 2nd Day Air, 2nd Day Air A.M., Worldwide Express Plus, Worldwide Express) and DHL Express Worldwide, DHL Express Envelope, DHL Import Express Worldwide, DHL Import Express Envelope and DHL Import Express 12:00.
Services outside the list — FedEx Ground, FedEx Home Delivery, UPS Ground, UPS 3 Day Select and every economy or standard tier — do not qualify under the mailbox rule. A return sent on one of those services and lost in transit is not treated as timely, regardless of the ship date on the receipt.
Which USPS product to buy at the counter
Registered Mail
For irreplaceable documents or high-value payments. The item is signed for at every carrier transfer, and the registered receipt bears a unique number. Slower, more expensive; the proof of both mailing and delivery is stronger.
Return Receipt Electronic
Cheaper than the paper green card and delivers a PDF signature image. It is the delivery confirmation; the mailing proof is still the sender's receipt for Certified or Registered.
Every filer's habit: keep the sender's receipt clipped to a copy of the addressed envelope and the return itself for at least three years — the general statute of limitations for a return — and longer for fraud-adjacent items.
Ship a tax envelope through SMKlog
The shipping calculator can price a USPS envelope on Priority or Ground Advantage, but Certified Mail and Registered Mail are Postal Service window products that a filer typically purchases at the counter or through a Post Office lobby retail unit. For a private-carrier tender, the calculator prices FedEx Priority Overnight and 2Day and the equivalent UPS tiers that appear on the IRS Notice 2016-30 list.
Where these rules come from
- Legal Information Institute, 26 CFR Sec. 301.7502-1 — Timely mailing of documents and payments treated as timely filing and paying — the mailbox rule, the postmark provisions and the prima facie evidence language for Certified and Registered Mail. Read 2026-08-11.
- Internal Revenue Service, Notice 2016-30 — the Designated Private Delivery Services list, updated by later notices, that names the qualifying FedEx, UPS and DHL Express tiers. Referenced via irs.gov, 2026-08-11.
- Federal Register, Timely Mailing Treated as Timely Filing — the 2011 rulemaking history that added the PDS mechanic to the regulation. Read 2026-08-11.
The IRS updates the PDS list without amending the underlying regulation. Confirm the current list on irs.gov before assuming a specific overnight tier still qualifies.
Common questions
What is the IRS timely-mailing rule?
Under IRC Sec. 7502 and the regulations at 26 CFR 301.7502-1, a document mailed on or before a filing deadline is treated as filed on the postmark date, provided it eventually arrives. That protects a filer whose envelope lands at the IRS after the due date but was postmarked by it.
What is prima facie evidence of delivery under the rule?
The regulation names two receipts: a properly registered mail receipt and a properly postmarked certified mail sender's receipt. Either one, together with proof that the envelope was properly addressed, is treated as prima facie evidence that the document was delivered to the IRS.
Does a private delivery service like FedEx or UPS count?
Only when the specific service is on the IRS-designated Private Delivery Services list. The IRS updates the list periodically; the current version is in the most recent Notice 2016-30 as amended and is publicly posted on irs.gov. A service that is not on the list — including many economy tiers of otherwise designated carriers — does not qualify.
Is a plain Ground Advantage receipt with tracking enough?
No. The regulation is explicit that only Registered Mail or Certified Mail — not tracking alone — creates prima facie evidence of delivery for filing-deadline purposes. Tracking may prove delivery in fact, but it does not satisfy the mailbox rule under section 7502.
What do I keep after mailing?
The dated sender's receipt for Certified or Registered Mail, the return receipt (PS Form 3811) once it comes back, and a copy of the addressed envelope. For a PDS shipment, the shipping receipt with the postmark-equivalent date and the delivery confirmation. Save them until the statute of limitations for the return runs, typically three years.