Is a PO Box a physical address?

A PO Box is a locked mailbox at a Post Office. Acceptance is the other party’s rule

Direct answer. usps.com describes a Post Office Box (PO Box) as “a locked mailbox within a Post Office facility.” That is a mailing address at the Post Office. This page does not treat that sentence as a general legal definition of “physical address.” Whether a given form, carrier, or card issuer accepts a PO Box is that party’s rule. Where Street Addressing is available, USPS says you may use the street address of the Post Office location together with the PO Box number as the mailing address. This page is not legal advice.

PO Box Blocker — AddressFence (Shopify App Store · Write a review). Free blocks PO Boxes and parcel lockers on the shipping address at checkout, plus a small set of ZIP rules. Street-number checks and billing-address rules are on a paid plan. It does not decide whether a carrier will deliver, or whether a card issuer will accept a billing address.

Related: B2B PO Guard — Require PO — B2B purchase order number required at company checkout.

Free check first: PO box and street number address checker runs in your browser and sends nothing. Paste an address and see which lines look like a PO Box.

Checklist before you call a PO Box a physical address

• Read the live usps.com PO Boxes page for what a PO Box is and for Street Addressing.
• Read Publication 28 § 284 before you write the Post Office street address with the box number.
• A commercial mail receiving agency is a different service. One line is below. The format is PMB and CMRA private mailbox addresses.
• For a commercial email footer, read item 4 of the FTC CAN-SPAM compliance guide. That sentence is about the email, not every form.
• For checkout, read Does Shopify ship to PO Boxes? and the billing-address block. Carriers state their own rules.

What USPS says a PO Box is

The usps.com page says: “Keep your personal or small business mail safe with a Post Office Box™ (PO Box™), a locked mailbox within a Post Office™ facility.” The same page, under Street Addressing, says:

With Street Addressing (if available), you have the option of using the street address of your Post Office location, combined with your PO Box number, as your mailing address. This lets you receive packages from private carriers (such as UPS, FedEx, DHL, and Amazon), as long as they comply with USPS mailing standards.

That street address is the Post Office location’s street address, combined with the box number. The page also says Street Addressing is subject to availability and restrictions, and it points to the Customer Agreement for more details. This page does not quote fees.

Publication 28 § 284 and a private mailbox

Publication 28 § 284, “PO Box Street Addressing,” says: “PO Box services in some locations allow for an option to use the Post Office street address for the mailing address, along with the PO Box number preceded by a ‘#’ sign or ‘UNIT’ designation.” How to write the line is US PO Box address format. This page does not repeat that format.

Section 285 is a different service: “Private companies offering mailbox rental services to individuals and businesses are considered commercial mail receiving agencies (CMRA).” The PMB format is PMB and CMRA private mailbox addresses.

One official use of “physical postal address”: a commercial email footer

Item 4 of the FTC’s CAN-SPAM Act compliance guide for business says:

Your message must include your valid physical postal address. This can be your current street address, a post office box you’ve registered with the U.S. Postal Service, or a private mailbox you’ve registered with a commercial mail receiving agency established under Postal Service regulations.

That sentence is the FTC’s rule for the footer of a commercial email covered by CAN-SPAM. It is not a general definition of a physical address for shipping, cards, or tax forms. This page does not quote a penalty amount.

Billing address, and what checkout can collect

The card issuer and the payment processor decide whether a PO Box is accepted as a billing address. This page did not find an official page to quote on that choice, so it does not say that a bank or a processor rejects or accepts PO Boxes.

Shopify checkout can collect a PO Box as the billing or shipping address. Whether a carrier then delivers is the carrier’s rule. Walk those two jobs on Does Shopify ship to PO Boxes? and block a PO Box on the billing address. Requiring the billing address to match shipping is a different control: billing match is not a PO Box block. Holding a PO Box ship-to that is billed to a commercial suite is a separate review path.

Carrier pages state their own rules. UPS is Does UPS deliver to a US PO Box? FedEx is Does FedEx deliver to a P.O. box? This page does not repeat those terms. Street Addressing, quoted above, is how USPS describes receiving packages from private carriers when that option is available and the carrier complies with USPS mailing standards.

What this page is not

• Not a dictionary definition, and not a claim that every law uses one meaning of “physical address.”
• Not a statement that a card issuer or a payment processor accepts or rejects a PO Box.
• Not the Publication 28 format page. That URL is US PO Box address format.
• Not the CMRA format. That URL is PMB and CMRA private mailbox addresses.

Related pages

• PO box and street number address checker — paste an address in the browser
• US PO Box address format — Publication 28 and Street Addressing
• PMB and CMRA private mailbox addresses
• Does Shopify ship to PO Boxes?
• PO box blocker
• PO box blocker for the billing address
• Billing match is not a PO Box block
• Does UPS deliver to a US PO Box?
• Does FedEx deliver to a P.O. box?
• Hold a PO Box ship-to billed to a commercial suite
• usps.com: Rent a PO Box
• Publication 28 § 284
• FTC: CAN-SPAM compliance guide
• PO Box Blocker — AddressFence — live App Store listing
• Shopify apps hub
• Tools

Not legal advice. Confirm the live usps.com PO Boxes page, Publication 28 §§ 284 and 285, and the FTC CAN-SPAM guide before you treat a PO Box as a physical address on a form. The app checks address rules you publish. It does not decide carrier eligibility or card acceptance.