The question shows up as a checkbox on carrier accounts, checkout pages and government forms, and it looks like it should take one second to answer. Then you look at the address you actually use, which reads something like 10 Main St PMB 234, or 131 S Center St # 3094, and the checkbox stops being obvious.
That hesitation is reasonable. The Postal Service recognizes three kinds of box-style address, and the form is only asking about one of them. Two of the three carry a street name, one of those two is still a post office box underneath, and the other one is a private mailbox that USPS rules say may never be called a PO Box on the envelope.
This article sorts the three by the rules USPS publishes for its own addressing, tells you what each one means for the checkbox, and ends with the format rules for a PMB address, because getting the second line wrong is the fastest way to lose mail at a private mailbox.
Three addresses the form treats as one question
USPS Publication 28 is the addressing standard that postal software is built on, and it gives each of the three its own section. The table below is the short version.
| What your address looks like | What it is | Who delivers there | Is it a PO Box? |
|---|---|---|---|
| PO BOX 3094, Collierville TN 38027 | A post office box, rented from USPS inside a Post Office | USPS only | Yes |
| 131 S Center St # 3094, Collierville TN 38027 | The same post office box, written in the Post Office's street-style format (Post Office Box Street Address, or PBSA) | USPS to the box; private carriers can deliver packages to the Post Office | Yes to USPS, and the guide calls it an equivalent of the traditional format |
| 10 Main St PMB 234, Herndon VA 22071 | A private mailbox at a commercial mail receiving agency (CMRA), a company at a street address | USPS and private carriers, to the company's front counter | No. The PO BOX label is prohibited on this address line |
The first row is the plain case. Publication 28 section 281 says a post office box address "must be standardized as follows: PO BOX ##", and there's nothing else on the delivery line. If your address reads that way, the checkbox is yes and you can stop reading.
The second and third rows are where the confusion lives, and each one has a section of Publication 28 behind it.
The street-addressed box is still a post office box
Section 284 describes an option USPS offers alongside some PO Boxes: "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."
The address that option produces is the Post Office's own building. USPS's guide to the program walks through an example for ZIP Code 38027, where the Post Office sits at 131 S Center St. A customer renting box 3094 there who signs up for the option would write the address as 131 S Center St # 3094, Collierville TN 38027. The guide's own description of the arrangement is the sentence that answers the checkbox: the option lets a customer use the street-style form "as an equivalent of the customer's traditional P.O. Box-style address."
Equivalent is the operative word. The same box receives the mail under either spelling. USPS's page for the service says customers "should not submit a Change of Address (COA) from their PO Box to the associated street-style address because both addresses will be delivered to their PO Box." Nothing physical changed; what changed is the spelling on the envelope.
That's the honest use of the option, and USPS says so directly: "Some merchants do not allow shipping to a PO Box address. The Street Addressing option enables customers to order online and receive package deliveries from private carriers who require a street address for delivery, such as UPS, FedEx, DHL, or Amazon." If the form is a shipping form, the street-style box does what you need. If the form is asking whether you have a post office box, the truthful answer is still yes.
The guide also sets limits worth knowing before you count on the option. It "is not available to caller service customers, alphanumeric P.O. Box numbers, or P.O. Box customers who receive boxes for no fee", and a box number that collides with an existing unit in the building is excluded from street addressing.
We covered the other half of this arrangement, how a street-addressed box holds up on a business form and at a bank, in Can You Use a PO Box as a Business Address?. This article stays on the postal side of the line.
A PMB is a private mailbox, and USPS forbids calling it a PO Box
Section 285 covers the third case. "Private companies offering mailbox rental services to individuals and businesses are considered commercial mail receiving agencies (CMRA)." Mail to a customer there "must include either the PMB identifier or the #, followed by the appropriate private mailbox number. Use of any other identifier is prohibited."
Then comes the sentence that settles the checkbox for this kind of address: "The words POST OFFICE BOX or PO BOX and the private mailbox number cannot be used on the Delivery Address Line. Only the Postal Service is entitled to provide delivery to a PO Box."
So a PMB address isn't a post office box in the postal sense. It's a numbered box inside a private company's premises, at that company's street address, and the carrier hands the mail to the company. The Domestic Mail Manual adds the paperwork behind the arrangement: "The CMRA must ensure that all its addressees (customers) have a current PS Form 1583 on file", and that form is what lets the company accept your mail in the first place. If that form gives you trouble, we wrote up the six documents USPS accepts as proof of address on Form 1583.
The checkbox answer for a PMB is no. The reason you may still see the address treated as a box somewhere is the next section.
How a form can know before you answer
Address validation software doesn't read the checkbox. It reads USPS reference data, and USPS publishes that data with the box-style addresses marked.
The PBSA guide lists the tools a mailer can use to spot a street-addressed box. Two of them matter here. First, all of those addresses sit on their own carrier routes: "Carrier route numbers C770 through C779 indicate PBSA addresses." Second, and this is the one that catches private mailboxes too, USPS maintains a table for CMRA addresses and puts the street-addressed boxes in it as well: "ALL PBSA addresses are included within the DPV CMRA table that identifies addresses that are associated with either a Commercial Mail Receiving Agency or a PBSA. When a match of an input address is made to the data in the DPV CMRA table, the user can determine that the input address represents a CMRA or PBSA delivery location."
That single table explains most of the surprises people report. A checkout page that runs your address through validation gets a flag back saying the address is a CMRA or a street-addressed box. What the page does with the flag is up to the merchant, the bank, or the agency. One merchant treats any flagged address as a box and refuses it, while another accepts a CMRA and refuses only the box, and plenty of forms never read the flag at all.
The practical reading: answer the checkbox truthfully according to the table above, and understand that the other side may already have classified your address on its own. For a bank, the rule it's applying is a federal one about the address it collects at account opening, and we traced it in Can You Open a US Business Bank Account Without a Physical Address?. For a form that asks about a mailing address versus a business address, the terms mean different things and we separated them in Business Mailing Address vs. Business Address.
How to write a PMB address so the mail keeps arriving
The form is one problem. The envelope is the other, and the envelope has stricter rules. The Domestic Mail Manual, section 508.1.8.3, is where the format lives, and it starts with the identifier: "A CMRA must represent its delivery address designation for the intended addressees by the use of "PMB" (private mailbox) or the alternative "#" sign."
Two layouts are allowed. In the four-line version the box gets its own line, above the street: "Line 2: "PMB" and number or the alternative "#" (pound sign) and number. Examples: PMB 234 or #234." In the three-line version the box is appended to the delivery line, as in "10 MAIN ST PMB 234" or "PO BOX 34 PMB 234".
| Situation | Write it as | Why |
|---|---|---|
| Mail center is at a plain street address | JOE DOE / PMB 234 / 10 MAIN ST / HERNDON VA 22071-2716 | Four-line format from DMM 508.1.8.3, box above the street |
| Same, on a form with two address lines | Line 1: 10 Main St, Line 2: PMB 234 | Most forms print line 2 under or after line 1, which lands you in the three-line layout; the box still carries its own identifier |
| Mail center itself has a suite number, written on one line | JOE DOE / 10 MAIN ST STE 11 PMB 234 / HERNDON VA 22071-2716 | Three-line layout with a suite: DMM requires the word "PMB" here, and the two numbers stay apart |
| Same building, four-line layout | JOE DOE / PMB 234 / 10 MAIN ST STE 11 / HERNDON VA 22071-2716 | Box above the street; the DMM's own four-line example lists "10 MAIN ST STE 11" as the street line and allows PMB or # above it |
| The two numbers merged, like 10 MAIN ST STE 11-234 | Don't | DMM says it "is not permissible to combine" the building's secondary element with your box number |
The suite case deserves its own paragraph, because it's the one that trips up people whose mail center is in an office building. The DMM makes it an explicit exception: "when the CMRA's physical address contains a secondary address element (e.g., rural route box number, "suite," "#," or other term), the CMRA customer must use "PMB" in the three-line format. It is not permissible to combine the secondary address element of the physical location of the CMRA address and the CMRA customer private mailbox number, e.g., 10 MAIN ST STE 11-234."
Read the scope of that exception carefully. It bites when the box and the suite share a line. The four-line layout, with the box on the line above the street, still accepts either identifier, and the DMM's four-line example lists "10 MAIN ST STE 11" among its street lines with "PMB 234 or #234" above it. Once you collapse the address to one line, the word PMB is required and the suite number and the box number are written as two separate elements.
The penalty for leaving the identifier off is spelled out too. "The USPS may return mail without a proper address to the sender endorsed 'Undeliverable as Addressed, Missing PMB or # Sign.'" A sender who copies your address from an email signature and drops the PMB line can lose the letter to that endorsement, so it's worth writing the box on its own line wherever you publish the address.
One more rule from Publication 28 section 213 explains why "#" and "PMB" aren't fully interchangeable. In ordinary addressing, "the pound sign (#) should not be used as a secondary unit designator if the correct designation, such as APT or STE, is known or is shown in the ZIP+4 file", and the section carries a note aimed at exactly this situation: "Use of the pound sign might be prohibited when using a Commercial Mail Receiving Agency (CMRA) address with Private Mail Box (PMB) information." When in doubt, PMB is the safer of the two.
If your box is in Canada, the same question runs the other way, because there the PMB designation carries different baggage and the unit-number format is the safe one. We covered that side in Canada Post Address Format: Unit/# vs PMB vs PO Box. The two articles disagree on purpose, because the two postal systems do.
Where a virtual mailbox address sits in all this
A virtual mailbox is the third row of the first table. The company is a CMRA, your box has a PMB or # number, and the address is the company's street address in a real building. When a form asks whether your mailing address is a PO Box, the answer for that address is no, and the format section above is the format you'll use.
Our Virtual Mailing Address and Virtual Business Address plans are built the same way. Your address will be a real commercial street address in one of the US cities we're opening, with a PMB or # number for your box. You see a photo of every envelope as it arrives, and opening and scanning is $1.99 a piece, only when you ask. Whether a given bank or platform accepts a CMRA address is that institution's call, and we'd rather you check its rule than take a sales page's word for it. If a street address with a numbered box is what your forms need, you can get your address and have the exact format to paste before the first letter arrives.
FAQ
What does "Is your mailing address a PO Box?" mean on a form?
The form is asking whether the address it will mail or ship to is a box inside a USPS Post Office rather than a street location. Merchants and carriers ask because, in USPS's own words, "some merchants do not allow shipping to a PO Box address" and private carriers "require a street address for delivery." Banks and agencies ask for their own reasons, usually a rule that wants a location tied to you. Answer yes for PO BOX and for the street-addressed version of a USPS box, and no for a PMB at a private mail center.
Is a PMB considered a PO Box?
No, in postal terms. Publication 28 section 285 says the words "POST OFFICE BOX or PO BOX and the private mailbox number cannot be used on the Delivery Address Line" and that "only the Postal Service is entitled to provide delivery to a PO Box." A PMB is a private mailbox at a commercial mail receiving agency. Some validation systems will still flag it, because USPS lists CMRA addresses in its DPV CMRA table, and each merchant decides what to do with that flag.
Is my PO Box the same as my address if I use the street-addressed option?
Yes. USPS describes the street-style form as "an equivalent of the customer's traditional P.O. Box-style address", and mail sent to either spelling lands in the same box. That's also why USPS tells customers not to file a change of address between the two formats. The street-style version exists so packages from private carriers can reach the Post Office, and it doesn't turn the box into a street location for any other purpose.
Is my shipping address a PO Box if the carrier won't deliver to it?
If the address reads PO BOX, private carriers generally can't deliver to it, because the box is inside a Post Office. The street-addressed option is USPS's answer to that, letting the carrier bring the package to the Post Office's street address. A PMB at a private mail center is a street address for carrier purposes, and the company signs for packages at its counter.
Should the PO Box or PMB go on address line 1 or line 2?
On a two-line form, keep the box on the second line: line 1 for the street address of the mail center, line 2 for "PMB 234" or "# 234". The form will usually print that as one street line followed by the box, which is the three-line layout DMM 508.1.8.3 allows. If the mail center's address already has a suite number, keep the suite with the street on line 1 and write "PMB 234" on line 2, spelled out as PMB rather than #, because a suite and a box on one line is the case where the DMM requires the word. Never merge the two numbers into something like STE 11-234.
How can I tell if an address is a PMB?
Read the delivery line. "PMB" followed by a number, or "#" followed by a number at a private company's street address, is a private mailbox. When that same "#" and number sit at a Post Office's street address, you're looking at a street-addressed USPS box, and "PO BOX" followed by a number is the plain kind. If you're checking an address you didn't write, USPS's guide says the DPV CMRA table and carrier routes C770 through C779 are how software identifies the two street-style cases.
Bottom line
USPS has three box-style addresses and one checkbox to describe them. The PO BOX line and its street-addressed twin are both post office boxes, and you answer yes for either. A PMB at a commercial mail receiving agency is a private mailbox at a street address, the PO BOX label is prohibited on it, and you answer no.
Whatever you answer, the other side may already have looked your address up in the same USPS tables described here, so the useful move is to know which of the three you have and write it the way the Domestic Mail Manual asks. For a PMB, that means the box on its own line where the form allows it, the word "PMB" rather than "#" whenever the box shares a line with the building's suite number, and the two numbers never combined.
This is general information about USPS addressing standards rather than legal or banking advice. Each merchant, carrier, bank, and agency applies its own address policy, and USPS publications are revised over time, so check the current edition and the institution's own rule for your situation.
