Free Sample Form Says Address Not Recognized: How to Check Apartment Details

If a free sample form rejects your address, the cause is almost always a missing or oddly formatted apartment number — not a broken form and not a problem with your street. Most sample forms check what you type against USPS delivery data, and that check fails in two distinct ways: your building is known but the unit is missing, or the unit you typed does not match any unit on file. Knowing which of the two you hit changes what you do next.

One is fixed in about thirty seconds by retyping the line in the postal service's standard format; the other means the unit itself is not in the postal database yet, and no amount of retyping will help.

Verification note: Program terms and availability can change. This page was checked against linked sources on September 15, 2026.

The two error codes behind "address not recognized"

Sample forms usually validate through an address API, which returns a short code describing what went wrong. According to AccuZIP's reference for USPS Delivery Point Validation codes, footnote N1 means "high-rise address missing secondary number" — the building is real and deliverable, you just did not supply a unit. Footnote CC means you did supply one and it could not be matched to any unit on file.

The practical difference matters. GrayHair Software's explainer on CASS certification codes notes that a DPV result of "D" with N1 is a deliverable street address merely lacking a unit, while "N" with CC is a genuinely unrecognized address. A form built on the first case may accept your street with the apartment removed and still deliver to you; the second case is a real data gap.

You rarely see the raw code. What you see is a message asking for apartment, suite, or box information — which is the N1 case wearing a friendlier face.

Format the apartment line the way USPS expects

Most rejections are formatting, so start there. USPS Publication 28, section 213 requires a secondary unit designator — APT, STE, UNIT, RM, FL and similar — on addresses in multi-unit buildings, and says the pound sign should not be used when the correct designator is known or appears in the ZIP+4 file. If you do use #, a space must follow it.

Publication 28 also puts the designator and its number at the end of the delivery address line, or on its own line above the city, state and ZIP, and discourages non-standard forms such as "Apartment No." or "Suite #". Those are exactly the strings web forms fail to parse. A designator that is merely unusual, not wrong, is still a rejection.

"PH" is approved; "Penthouse" spelled out is not.

• Write `123 MAIN ST APT 4B`, not `123 Main St Apartment No. 4B`
• Put the unit at the end of the street line, or in the form's own Address Line 2 field
• Use `# 4B` with a space only when you do not know the proper designator
• Check your designator against Pub 28's approved list — Appendix C2 covers APT, BLDG, DEPT, FL, HNGR, KEY, LOT, LOWR, OFC, PH, PIER, RM, SIDE, SLIP, SPC, STOP, STE, TRLR, UNIT and UPPR
• Anything outside that list — "Flat", "Door", "Rear Apt" — is what a validator rejects

Look up the exact string the validator wants

You do not have to guess at the correct form. The USPS ZIP Code Lookup tool accepts a street address plus a unit and returns the standardized version with the ZIP+4. USPS guidance is to narrow a multiple-match result by adding your unit number.

That returned string is the closest free approximation of what a sponsor's validator is checking against. Copy the abbreviation, the spacing and the placement exactly as the lookup prints them, then paste that into the sample form. If the lookup returns your building but will not accept your unit, you have confirmed the CC case: the unit is not in the postal file.

If it returns your full address including the unit and the sample form still refuses it, the problem is the form's own parser, not your address.

When the unit genuinely is not on file

USPS does not assign addresses. Per the USPS FAQ on new construction and street address information, the local city, county or 911 addressing authority assigns them, and USPS then loads them into its Address Management System. A newly built building, or a house recently subdivided into units, can be unrecognized until that happens.

The same FAQ tells residents to report a missing address to their local Post Office or submit the online Growth Management Assistance Request, then re-check on usps.com after several business days. That is a real fix with a real wait attached — it will not rescue a sample offer closing this week. Newly converted rentals are the common case.

If a landlord split a single-family house into 1A and 1B last month, the parent address validates and neither unit does.

Why re-submitting the same form rarely works

Sample sponsors validate through APIs that standardize what you type. The USPS Web Tools Address Information API documentation shows the service converting input such as "Apartment" to "Apt" and returning a message asking for apartment, suite or box information when a high-rise address arrives without one. Because the check is deterministic, identical input produces an identical rejection.

Pressing submit again changes nothing — reformatting the line does. Two cautions. Some forms only pass Address Line 1 to the validator, so a unit typed into Line 2 may never reach the check; try moving it onto the street line.

And avoid dropping your unit entirely just to get past the form: an N1 address may still be delivered, but a sample landing at a building with no unit number is a delivery gamble, and most sample offers carry no replacement for a package that does not arrive.

Frequently Asked Questions

Should I use # or APT on a sample form?

Use APT when you know it. USPS Publication 28 says the pound sign should not be used when the correct designator is known or appears in the ZIP+4 file, and requires a space after # if you do use it.

Can I leave the apartment number off to get the form to submit?

Sometimes it will submit, because a DPV "D" result with footnote N1 is a deliverable street address merely lacking a unit. But delivery to a multi-unit building without a unit number is unreliable, and samples generally are not replaced.

How long does it take for a new unit to become recognized?

USPS does not state a fixed timeline. Its FAQ directs residents to report the address to the local Post Office or file a Growth Management Assistance Request, then re-check on usps.com after several business days.