You can use a P.O. Box on Form W-9, but only when the U.S. Postal Service does not deliver mail to your physical street address. In every other situation, line 5 of the form expects a street address. The address you enter tells the payer where to send your 1099 and other year-end tax documents, so what goes on that line has practical consequences beyond the form itself.
When the P.O. Box Exception Applies
Line 5 of Form W-9 asks for your address as a number, street, and apartment or suite number.1Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification A P.O. Box is acceptable in place of that street address only when the Postal Service does not deliver to your physical location. This typically covers people in rural areas, on tribal lands, or in other locations without home mail delivery.
If you have both a street address that receives mail and a P.O. Box, use the street address. The IRS prioritizes a physical location because it links you to a real geographic address for tax compliance purposes. Payers who receive a W-9 listing a P.O. Box should accept it when the filer confirms that regular mail delivery is unavailable at their home or office.2Internal Revenue Service. Instructions for the Requester of Form W-9
Filling In Lines 5 and 6
Your address is split across two lines on the form:
- Line 5 takes the street address, or a P.O. Box if the no-delivery exception applies.
- Line 6 takes the city, state, and ZIP code that go with line 5.
Keep the two lines consistent. The city, state, and ZIP on line 6 should match wherever you’re routing mail on line 5.
Updating a W-9 After You Move
If your address has changed since you last gave the payer a W-9, submit a new form and write “NEW” at the top of line 5.1Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification That flag tells the payer to overwrite the address they have on file rather than treat the form as a duplicate.
The payer may keep using your old address until they update their records, so it’s worth following up to confirm the change went through. The IRS doesn’t set a deadline for notifying payers about an address change, but the sooner you update it, the more likely your 1099 lands in the right mailbox at year-end.
A simple move from a street address to a P.O. Box after relocating to an area without home delivery is handled the same way: new W-9, “NEW” at the top of line 5, P.O. Box on the line.
Why the Address Is Not What Triggers Withholding
An address problem on Form W-9 can cost you a tax document in the mail. It doesn’t cost you a percentage of your payments. Backup withholding, which requires the payer to hold back 24 percent of what they pay you and send it to the IRS, is triggered by problems with your taxpayer identification number, not your address.3Internal Revenue Service. Backup Withholding
The name on line 1 and the TIN you enter must match IRS records. If they don’t, the payer may receive a CP2100 notice about the mismatch, which can lead to backup withholding on your future payments.4Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice Enter your name as it appears on your federal tax return, and pair it with the SSN, EIN, or ITIN that goes with that name.1Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification Getting the P.O. Box question right doesn’t help you if the name and TIN don’t line up.
Sending the Completed Form
Return the completed W-9 to the business or person who requested it. Do not send it to the IRS; the agency doesn’t collect these forms.5Internal Revenue Service. About Form W-9, Request for Taxpayer Identification Number and Certification The requester keeps it in their records and uses the information to prepare your 1099.
Because the form carries your SSN or EIN, protect it in transit. Encrypted email, a password-protected document portal, or an in-person handoff are all safer than plain email. If you mail a paper copy, certified mail with a return receipt lets you confirm delivery.
Many payers run the name and TIN on your W-9 through the IRS TIN Matching program before filing information returns.6Internal Revenue Service. Taxpayer Identification Number (TIN) Matching If they find a mismatch, expect a request for a corrected form before year-end.