Does the IRS Accept a P.O. Box Address for Business?

The IRS accepts a P.O. Box as a business address on most federal tax returns, but only when the U.S. Postal Service doesn’t deliver mail to your street address. If USPS delivers to your street, that street address is what belongs on the form. Schedule C is stricter still, and the EIN application treats mailing address and physical location as two separate questions with different rules. Getting the distinction right matters because the IRS sends legally binding notices to the address on file, and the deadlines on those notices run whether you see them or not.

What Each Business Form Requires

Most annual business returns give you a single address block, not a split between “mailing” and “physical.” What can go in that block depends on the form.

Form 1120 asks for the corporation’s “principal office or place of business.”¹ Form 1065 asks for the partnership’s address in a similar single block.² Both allow a P.O. Box, but only if the postal service does not deliver to your street address. In that situation, the instructions say to show the P.O. Box number “instead” of the street address. The word “instead” matters: you replace the street address, you don’t add the box to it. Rural businesses and companies in areas without street delivery are the usual case. Preference or privacy is not a valid reason to substitute a box for a street address that USPS does deliver to.

Schedule C is tighter. The Line E instructions tell sole proprietors to enter the business address and “show a street address instead of a box number.”³ If you run the business from the home already listed on page one of your 1040, you can leave Line E blank.

Form SS-4, the EIN application, is the one form that clearly splits the two. Lines 4a–4b are for the mailing address, and a P.O. Box is fine there. Lines 5a–5b are for the entity’s physical street address if it differs from the mailing address, and the instructions explicitly say: “Don’t enter a P.O. box number here.”⁴ Line 6 then asks for the county and state of the physical location, which the IRS uses to determine which service center handles the account.

Home Addresses and Commercial Mailbox Services

A home address is acceptable as your business’s physical location if you actually work from that residence. Many sole proprietors, single-member LLCs, and small partnerships operate this way, and the IRS treats the home address as the business address for these returns.

A private mailbox at a UPS Store or similar Commercial Mail Receiving Agency is a different animal. It works as a mailing address, not as a substitute for where the business operates. Formatting is where people run into trouble. USPS requires a CMRA address to carry a “PMB” designation, so the correct form looks like “123 Main Street PMB 456” rather than “123 Main Street, Suite 456.” Mail sent without the PMB label (or a “#” sign as a substitute) can be returned as undeliverable. USPS also accepts the PMB number on its own line above the CMRA street address.⁵ If you list a CMRA on Lines 4a–4b of your EIN application, you still need to supply your real physical location on Lines 5a–5b.

Routing IRS Mail to an Accountant or Attorney

Both Form 1120 and Form 1065 let you receive mail “in care of” a third party such as an accountant, attorney, or management company. On Form 1065, the instructions say to enter “C/O” on the street address line, followed by the third party’s name and their street address or P.O. Box.² That gives you a stable point of contact if the owners travel or the business moves often.

Form 2848 lets you designate a representative to receive certain correspondence, but it doesn’t change the address of record with the IRS. To do that, you need Form 8822-B.⁶

Why the Wrong Address on File Is a Real Financial Risk

The IRS treats your “last known address” as the address on your most recently filed and properly processed federal tax return, unless you’ve clearly notified the agency of a new one.⁷ The agency also checks the USPS National Change of Address database, which holds forwarding data for 36 months. Telling your bank or your state DMV about a move does not count.

When the IRS mails a statutory notice of deficiency (the letter that starts the clock on your right to challenge a proposed tax increase in Tax Court), it goes to that last known address. You have 90 days to respond, or 150 days if the notice goes to an address outside the United States. The deadline runs whether or not you actually receive the notice.⁸ If the notice comes back undeliverable and the statute of limitations still has time on it, the IRS should reissue it. If the statute has run out, the agency can assess the tax based on your non-response to the original notice.

Form 8822-B puts it plainly: if you fail to give the IRS your current mailing address, “you may not receive a notice of deficiency or a notice of demand for tax. Despite the failure to receive such notices, penalties and interest will continue to accrue on any tax deficiencies.”⁶ The IRS doesn’t have to prove you received the letter; it only has to prove it sent the letter to the right address.

How to Update Your Business Address

Form 8822-B, Change of Address or Responsible Party — Business, is the primary tool. It handles changes to your mailing address, your physical business location, or the identity of your responsible party.⁹

Filing the form for an address change is voluntary, and there’s no penalty for skipping it. A change in responsible party is different and must be reported within 60 days.⁹ The form must be signed by an authorized person: an officer, owner, general partner, LLC member-manager, plan administrator, fiduciary, or authorized representative.⁶

Where you send it depends on your state, with businesses in the eastern half of the country generally mailing to Kansas City, MO and those in the western half mailing to Ogden, UT.¹⁰ Processing generally takes four to six weeks.⁶

You can also update your address by checking the “address change” box on Form 1120 or Form 1065.¹² That works, but the change won’t take effect until the IRS processes the return. If you move midyear and wait until filing season, months of IRS correspondence could go to the old address. Filing Form 8822-B right after you move closes that gap.

1
Internal Revenue Service. Instructions for Form 1120 (2025) – Section: Name and Address
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Internal Revenue Service. Instructions for Form 1065 (2025) – Section: Name and Address
3
Internal Revenue Service. Instructions for Schedule C (Form 1040) (2025) – Section: Line E
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Internal Revenue Service. Instructions for Form SS-4 (12/2025) – Section: Specific Instructions
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Federal Register. Delivery of Mail to a Commercial Mail Receiving Agency – Section: 2.6 Delivery to CMRA
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Internal Revenue Service. Form 8822-B (Rev. December 2019) – Change of Address or Responsible Party – Business
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eCFR. 26 CFR 301.6212-2 – Definition of Last Known Address
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Internal Revenue Service. 4.8.9 Statutory Notices of Deficiency
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Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party – Business
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Internal Revenue Service. Where to File Form 8822-B