You can use your registered agent’s address for an EIN application, but only on the mailing address lines of Form SS-4. The physical address lines require the actual location where your business operates, and a registered agent’s office does not qualify unless you truly work from there. Form SS-4 treats the two addresses as separate fields with different rules, and mixing them up causes processing delays and misrouted IRS mail.
Registered Agent Address on the Mailing Lines
Lines 4a and 4b of Form SS-4 collect the entity’s mailing address, meaning the place where the business wants to receive IRS correspondence. The IRS describes this as the address for the entity’s mail, and it generally appears on all future tax returns.1Internal Revenue Service. Instructions for Form SS-4 (12/2025) A registered agent’s office fits naturally here. Agents are already equipped to receive and forward legal documents and government notices, so routing IRS letters through them keeps mail from getting lost.
Using the agent’s address on Lines 4a–4b triggers a follow-up requirement: you must also complete Lines 5a and 5b with a separate physical address. The only time you can leave Lines 5a–5b blank is when the mailing address and the physical address are the same, such as when you both operate and receive mail at your home.1Internal Revenue Service. Instructions for Form SS-4 (12/2025)
Why the Physical Address Lines Are Different
Lines 5a and 5b ask for the entity’s physical address, and the IRS instructions state that P.O. boxes are not allowed.1Internal Revenue Service. Instructions for Form SS-4 (12/2025) The instructions do not name registered agents specifically, but they require the entity’s own physical address, meaning the location where the business is actually managed or where its records are kept. A registered agent’s office is the agent’s place of business, not yours. Listing it on Line 5 misrepresents where your company operates.
The IRS uses this address to identify the correct tax jurisdiction and to route compliance notices to people who actually run the business. Entering a location where nobody at your company works can send mail to the wrong place, prompt follow-up inquiries, or create confusion during an audit.
What to Put on Line 5 Instead
If you lease office space, use that street address. If you run the business from home, your home address is the appropriate entry, even if you would prefer to keep it off public state filings. The registered agent’s address can still shield you on the mailing side of the form and in state records; the physical address on Line 5 is a federal tax field, and it needs to reflect reality.
A quick summary of how the address fields interact:
- Lines 4a–4b are for the mailing address, and a registered agent’s address is acceptable here.
- Lines 5a–5b are for the entity’s physical location, required whenever it differs from the mailing address, with no P.O. boxes and no third-party offices where you don’t actually work.
- If both addresses are the same, complete only Lines 4a–4b and leave 5a–5b blank.
If You Switch Registered Agents Later
Your address on file with the IRS is not permanent. If your business moves, you change registered agents, or the mailing address you listed becomes outdated, file Form 8822-B, Change of Address or Responsible Party – Business, to update your record. The same form covers changes to the responsible party, and those changes must be reported within 60 days.2Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party – Business
Skipping this step is a common way to miss tax notices. If penalty letters accumulate at an old agent’s office, you may not learn about them until the balance is much larger and harder to resolve. When you switch agents, sending Form 8822-B promptly keeps IRS correspondence flowing to the right place.
Banks Will Ask for a Physical Address Too
The physical-address question does not end with the EIN. When you open a business bank account, federal anti-money-laundering rules require the bank to collect an address for every business customer. For entities such as corporations, partnerships, and trusts, the bank must obtain a principal place of business, local office, or other physical location, not just a mailing address.3FFIEC. Assessing Compliance with BSA Regulatory Requirements – Customer Identification Program A registered agent’s address typically will not satisfy that requirement either, because the bank needs to know where the business actually operates.
Keeping the same physical address across your IRS record and your bank paperwork reduces back-and-forth requests for documentation. You can still use the registered agent’s address as your public-facing mailing point and on state filings, while reserving your true physical location for the fields that require it.