The three-field map Lines 4a–4b tell the IRS where to send correspondence. Lines 5a–5b provide the entity’s physical address only when it differs. Line 6 identifies the entity’s primary physical business location.

Lines 4a–4b: mailing address

Enter the address where the entity can reliably receive IRS correspondence. The IRS says this address will generally be used on tax returns. If line 3 names an executor, trustee or “care of” person, line 4 uses that person’s address.

For an address outside the United States or its territories, include:

  • Street and unit details needed for delivery
  • City
  • Province or state
  • Postal code
  • Country name written in full—do not abbreviate it

Lines 5a–5b: physical street address

Complete these lines only if the entity’s physical address differs from the mailing address on line 4. The IRS explicitly says not to enter a P.O. box on line 5. A foreign physical address uses the same city, province/state, postal-code and unabbreviated-country details.

Same mailing + physical addressLine 5 can be blank

The SS-4 instructions ask for the physical address only if it differs from line 4.

Different physical addressComplete line 5

Use the actual street location; a P.O. box is not allowed.

Line 6: principal business location

The IRS instruction is brief: enter the entity’s primary physical location. The label asks for the county and state where the principal business is located. Use the real operating facts; do not invent a U.S. county simply to fill the space.

A registered agent is not automatically the business A registered agent receives state legal documents. That address should appear as the entity’s mailing address, physical address or principal business location only when it genuinely performs that role. State formation in Wyoming or Delaware does not by itself make the registered-agent office your principal physical business.

Three examples without invented addresses

Founder works and receives mail abroad

Use the complete foreign delivery address on line 4. If it is also the entity’s physical address, line 5 need not repeat it. Line 6 should reflect the true primary physical business location.

Mail goes to a controlled U.S. business mailbox

Line 4 may use the correspondence address if it reliably receives IRS mail. If operations occur elsewhere, line 5 identifies the different physical address and line 6 identifies the primary location.

Registered agent only

Do not copy the agent address into every field by default. Decide separately where IRS mail should go, where the entity is physically located and where its principal business occurs.

Address fields can affect more than mail

Fax and mail routing depends on whether the applicant has a legal residence, principal place of business, or principal office or agency in the locations named in the current instructions. Address facts therefore need to be internally consistent with the selected route. Phone adds a separate entity-organization test: a U.S.-organized corporation or LLC cannot use the international phone application route.

After the EIN is issued

Use Form 8822-B to report a later change to the business mailing address, location or responsible party. The IRS requires a responsible-party change to be reported within 60 days.

Pre-submission address check

  1. Can IRS correspondence actually reach the line 4 address?
  2. Is line 5 blank only because the physical address truly matches line 4?
  3. Is every country name written in full?
  4. Is there any P.O. box on line 5? Remove it.
  5. Does line 6 describe the primary physical location rather than formation state?
  6. Are the addresses consistent with the EIN application route?
Official IRS source The field definitions and foreign-address format come from the Instructions for Form SS-4, lines 4a–6. Download the current form from the official Form SS-4 page.