Form 1120 Corporate Tax Return

What Address Goes on Form 1120? Principal Office vs Mailing Address Explained

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Written byLipai WangFounder · IRS-registered tax professional

Key Takeaways

Use principal office address, not registered agent address
IRS explicitly prohibits registered agent address as business address
Use C/O formatting for reliable U.S. mail delivery
Keep addresses consistent across forms

Principal Office vs Mailing Address

The Form 1120 address should be your principal office or place of business — not the registered agent's address. The IRS instructions explicitly prohibit using the registered agent address.

C/O Address for Foreign Owners

If your principal office is overseas, use C/O formatting to route mail through a reliable U.S. third party: C/O [Third Party Name], [Their Address]. Keep addresses consistent between Form 1120 and Form 5472 Part I.

Frequently Asked Questions

Can I use my registered agent's address?

No. The IRS Form 1120 instructions explicitly prohibit this. Use C/O formatting instead.

form 1120corporate taxforeign-owned LLC

IRS Form 1120 Instructions

Official IRS source on irs.gov

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