Form 5472: Fax or Mail? Which Submission Method Is Safer

There is exactly one IRS fax number for the foreign-owned disregarded-entity Form 5472 package: 855-887-7737. You fax the complete return — the pro forma Form 1120 on top with Form 5472 attached behind it — in a single transmission. Write your EIN on every page so the pages stay together if they separate on the IRS end. For the canonical contact details, see our Form 5472 fax number and mailing address page.

The mailing address for a foreign-owned disregarded entity is P.O. Box 149342, Austin, TX 78714-9342. This is a P.O. box, so a courier such as FedEx or UPS that requires a street address cannot deliver to it — use the US Postal Service. Certified mail with a return receipt gives you a dated postmark, which is the evidence the IRS treats as proof of timely filing. Our full how to file Form 5472 walkthrough covers assembly and packaging.

Why early mailing matters

Postal transit to Austin from outside the United States can run 7 to 15 calendar days, and international mail is unpredictable. If you are filing from abroad and relying on mail, send the package at least two to three weeks before the deadline. If you are already close to April 15, switch to fax instead.

Speed is the single biggest practical difference between the two methods. A fax is delivered the moment the transmission completes, and your machine or fax service prints a confirmation page with the date, time, and destination number. Mail depends on the postal system: it must physically travel to the Austin P.O. box and be processed there.

For a foreign owner filing from another time zone, fax also removes any dependence on local postal service quality. Read more on the fax number and address reference.

“Safer” here means the lowest risk of a late or lost filing. Fax wins on both counts: it cannot be lost in the mail, and the confirmation page is dated the moment the IRS machine receives it. Mail can be delayed, misrouted, or arrive after April 15 — and with a flat $25,000 penalty at stake, a few lost days matter. If you have any doubt about timing, fax to 855-887-7737 and keep the page.

The two non-negotiable rules

First, a foreign-owned disregarded single-member LLC cannot e-file Form 5472 — only fax or mail are accepted. Second, whichever you choose, keep the proof. Without a confirmation page or certified receipt, you have no way to show the IRS you filed on time. See what happens if you don’t file for the consequences.

A single-member LLC owned by a non-US person is “disregarded” for income-tax purposes — its activity normally flows onto the owner’s return. But final regulations under T.D. 9796, effective for tax years beginning on or after January 1, 2017, treat the LLC as a corporation solely for Form 5472 reporting. Because the entity files no real income-tax return, the IRS e-file systems have no path for it; the pro forma Form 1120 exists only as a cover sheet to carry Form 5472.

That is why the IRS publishes a dedicated fax number and a P.O. box for these filings instead of accepting them electronically. The full mechanics are in our filing guide.

Proof of timely filing is your only defense if the IRS later claims it never received your return. Store the evidence with your tax records for that year — both digitally and on paper.

Because the penalty under IRC §6038A(d) has no cap and no statute of limitations, a return the IRS believes was missing can be assessed years later — your dated proof is what closes the question.

A late, lost, or incomplete Form 5472 triggers a $25,000 penalty per form, per year. If the IRS issues a 90-day notice and you still do not file, another $25,000 is added for each 30-day period that follows. The penalty is independent of whether the LLC owed any tax or earned any revenue — it is a pure information-return penalty.

This is exactly why the choice between fax and mail matters near the deadline: a missed April 15 because mail arrived late carries the same $25,000 cost as never filing. Read the full rule on the complete guide and the section breakdown in Parts I through IX explained.

The deadline is the 15th day of the 4th month after the tax year ends — April 15 for a calendar-year LLC. A timely Form 7004 pushes the filing deadline to October 15, but it only extends the time to file, not any payment (a disregarded entity has no entity-level tax). Whether you file on the original or extended date, the method is the same: fax to 855-887-7737 or mail to Austin, TX 78714-9342.

Note that BOI is a separate matter: under FinCEN’s March 2025 interim final rule, US-formed entities — including foreign-owned US LLCs — are exempt from beneficial-ownership reporting, and only foreign reporting companies file. Form 5472 is unaffected and still required. To start your filing, visit the apply page or compare on pricing.