Form 5472: the 4 mistakes that trigger an IRS letter

A client we'll call AMBERLEAF came to us in mid-2025 with two years of returns he'd done himself. He had a single-member LLC in New Mexico, not a single dollar of tax owed — and he was still one step away from a $25,000 penalty. Because of an information return he didn't know existed.

That return is Form 5472. We reviewed it before filing anything and found three of the four mistakes that most often trigger an IRS letter. We fixed them in time. The letter never came.

Preparing returns for non-resident LLCs, we see the same four mistakes over and over, and they all share one thing: they have nothing to do with how much you earned, only with how you filed. Here's what triggers each one and how to avoid it.

Why the 5472 punishes so hard

If your LLC has a single owner who isn't a US person, the IRS treats it as a disregarded entity: for tax purposes the company "doesn't exist" and everything is looked at as if it were you directly. That sounds like there's nothing to file — and that's exactly the trap. Since 2017, that same disregarded LLC has been required to file Form 5472 every year, even if it never invoiced a cent.

The 5472 doesn't calculate tax. It's an information return: it tells the IRS what money moved between your LLC and you (or any related party abroad). And here's what makes it different from almost everything else: the penalty for not filing it, filing it late, or filing it incomplete is $25,000 to start — not a percentage of what you owe, a flat number. Ignore the IRS letter and it adds another $25,000 every 30 days. A company with zero income can end up with a five-figure penalty over a single badly done form.

That's why the 5472 is the form where a mistake costs the most relative to the effort. It's not that it's hard to understand; it's that it's merciless with oversights. And the oversights are almost always these four.

The 4 mistakes that trigger the letter

1. Filing the 5472 "loose," without the pro-forma 1120

Form 5472 isn't filed on its own. It has to be stapled to a Form 1120 (the corporate income tax return) filled out in pro-forma mode: just your LLC's name, address, and EIN at the top, and the rest blank. The 1120 here pays nothing — it's the mandatory "envelope" the IRS requires in order to accept the 5472.

The mistake is understandable: because your LLC is disregarded and pays no corporate tax, many people assume the 1120 doesn't apply to them and send the 5472 by itself. To the IRS, a 5472 without its pro-forma 1120 is an unfiled form. Same penalty as if you'd sent nothing.

The fix: the 5472 and the pro-forma 1120 are a single piece, always together. If you already filed the 5472 alone in prior years, it's worth checking whether those years are technically unfiled — they can be remediated, but it's far cheaper before the letter arrives.

2. Miscounting the reportable transactions

The heart of the 5472 is the list of reportable transactions: the flows of money between your LLC and you as the foreign owner. For a foreign-owned disregarded entity LLC, these transactions are reported in Part V of the form (not Part IV, which is for conventional corporations). Here the mistake is almost never inventing transactions — it's forgetting the ones that count.

The typical misunderstanding: "I didn't sell anything to myself, so there's nothing to report." False. For a disregarded entity, the money you put in to fund the LLC (the capital contribution) and the money you take out (distributions) are reportable transactions. Even if your LLC didn't invoice anyone, the mere fact of having funded it with your own money already generates a transaction that belongs on the 5472.

The fix: reconstruct the entire flow between your personal account and the LLC's during the year — contributions, withdrawals, expenses you paid out of pocket. Each one has its place in Part V. A 5472 that reports "zero transactions" when there was a transfer to open the account is, almost by definition, incomplete.

3. Confusing the EINs: the LLC's vs. the owner's number

The 5472 asks for two different identifiers and it's easy to mix them up. One is your LLC's EIN: that one is mandatory, the LLC needs its own EIN to file (your personal number won't do). The other is your identifying number as the foreign owner, and this is where people get stuck or lose months.

The most expensive confusion is believing you need a US ITIN or SSN just to own the LLC and file the 5472. In general you don't: as a non-resident individual without a US tax number, the form lets you report your tax ID from the country where you live. Some people delay their return half a year chasing an ITIN they didn't need — and meanwhile the 5472 deadline keeps running.

The fix: separate the two numbers from the start. Get the LLC's EIN as soon as possible — if you're not sure what it is or how to request it, we explain it in our EIN guide. And for your owner field, use your foreign tax ID where the form allows it, without chasing an ITIN that probably doesn't apply to you.

4. Missing the deadline (and assuming the extension is automatic)

The 5472 + pro-forma 1120 combo is due on April 15 (for a calendar tax year). It can be extended to October 15, but only if you file Form 7004 on time, before April 15. The extension doesn't happen on its own: if you don't request it, you don't have it.

Two false beliefs trigger this mistake. The first: "since I don't owe tax, there's no rush." The 5472 is an information return — the $25,000 penalty doesn't depend on you owing money, it depends on you being late. The second: confusing this deadline with others you do know, like the FBAR's October date, and assuming the 5472 works the same. It doesn't: if you didn't request the extension in April, in April it was due.

The fix: mark April 15 as the real date. If you won't make it with the complete return, file Form 7004 before that date to buy time until October. A perfect 5472 turned in on April 16 without an extension is already a late 5472.

The underlying pattern: the 5472 doesn't penalize you for earning money or for getting a tax figure wrong — it penalizes you for mistakes of form. The missing envelope, the forgotten transaction, the number in the wrong box, the day too late. All avoidable.

Why we don't recommend consumer tax software

The logical reaction is to open whatever TurboTax or FreeTaxUSA and knock it out in an afternoon. The problem is that that software doesn't support the 5472 + pro-forma 1120 combo for a single-member LLC with a foreign owner. It's not that it does it badly: it doesn't do it at all. You end up either not filing the 5472, or filing a regular 1120 that doesn't match your situation. And if dodging that tempts you to hand it to the cheapest preparer you can find, it's worth seeing first what filing the 1120 + 5472 really costs and where the trap is.

We also don't recommend the other extreme: overpaying for a structure you don't need "to be safe." A non-resident SMLLC with the 5472 done right is in compliance; you don't need to turn it into something else to be in order. The expensive mistake isn't the structure — it's the information paperwork, and that gets fixed by doing it right, not by complicating it. If you want the breakdown of what an LLC really costs to maintain, we cover it in the real cost of an LLC.

The result with AMBERLEAF

In AMBERLEAF's case, three of the four mistakes came together. He had filed the 5472 loose in his first year (mistake 1), hadn't reported the capital contribution he used to fund the LLC because he "hadn't sold anything" (mistake 2), and had started processing an ITIN he didn't need, which had made him late the prior year (mistakes 3 and 4 linked).

We redid both years with the pro-forma 1120 stapled, reported the actual contributions and distributions in Part V, used his tax ID from his country of residence, and got the deadlines under control. We filed with the root cause resolved and, several months later, no IRS letter.

What didn't go "perfectly": one of the two years was still filed late, because the mistake predated his coming to us. It had to be accompanied by a reasoned explanation of the delay. That's why we insist so much on getting the first 5472 right — undoing an oversight always costs more than avoiding it.

Checklist before filing your 5472

Before you call your LLC's information return done, run through this:

• Pro-forma 1120 stapled to the 5472: LLC name, address, and EIN at the top, the rest blank. Never the 5472 loose.
• Complete reportable transactions: include the capital contributions and distributions between you and the LLC, not just sales. If you funded the account, there was a transaction.
• The LLC's own EIN (not your personal number), and your owner field with your foreign tax ID if you don't have a US TIN — without chasing an ITIN that may not apply.
• The April 15 deadline on the calendar; if you won't make it, Form 7004 filed before that date to extend to October.
• Prior years: if you filed the 5472 alone or didn't file it, review it before the letter arrives — remediating in time is far cheaper.

The 5472 is scary because of the penalty, but the penalty almost never arrives over something sophisticated: it arrives over one of these four oversights. If you treat it as what it is — an information return that's merciless with form, not substance — you stop being an easy target. The substance — having a real business behind it — is a different story, one that banks and authorities weigh when they assess your LLC's economic substance. And if the idea of doing it yourself is tempting, it's worth reading first why "it's easy, I'll do it myself" is the most expensive sentence on the 5472.