"It's easy, I'll do it myself" — The Dunning-Kruger trap of Form 5472

It's Friday afternoon. In one of those random "entrepreneurs around the world" WhatsApp groups — the ones that add you without asking — the classic thread about US taxes shows up. Someone asks for recommendations. Another person says they did it themselves. And then The Know-It-All appears.

"You can do it yourself, it's easy, simple and works for the whole family."

This line, said with the confidence of someone who just discovered Wikipedia, inspired this post. It's the Dunning-Kruger effect applied to the IRS: the curve where the people who know the least about a topic are the most certain when giving advice. The catch is that, in tax filing, that confidence costs exactly $25,000 in base penalties.

Here's the chat — recreated with names changed, because the original had too many personal details:

What Dunning-Kruger looks like at the IRS

The Dunning-Kruger effect says incompetence prevents you from recognizing your own incompetence. Applied to Form 5472, that means one very specific thing: the person who has never seen a Reportable Transaction Code, a Part I–III check, or a Related Parties declaration is the one who will tell you fastest that "it's easy". Not because they're lying — because they literally have no idea what's inside the form.

The people who have actually filed a complete 5472 tend to say the opposite: it's the most specific informational form the IRS demands from foreign-owned SMLLCs, every box has a 47-page instruction manual, and the most expensive mistake isn't what you put in — it's what you leave out.

The 5 holes in the DIY approach

1. PTIN — the credential nobody has

The IRS requires that anyone who gets paid to prepare a tax return hold a PTIN (Preparer Tax Identification Number). Not optional. Your accountant cousin back home doesn't have one. The $30 person on Fiverr doesn't either. The lifelong family bookkeeper doesn't.

That has two awkward legal consequences: if they sign as preparer without a PTIN, they're committing fraud against the IRS. If they don't sign, the only person responsible to the IRS is you. There's no middle ground: either the person who got paid takes responsibility, or you take all of it.

2. TurboTax doesn't do 1120 pro-forma

This shocks people who've filed US taxes before: TurboTax, H&R Block, FreeTaxUSA and the rest of consumer software do not support the 5472 + 1120 pro-forma combo for foreign-owned single-member LLCs. Period.

If anyone tells you they do, ask them how they check the "pro-forma return" box on the 1120 (hint: it doesn't exist in consumer software). The combo is only prepared with professional software (Drake, Lacerte, UltraTax) or by hand on paper, and submitted by physical mail or fax — the IRS does not accept e-file of the 5472 in this case without a preparer's EFIN.

3. Related Parties — the 95% blind spot

Form 5472 exists for one specific reason: to give the IRS visibility into all transactions between the LLC and its related parties. That includes:

• You, the owner (any distribution or capital contribution).
• Your spouse or direct family (if there are transactions).
• Your holding or any other LLC/corp where you own >25%.
• Companies controlled by the same owners.

95% of the DIY filings I've reviewed leave out at least one Related Party. And this matters: the IRS cross-references bank data (FATCA + CRS) with what you declare. When the "transactions with related parties" box is empty but Mercury reports a transfer to an account with the same beneficial owner, an alert fires.

4. Reportable Transaction Codes

The 5472 doesn't ask you to describe transactions in prose. It asks you to code them using IRS-specific codes (Sales of stock, Loans received, Rents, Royalties, Commissions, etc.). There are 13 categories and each one has its own associated Part III. Coding something incorrectly isn't a cosmetic error: it's a discrepancy that triggers manual review.

5. Submission — the last nail

Once the 5472 is well prepared, there's still the submission: the IRS demands certified mail with return receipt or fax to a specific number (which has changed 3 times in the last 2 years). Anyone who sends it by regular mail has no proof of delivery — and if the IRS "never received it", the no-filing penalty kicks in anyway.

"My accountant cousin back home"

A foreign CPA, a chartered economist, a lifelong tax advisor — none of them are authorized to prepare returns with the IRS. It's not about intelligence or years of experience: it's about jurisdiction. The IRS recognizes three legal preparer categories:

• CPA licensed in a US state.
• Enrolled Agent (EA) — federal exam specific to the IRS.
• Tax attorney licensed in the US.

Any other preparer must at least hold a PTIN to sign as paid preparer. A foreign accountant has none of these three credentials. That doesn't make them a bad professional — it makes it so they cannot sign your 5472.

"$30 on Fiverr"

The math is pure arithmetic:

• Fiverr cost: $30.
• Base penalty for incorrectly filed 5472: $25,000.
• Additional penalty every 30 days if you don't fix after notice: $25,000.
• Detection probability: increasing year over year (the IRS reported a 340% increase in audits of foreign-owned SMLLCs in 2024).

The expected value of DIY depends on your personal probability of being audited. If you think it's 0%, Fiverr is the best option. In any other scenario — even at 1% — the expected cost exceeds $250, which is already more expensive than any serious professional service.

When DIY does make sense

Not everything is doom and gloom. DIY can make sense if all of these conditions are met:

• Your LLC had $0 in transactions with related parties that fiscal year.
• You have no holding, no spouse, no other LLC/corp (clean Related Parties).
• You read the full official IRS instructions (about 90 pages).
• You can read Part I–III of the 5472 and know what goes in each box without Googling.
• You have the patience to send by certified mail and archive the return receipt for 7 years.

If you tick all 5, go ahead. For the remaining 99%, paying someone with a PTIN is the rational call.

The advice from the WhatsApp group

Back to the chat at the top: the problem isn't Victor. The problem is that in any digital-entrepreneur group there's a Victor for every tax question. And the people who ask tend to listen to whoever sounded most confident — not whoever knew the most.

If you're going to risk $25,000, at least let it be on advice from someone who has actually filed a 5472. Not on the certainty of someone who confused "I've paid my taxes back home" with "I know how the IRS works".

The cost of getting the 5472 wrong is 833x the cost of hiring someone to do it right. Run the numbers before you listen to the know-it-all.

If you've already filed taxes incorrectly or skipped a year, also see our guide on the 5 most common LLC owner mistakes. If you don't yet know whether your LLC needs to file a 5472, start with what the EIN is and how to know if your LLC is a Disregarded Entity or not.