US Tax Traps Every EU Founder Should Know Before Moving

You've validated the product. You've got American interest. Maybe you've even spun up a Delaware C-Corp because that's what everyone said to do — and then you let it sit while you got the rest of the business ready.

No clients. No revenue. No problem, right?

That's exactly the assumption that springs the trap.

We sat down with cross-border tax specialist Carolin Hock (Hock Tax Services) for the StateMinded podcast, and the throughline of the entire conversation was one word she kept coming back to: exposure. Not tax bills — exposure. Because in the US, the thing that hurts founders usually isn't the tax they owe. It's the filings they didn't know existed. Here are the five traps she sees catch good companies with great products.

Trap 1: The "dormant" company that isn't dormant

This is the one that made us sit up. A European founder incorporates a US entity, has no clients, no profit, nothing happening — and assumes there's nothing to file.

As Carolin put it,

"even an inactive company has certain informational filing obligations."

Here's how it bites. Say three founders each wire twenty dollars to cover a registered agent. That tiny movement of money can trigger a requirement to file Form 5472 — an informational form for foreign-owned entities — for each of them. Miss it, and the civil penalty is $25,000 per form. Three founders, three missed forms, $75,000 in penalties for moving sixty dollars.

Founders constantly come to Carolin saying "we'd like to file our first return," she said — and the moment she asks when did you incorporate, the answer is "two years ago, but nothing happened." Then it turns out there was a wire. And, in her words, "that just changes everything."

The lesson: the instant you have a registered footprint of any kind, your foreign status alone can create obligations. Silence is not safety.

Trap 2: Picking the entity by convenience instead of strategy

The European reflex is "we'll just open an LLC." It's familiar, it's cheap, it feels simple. But Carolin's guidance is sharper: the right structure depends on where you're going, not what's easiest today.

If raising capital is anywhere on your roadmap, she leans hard toward a C-Corp — venture capital and most funding programs simply expect it. An LLC, by contrast, is "very much centered around the individual forming it" — it's intertwined with your personal tax status. So if you're a foreign founder who doesn't intend to become a "US person" (her wonderfully blunt term for someone who files a personal US return), the C-Corp often has a real leg up by keeping the company siloed from you.

And the choice isn't just Delaware-or-bust. Wyoming and Texas come up constantly.

What actually drives the decision is your goal and your existing European footprint — whether your US presence is a branch or a subsidiary changes everything. The mistake isn't choosing an LLC or a C-Corp. The mistake is choosing before anyone's asked you where you're headed.

Trap 3: America isn't one tax jurisdiction. It's hundreds.

We say the US isn't one market, it's fifty.

Carolin's correction: it's worse than fifty. "You have counties, you have cities." Federal, state, and local — layered on top of the split between direct tax (income) and indirect tax (sales tax, even personal property tax, where a city like DC wants to know how many desks and chairs sit in your office).

The word that ambushes everyone is nexus — the connection to a jurisdiction that makes it think you owe it something. For SaaS companies especially, this hides in the fine print: a product might not be taxable in the state of Illinois but absolutely taxable in the city of Chicago. Even something as innocent as 200 transactions to a single client can create nexus. That's why Carolin's team starts by reading your user agreements and mapping where your customers actually are.

But — and this is the part that flips doom into opportunity — getting it right is also a shield. If you genuinely have no boots on the ground in a state (no employee, no warehouse, no office), interstate-commerce protections can mean you file a protective return and owe zero income tax there. The patchwork that scares founders is also a map of where you're legally protected. You just have to read it on purpose.

Trap 4: The founder who accidentally becomes a US taxpayer

This is the personal landmine, and it's invisible until it detonates. Most founders know that spending serious time in the US can trigger income tax. What catches them is the math. The substantial presence test counts this year plus the two years before it — earlier years at a fraction. As Carolin warned, you can tip over the line "just because you had a long vacation two years ago."

And crossing it doesn't just touch your US income. US citizens and green-card holders are taxed on worldwide income — the US is one of the only countries on earth that does this. The goal Carolin fights for with most clients is to keep them taxed only on their effectively connected US income — paying their fair share on US operations — without getting pulled fully into the US system, where a whole separate problem opens up (more on that in our companion post on double taxation).

Trap 5: Cheap to get right, brutal to unwind — but never hopeless

Every trap above shares a shape: the fix costs almost nothing at the start and a fortune later. Structure is a foundation you pour once.

But here's the genuinely reassuring note Carolin ended on, and it's worth hearing if you're reading this in a cold sweat: even if you're already behind — sold into dozens of states, never filed a thing — don't despair. The US, she stressed, is "a very business-friendly jurisdiction," with voluntary disclosure programs that let you come forward and get back into compliance, often without penalties.

The real takeaway: understand your exposure

Carolin's closing line is the whole philosophy: "understand your exposure." The US isn't a tax nightmare — handled right, she calls it "a bit of a tax haven" for business. Get the structure and the filings right and it's "as easy as a strike of a pen." Get them wrong and the penalties pile up.

The catch: you need someone who actually lives in the cross-border world and works at your stage.

A firm whose typical client is a Fortune 500 won't know the small things that trip up a three-person founding team — and at a big firm, the smaller you are, the more junior the person you get.

That's exactly the gap StateMinded exists to close. We don't just point you at the American door — we walk through it with you, the right specialists alongside.

StateMinded Partner Network

Carolin described the "holy trinity" every founder needs from day one — a cross-border CPA, an attorney, and a banking partner. We're building exactly that: a vetted network of US specialists, including cross-border tax pros like Carolin, so you're never handed off to the most junior person in the room.

Planning your US move? Book a no-obligation US assessment with Carolin and StateMinded and let's make tax a foundation, not a trap.

This article shares general patterns from our conversation with Carolin Hock and isn't tax advice. Your exposure depends entirely on your specific situation — confirm anything here with a qualified cross-border advisor before you act.