US LLC Formation for UK-Based Founders (2026): Tax Treaty, Banking & Setup Guide

A US LLC will not lower a UK tax resident's tax bill. HMRC taxes UK residents on worldwide income, including foreign business profit, no matter where the company sits. What a US LLC actually buys a UK founder is access: a US bank account with Mercury or Relay, and entry to US-only platforms that a UK LTD simply cannot open.

Why Would a UK Tax Resident Form a US LLC at All?

Because a UK LTD cannot open a Mercury or Relay account. Both banks require a US-formed entity as a condition of opening an account (per Mercury's own eligibility page), which is exactly the friction Stripe Atlas was built to solve for non-US founders in the first place.

If none of those three apply, a US LLC is probably solving a problem you don't have. Keep reading before you file anything.

Does Forming a US LLC Reduce Your UK Tax Bill?

No. If you are UK tax resident, you owe UK tax on your worldwide income, including profit earned through a foreign business, per gov.uk's guidance on foreign income. A US LLC changes nothing about that starting point.

The confusion usually comes from the US "disregarded entity" classification, which is a US federal tax construct describing how the IRS treats a single-member LLC. It has zero bearing on UK domestic tax law. HMRC runs its own, entirely separate analysis of how a US LLC is taxed once profit reaches a UK resident, and that analysis is the part that actually matters to you.

In our experience, founders sometimes assume "disregarded for US tax" quietly means "disregarded for UK tax too." It doesn't, and treating a US LLC as a UK tax-avoidance vehicle is the single most common mistake we see UK-based founders make when they read US-focused guides. Treat the LLC as a banking and operational tool, not a tax strategy.

What Does the US-UK Tax Treaty Actually Cover?

This is the real differentiator for UK founders: the US has a full income tax treaty with the UK, and GCC founders have none. Under Article 10 of that treaty, dividend withholding runs 5–15% depending on ownership, and interest and royalties are generally 0% (per HMRC's DT19852 manual and the IRS technical explanation), versus the flat 30% a founder with no treaty at all would face.

That last point matters more than the table itself. Most solo founders running an e-commerce or SaaS LLC earn ordinary trading profit, which US tax law calls Effectively Connected Income, not FDAP income. The treaty table above doesn't touch that category at all; it governs passive-style payments like dividends, interest, and royalties, a different bucket entirely. Don't read this table as "my LLC profit is taxed at 5%." It isn't what the table describes. For how ECI is actually taxed, see our guide to non-resident LLC income tax and ECI.

Is a US LLC Transparent or Opaque for UK Tax? The Anson v HMRC Question

In Anson v HMRC [2015] UKSC 44, a UK resident who was a member of a Delaware LLC won relief from double taxation after HMRC had treated the LLC as opaque, denied him credit for US tax already paid, and produced a combined effective rate near 67% on the same profit. The Supreme Court sided with Anson, but on the specific wording of his LLC's operating agreement, which gave him a present entitlement to profit as it arose.

Here's the part that trips people up: HMRC did not change its general approach after losing that case. Per HMRC's International Manual (INTM180050), updated December 2023, and its own Revenue and Customs Brief 15 (2015), HMRC maintains that most US LLCs are still opaque by default and reviews Anson claims case by case, arguing the ruling turned on that LLC's particular paperwork rather than LLCs generally.

The practical upshot: whether double-tax relief is available to you depends on wording most founders never read closely, the profit-distribution clause in their own LLC operating agreement. It's worth asking your formation provider for that document before you assume anything about how HMRC will treat it.

US LLC or Stick With Your UK LTD? A Decision Framework

Run this quick check before you file anything new. If your customers, payment rails, and banking are all UK/EU-based, a UK LTD is usually simpler and sufficient on its own, and a second US entity adds real complexity without a matching benefit.

A second entity means a second registered agent, a second annual compliance cycle, an annual Form 5472, and the Anson uncertainty above layered on top. We've seen UK founders form a US LLC purely out of habit, copying US-based advice threads, and then discover months later they never actually needed US banking in the first place. Don't add the complexity unless a concrete US banking or platform reason is driving it. For a fuller side-by-side, see our US LLC vs UK LTD comparison.

How Do You Actually Form and Bank a US LLC from the UK?

Formation mechanics are the same as for any non-resident owner, with one banking wrinkle UK founders need to plan for. You get an EIN through Form SS-4, marking box 7b "Foreign," with no SSN or ITIN required.

Because your principal place of business sits outside the US, you can't use the IRS's online EIN tool; instead you apply by phone, fax, or mail, which typically adds a few business days versus the instant online result US-resident applicants get. Most UK founders never need an ITIN at all, since the EIN process bypasses it entirely; you'd only need one later if you must personally file Form 1040-NR because of US-source Effectively Connected Income.

Banking is where the practical UK-specific friction actually shows up. Mercury doesn't require an SSN or ITIN, but as of 2026 it expects a genuine US operating address, not just your registered agent's address, so plan for a US virtual mailbox service before you apply. Relay, by contrast, requires an SSN or ITIN outright, which makes it a harder route for a UK founder who hasn't needed either before. Compare both options in our US business banking guide for non-residents.

What Ongoing Compliance Does a UK Founder Need to Handle?

Every foreign-owned single-member LLC owes an annual Form 5472 alongside a pro forma Form 1120, and a UK owner faces the exact same rule as any other non-resident owner, with no UK-specific exception. Miss it, and the IRS penalty is $25,000 per omitted or inaccurate filing.

You'll also need a registered agent in your formation state, renewed annually, exactly as any non-resident owner does. None of this changes because you're UK-based rather than, say, UAE-based; the only genuinely different pieces for a UK founder are the treaty rates on FDAP income and the Anson question covered above. See our annual compliance checklist and Form 5472 guide for the full filing walkthrough.

US LLC Formation for UK Founders — FAQ