Forming a US LLC does not remove you from the UK tax system. If you are a UK tax resident, HMRC taxes you on your worldwide income regardless of where that income originates or through which legal entity it flows. Income from your US LLC must be declared on your UK Self Assessment tax return, and the specific treatment depends on how HMRC classifies the LLC, the nature of the income, and the provisions of the US-UK Double Taxation Convention.
This is an area where UK-specific professional advice is important. US and UK tax rules interact in ways that are not always intuitive, and the same structure can have very different outcomes depending on how it is reported. This article provides the key concepts UK founders need to understand. For the US side of the picture, see our guides on Effectively Connected Income and Form 5472.
How HMRC Classifies a US LLC
The first and most important concept is that HMRC does not automatically accept the US tax classification of a foreign entity. While the IRS treats a single-member US LLC as a disregarded entity (transparent for US tax purposes), HMRC makes its own determination — and that determination can differ from the US classification.
HMRC's approach is to look at the characteristics of the foreign entity and compare them to categories recognised under UK law. A US LLC may be treated by HMRC as either transparent (with income flowing through to you personally, similar to a partnership) or opaque (with the LLC treated as a separate entity from a UK perspective, similar to a company). This classification has significant consequences for when and how the income is taxed in the UK. HMRC has published guidance on this, and its position has evolved over time. Obtaining confirmation of your LLC's UK classification before you begin operating is strongly advisable.
If HMRC Treats Your LLC as Transparent
If HMRC classifies your US LLC as transparent, the LLC's income is treated as arising directly to you as the UK-resident owner. You are taxed on the LLC's profits as they arise — not when you distribute money to yourself, but when the LLC earns it. This is the treatment that applies to UK sole traders and partners in UK partnerships, extended to an equivalent foreign entity.
Under this treatment, you declare the LLC's profits on your UK Self Assessment return in the foreign income section. The profits are subject to UK Income Tax at your marginal rate and potentially National Insurance Contributions if the income is classified as trading income. You are entitled to a credit for any US tax paid on the same income, avoiding double taxation under the US-UK treaty.
If HMRC Treats Your LLC as Opaque
If HMRC classifies your US LLC as opaque, the LLC is treated as a separate taxable entity from a UK perspective. You are not taxed on the LLC's profits as they arise — instead, you are taxed when money flows from the LLC to you personally, such as when you take a distribution or pay yourself a salary. This can create planning opportunities but also complexity. HMRC's Controlled Foreign Company (CFC) rules and Transactions in Securities legislation can apply to foreign-owned LLCs in certain circumstances, potentially preventing deferral of UK tax. These rules' application depends on the specific facts of your situation.
The UK Self Assessment Return
Regardless of how your LLC is classified, you must register for Self Assessment with HMRC if you have not already done so and have foreign income to declare. Self Assessment registration is required if your foreign income exceeds £2,000 in a tax year, or if you have any untaxed income that needs to be declared.
Foreign income from your US LLC is reported in the Foreign pages (SA106) of your Self Assessment return. The LLC's income is converted to GBP using the rate on the date of receipt or HMRC's published annual average rate.
The US-UK Double Taxation Convention
The US-UK tax treaty is designed to prevent the same income from being taxed twice. For UK founders whose US LLC income consists of remotely performed services with no US Effectively Connected Income, there may be little or no US tax to credit against UK tax. The income is taxed in the UK as your country of residence and not taxed in the US. Where US tax has been paid — for example, on US-source passive income subject to withholding — the UK provides a credit against UK tax for the US tax paid, subject to limits.
What You Should Do Right Now
If you are a UK resident who owns a US LLC and you are not currently filing a UK Self Assessment return that includes your US LLC income, address this as a priority. HMRC's requirement to declare worldwide income applies regardless of whether a formal demand has been made, and penalties for late filing and inaccurate returns apply from the date the obligation arose.
Working with a UK accountant who understands foreign corporate structures alongside our licensed Enrolled Agent Richard Williams — who handles the US side including Form 5472 and EIN management — gives you coordinated coverage of both jurisdictions.
Effectively Connected Income — When US Tax Applies
Form 5472 — Annual Federal Filing
Do Foreign LLC Owners Pay US Tax?
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