Expanding a business between the US and UK involves navigating two distinct legal systems, tax regimes, employment frameworks, and regulatory environments simultaneously. Whether you are a US business establishing a UK presence, a UK company entering the US market, or an entrepreneur structuring operations across both jurisdictions, the decisions you make at the outset have long-lasting tax and commercial consequences.
US Companies Entering the UK
UK Subsidiary vs. UK Branch
The first structural decision for a US company expanding to the UK is whether to establish a UK subsidiary (Ltd company) or a UK branch (permanent establishment) of the US parent:
- UK Subsidiary: A separate UK legal entity. UK Corporation Tax applies to UK profits. The subsidiary can be sold or restructured independently. Provides limited liability protection.
- UK Branch: An extension of the US parent in the UK. UK branch profits are subject to UK Corporation Tax, but the branch may also expose the US parent to additional UK tax complexity. The parent’s worldwide results are more directly intertwined.
From a US perspective, both structures can be treated as separate or transparent entities depending on elections made (e.g., the check-the-box election for the UK Ltd). The tax treatment of repatriated profits, transfer pricing, and intercompany transactions differs significantly between the two approaches.
Transfer Pricing
Transactions between a US parent and its UK subsidiary must be conducted at arm’s length under both US transfer pricing rules (IRC Section 482) and UK transfer pricing rules (TIOPA 2010). Inadequate documentation can result in significant adjustments and penalties from both the IRS and HMRC. We help establish transfer pricing policies, intercompany agreements, and documentation that withstands scrutiny on both sides.
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UK employers must operate PAYE, pay National Insurance Contributions, comply with auto-enrolment pension obligations, and adhere to UK employment law. US companies unfamiliar with UK employment practices frequently make costly errors. Our team coordinates with UK employment specialists to ensure full compliance from day one.
UK Companies Entering the US
US Entity Selection
UK businesses entering the US typically establish a US C-Corporation (often Delaware), LLC, or LLP. Choice of entity has significant implications for:
- US corporate tax rate (21% federal for C-Corp)
- State tax obligations (vary widely — some states have no corporate income tax)
- Pass-through treatment (LLC/LLP allows UK parent to be taxed on US income directly)
- Repatriation of profits back to the UK
- Eligibility for US tax treaty benefits
US Employer Identification Number and Tax Registration
UK companies doing business in the US need an EIN (Employer Identification Number) and must register for applicable state and local taxes. US payroll requires registration with the IRS and applicable state tax agencies, as well as compliance with US employment tax withholding (federal and state income tax, Social Security, Medicare).
Profit Repatriation and Withholding Taxes
When a UK subsidiary remits profits to its US parent (or vice versa), withholding taxes may apply. The US-UK Tax Treaty reduces withholding on:
- Dividends: 5% withholding (for 10%+ shareholders); 15% otherwise
- Interest: Generally 0% under the treaty
- Royalties: 0% for most royalties under the treaty
Planning the repatriation structure — dividends, management fees, royalties, intercompany loans — affects the overall effective tax rate on cross-border profits significantly.
The BEPS and Pillar Two Environment
The OECD’s Base Erosion and Profit Shifting (BEPS) framework and the Pillar Two global minimum tax (15% minimum effective rate, effective in the UK from 2024) have reshaped international tax planning. Businesses operating across the US and UK must now ensure their structures satisfy both countries’ anti-avoidance rules and the new global minimum tax regime.
Related services: Business & Corporate Tax | Cross-Border Tax Planning | Venture Capital & Tech