Accountants for the US and the UK: How to Choose the Right Firm in 2025

Finding the right accountants for the US and the UK is one of the most consequential decisions a business owner, director, or investor can make. Whether you operate across both countries, hold dual residency, or manage assets on either side of the Atlantic, the financial and tax implications are significant, complex, and constantly evolving.

The rules governing US–UK taxation have never been more demanding. HMRC and the IRS both expect full compliance, and the consequences of getting it wrong — from penalties to double taxation — can be devastating for individuals and businesses alike. That is why choosing an experienced, cross-border accountancy firm is not optional. It is essential.

This guide is written for UK-based business owners with US interests, American entrepreneurs operating in Britain, dual-tax residents, and international investors seeking authoritative advice. By the end, you will know exactly what to look for, what questions to ask, and why the right firm can be the difference between financial clarity and costly confusion.

Why the US–UK Tax Relationship Is More Complex Than Most People Realise

The United Kingdom and the United States have a long-standing tax treaty — the US–UK Double Taxation Convention — but having a treaty does not mean the two systems align neatly. In practice, the differences in how income, capital gains, dividends, trusts, and pensions are treated across both jurisdictions create significant friction for anyone operating in both countries.

You can review the official treaty documentation here: https://www.gov.uk/government/publications/usa-tax-treaties

This means an American entrepreneur based in London must still file a US federal tax return every year and potentially pay US tax on income already taxed in the UK. At the same time, HMRC expects UK tax residents to declare global income. Without careful planning and the right professional in your corner, double taxation becomes a very real risk.

The Internal Revenue Service and HMRC each operate different reporting frameworks, filing deadlines, and penalty structures. Learn more about IRS obligations at: https://www.irs.gov

For HMRC guidance on UK tax obligations, visit: https://www.gov.uk/government/organisations/hm-revenue-customs

An accountant who understands only one side of the Atlantic will almost certainly leave costly gaps in your compliance and planning.

What to Look for When Choosing Accountants for the US and the UK

Dual-Jurisdiction Expertise and Professional Accreditation

Not every accounting firm is qualified to advise on both US and UK tax matters. In the UK, credible accountants should carry accreditation from the Institute of Chartered Accountants in England and Wales. In the US, Certified Public Accountants must be licensed at the state level. For transatlantic work, you want a firm that holds or works directly with both.

Find out more about ICAEW accreditation standards here: https://www.icaew.com.

Ask any prospective firm direct questions. Do they have qualified CPAs on their team? Can they prepare both US federal and UK self-assessment returns? Do they have experience with Foreign Bank Account Reporting and the Foreign Account Tax Compliance Act? These are not tick-box questions — they reflect the practical expertise your situation demands.

Experience with Cross-Border Business Structures

Whether you are incorporating in Delaware while running UK operations, setting up a UK subsidiary for a US parent company, or holding property in both countries, your accountant must understand the structural implications of cross-border entities. The OECD Model Tax Convention provides the international framework that governs many of these structures: https://www.oecd.org/en/topics/sub-issues/model-tax-convention.html.

Business structure decisions — LLC versus LTD, S-Corp versus sole trader, trust versus holding company — carry very different tax consequences depending on where you are resident, where you earn, and where your clients are based. A firm with genuine dual-jurisdiction experience will guide you through these decisions with authority, not guesswork.

Transparent Fees and Genuine Accessibility

International accountancy is not cheap, and it should not be. But it should be transparent. Look for firms that provide clear engagement letters, fixed-fee or capped arrangements where possible, and a named point of contact who actually responds to your calls and emails. The firms best placed to support you will make their pricing clear from the outset and proactively communicate when your situation changes.

Key Tax Issues That Require Specialist Accountants for the US and the UK

Residency, Domicile, and the Statutory Residence Test

Your tax residency status determines where and how you are taxed. In the UK, residency is assessed using the Statutory Residence Test. In the US, the Substantial Presence Test determines whether a non-citizen must file as a US tax resident. Full guidance on the UK Statutory Residence Test is available here: https://www.gov.uk/guidance/statutory-residence-test-srt.

Getting this wrong can expose you to liability in both countries simultaneously or lead to claims of tax evasion if disclosures are inadequate. Domicile adds another layer of complexity. For UK inheritance tax purposes, your domicile status — not your residency — determines your exposure. Many long-term UK residents are surprised to learn that their worldwide estate may be subject to UK inheritance tax even if they hold a foreign passport.

Transfer Pricing and Intercompany Transactions

If you operate a group structure with entities in both the US and the UK, transfer pricing rules will apply. Both the IRS and HMRC require that transactions between related parties be conducted at arm's length. Failure to comply can trigger significant penalties and reputational damage.

The OECD Transfer Pricing Guidelines underpin the rules in both jurisdictions: https://www.oecd.org/en/topics/sub-issues/transfer-pricing.html.

A firm without in-house transfer pricing expertise is not equipped to handle this work properly. This is an area where the difference between a general accountant and a specialist firm is measurable in tens of thousands of pounds.

Pension Planning Across Borders

US persons who hold UK pension plans — including SIPPs and workplace schemes — face particularly complex rules. The IRS does not automatically recognise UK pension structures in the same way HMRC does, and certain pension arrangements can trigger unexpected US taxable events. The reverse is also true: US 401(k) and IRA accounts are not always treated as pension vehicles under UK rules.

The Financial Reporting Council sets standards for financial advice in the UK. Any firm advising on cross-border pensions should work within these standards: https://www.frc.org.uk.

FATCA, FBAR, and Overseas Financial Reporting

FATCA — the Foreign Account Tax Compliance Act — requires US persons, including citizens and green card holders, to report foreign financial accounts and assets to the IRS. UK-based financial institutions also report account information on US persons to HMRC, which then shares it with the IRS. Non-compliance carries severe penalties, including fines of up to $10,000 per unreported account per year.

FBAR — the Report of Foreign Bank and Financial Accounts — is a separate obligation requiring US persons with overseas accounts exceeding $10,000 at any point during the year to file with the Financial Crimes Enforcement Network. If you are a US person living or operating in the UK, both obligations are mandatory and must be managed by a qualified specialist.

Red Flags to Avoid When Selecting a US–UK Accountancy Firm

Not every firm that claims to offer cross-border accountancy is genuinely equipped to do so. Watch out for firms that cannot name the specific US tax forms they prepare — such as Forms 1040, 5471, or 8938. Be cautious of advisers who focus only on one country's rules without acknowledging the implications of the other.

Avoid any firm that promises outcomes that seem too good to be true, particularly around offshore structures or aggressive tax mitigation strategies. Genuine expertise in accountants for the US and the UK means understanding that compliance is non-negotiable. Reputable firms will never suggest approaches that conflict with the financial transparency standards upheld by the Bank of England and the Federal Reserve.

For the Bank of England's regulatory standards, visit: https://www.bankofengland.co.uk.

For the Federal Reserve's financial oversight framework, visit: https://www.federalreserve.gov

Also, be wary of firms that are slow to respond, unclear about who is responsible for your account, or unable to provide client references with similar cross-border needs.

The Strategic Value of Getting This Right

Choosing the right accountants for the US and the UK is not just about compliance. It is about strategy. An experienced transatlantic firm will help you structure your business, your investments, and your personal affairs in a way that minimises your global tax burden within the law, protects your assets, and supports your long-term growth plans.

Consider a UK entrepreneur seeking capital from US investors. The structure of that fundraising — whether via a US parent, a UK subsidiary, or a joint venture — will have profound tax implications in both countries. Without the right advisory team, costly mistakes are made at the structuring stage before a single pound or dollar is raised.

Or consider a US executive relocating to London for a multi-year assignment. Their worldwide income, US retirement accounts, share options, and UK property all interact in ways that can either be managed efficiently or become a serious financial liability. The right firm addresses every element of that picture from day one.

According to Companies House, the number of US-affiliated companies registered in the UK continues to grow year-on-year. Each of those companies represents a business owner or director who needs exactly the kind of integrated tax and accountancy support that specialist firms like JungleTax exist to provide. You can verify company registration data at: https://www.companieshouse.gov.uk.

Why JungleTax Is the Trusted Choice for US–UK Accountancy

JungleTax operates as a dedicated UK–US advisory firm. Unlike generalist accountants who occasionally handle cross-border cases, JungleTax focuses specifically on the intersection of UK and US tax law, business structuring, and financial compliance. Every client receives advice that accounts for both jurisdictions from day one.

The JungleTax team understands the pressure that business owners and directors face when operating across the Atlantic. Whether you are managing an inbound US investment, preparing for a UK listing, navigating FATCA reporting, or simply ensuring your personal tax affairs are in order on both sides of the border, the firm brings the technical depth and practical experience to guide you through it with confidence.

Choosing accountants for the US and the UK with the right combination of credentials, cross-border experience, and genuine client focus is not easy. But it is one of the most important decisions you will make for your business and your personal financial future. JungleTax exists to make that decision straightforward.

Ready to Get Expert Cross-Border Accountancy Support?

If you manage financial interests across the UK and the United States, you cannot afford to work with an accountant who only understands half the picture. JungleTax provides integrated, expert accountants for US and UK services that business owners, directors, CFOs, and international investors across both countries rely on every day.

Contact JungleTax today to arrange your consultation and take control of your cross-border tax position.

Email hello@us-uktax.com Call 0333 880 7974

Our team is ready to review your current situation, identify risks and opportunities, and deliver a clear, actionable plan — across both jurisdictions, with no loose ends.

Frequently Asked Questions

What should I look for in accountants for the US and the UK?

Look for firms with verified credentials in both jurisdictions — ICAEW membership in the UK and CPA licensing in the US. Ensure the firm has hands-on experience with dual tax returns, FATCA and FBAR compliance, and cross-border business structures. Always ask for client references with similar international profiles before committing.

Do I need separate US and UK accountants?

Not necessarily. Specialist cross-border firms like JungleTax integrate both functions into a single advisory relationship. This avoids the miscommunication that often arises when two separate firms handle different parts of the same picture, and typically delivers better outcomes at a lower combined cost.

How does the US–UK tax treaty affect my tax liability?

The US–UK Double Taxation Convention is designed to prevent the same income being taxed twice. However, applying the treaty correctly depends on your specific residency status, the type of income involved, and the structure of your business or personal affairs. An experienced adviser will analyse each element to ensure you claim every treaty benefit available to you.

What is FATCA, and does it affect UK residents?

FATCA requires US persons — including citizens and green card holders — to report foreign financial accounts and assets to the IRS. UK financial institutions also report account data on US persons to HMRC. If you are a US person living or operating in the UK, FATCA compliance is mandatory and must be managed by a qualified cross-border adviser.

Can JungleTax help with both personal and business taxes in the US and the UK?

Yes. JungleTax advises on personal tax returns, corporate tax planning, business structuring, international payroll, cross-border pension issues, and regulatory compliance across both the UK and the US. Contact the team at or call 0333 880 7974 to discuss your specific requirements.

How do I know if I am a tax resident in the UK, the US, or both?

UK tax residency is determined by the Statutory Residence Test administered by HMRC. US tax residency for non-citizens depends on the Substantial Presence Test used by the IRS. It is possible to be tax resident in both countries simultaneously, which is precisely why dual-jurisdiction advice is critical. A qualified specialist will assess your position based on your full circumstances and history.