New UK tax year: 5 things Americans in the UK should do now

Key takeaways

Conduct proactive residency checks: Don’t assume your residency status is static. Changes in travel or work can shift how you are taxed on worldwide income. Confirming this early sets the foundation for your entire tax strategy.

Coordinate cross-border investments: Many common UK investments can trigger punitive US tax rates, while US funds may be taxed heavily in the UK. Regular reviews are essential to ensure your portfolio is tax-efficient in both countries.

Manage timing mismatches: Because the UK and US tax years don't align, you can face temporary double taxation. Planning the timing of your income and asset sales helps you better use foreign tax credits to offset these costs.

The UK tax year began on 6 April, and for Americans living in the UK, it’s an important opportunity to reset and plan ahead. Unlike most taxpayers, US citizens must navigate two tax systems at the same time. This makes early planning essential, not just for compliance, but for managing your overall tax position efficiently.

By taking a proactive approach at the start of the year, you can reduce complexity and avoid costly surprises later on. Here are our top five things to do early on in the year

1. Confirm your UK tax residency status

The starting point each year is confirming your UK tax residency under the Statutory Residence Test. This determines whether you are taxed on your worldwide income and gains or only on UK-source income. For many Americans living full-time in the UK, this may seem straightforward. However, changes in travel patterns, working arrangements, or time spent abroad can impact your status. Taking the time to review this early ensures that everything else - from investment planning to tax reporting - is built on the correct foundation.

2. Plan pension contributions early

UK pensions remain one of the most effective tools for long-term tax-efficient savings. The UK offers tax relief on contributions and tax-deferred growth, making them highly attractive from a domestic perspective. However, the US treatment is not always aligned. Depending on the structure of the pension and how treaty provisions apply, contributions and growth may be treated differently, and additional reporting obligations can arise. Because of this, timing and structuring contributions properly is key. Starting early in the tax year gives you more flexibility to make use of allowances, manage cash flow, and ensure that your pension strategy works across both tax systems.

3. Use your UK allowances

A new tax year brings a fresh set of allowances, including those for ISAs, pensions, and capital gains. These can be valuable tools in reducing your UK tax liability if used effectively. The key is to consider these allowances as part of a broader cross-border strategy, rather than viewing them in isolation.

4. Review your investment portfolio

Investment planning for Americans in the UK requires careful coordination. Many UK-based funds are treated as Passive Foreign Investment Companies (PFICs) for US tax purposes, which can lead to complex reporting and punitive tax outcomes. At the same time, US-domiciled funds can create problems in the UK if they do not have reporting status with HM Revenue & Customs. In those cases, gains may be taxed as income rather than capital, resulting in significantly higher tax rates. This mismatch means that an investment that works well in one country may be highly inefficient in the other. Reviewing your portfolio at the start of the tax year helps ensure it remains aligned with both systems and avoids issues that are difficult to fix later.

5. Plan for double taxation and timing

Although Americans in the UK are subject to tax in both countries, double taxation is usually mitigated through foreign tax credits. In most cases, the UK taxes income first, with the US then providing relief.  However, this process is not always seamless. Differences in tax years can create timing mismatches. Income or gains may be taxed in one country before relief is available in the other, leading to temporary double taxation. By planning ahead, particularly around the timing of income and disposals, you can improve the efficiency of foreign tax credit claims and avoid unnecessary cash flow issues.

Final thoughts

For Americans living in the UK, tax planning is not just about meeting filing deadlines it is about managing the interaction between two complex systems.

Taking time at the start of the tax year to review your residency, pensions, investments, and overall strategy can make a significant difference. With the right planning in place, you can reduce your tax exposure, simplify compliance, and approach the year ahead with greater confidence.

Glossary of key terms

Statutory Residence Test (SRT): The set of rules used by the UK government to determine whether an individual is considered a UK resident for tax purposes.

Tax Relief: A government policy that reduces the amount of tax an individual has to pay, often used in the UK to encourage pension contributions.

Passive Foreign Investment Company (PFIC): A US tax designation for non-US pooled investments that often results in complex reporting and high tax rates for Americans.

HMRC Reporting Status: A status granted by the UK tax authority to offshore funds that agree to report certain data.

Foreign Tax Credits (FTC): A US tax credit used to offset income taxes paid to a foreign government against US tax liability on the same income, preventing double taxation.