Top 5 Common Mistakes US Expats Make When Filing UK Taxes
Every year, thousands of US expats living in the UK face the daunting task of filing taxes in two countries. While the US is one of the few countries that taxes its citizens on worldwide income regardless of where they live, the UK also requires residents to report their income. This dual system creates a complicated environment for expats, and it is easy to make mistakes that lead to penalties, double taxation, or lost opportunities for tax efficiency.
One of the most common mistakes is misunderstanding residency rules. Simply living in the UK does not always mean you are automatically treated as a UK tax resident. The Statutory Residence Test determines residency status and considers factors such as time spent in the UK, ties to the country, and employment circumstances. Misinterpreting your residency can result in either underreporting or overreporting income, both of which carry risks.
Another frequent error is failing to take full advantage of the US–UK Tax Treaty. This treaty exists to prevent double taxation, but it is not automatic. Expats must file the correct forms to claim treaty benefits. Missing this step can mean paying more tax than necessary, as both the IRS and HMRC may claim the right to tax the same income.
A third issue is inadequate reporting of foreign bank accounts and assets. US citizens are subject to strict FBAR and FATCA reporting requirements, which apply even if the accounts are in the UK and used for day-to-day living. Many expats mistakenly believe these rules only apply to offshore tax havens, but in reality, they apply to all foreign accounts above certain thresholds. Non-compliance carries heavy penalties.
Another mistake is poor handling of pensions. UK pensions are treated differently under IRS rules compared to UK rules. For example, contributions to a UK pension scheme may be tax-advantaged in the UK but could still be taxable in the US unless correctly structured under treaty provisions. Mismanagement of pensions often leads to double taxation or missed reliefs.
Finally, many expats simply assume they can handle their tax filings without professional help. The combination of IRS regulations, HMRC rules, treaty provisions, and reporting requirements is complex. Even minor oversights can result in major financial consequences. Professional firms such as Xerxes Associates LLP provide tailored advice that ensures compliance while identifying opportunities for tax efficiency.
The reality is that living as a US expat in the UK comes with a unique set of tax responsibilities. By avoiding these common mistakes and seeking professional guidance, expats can ensure compliance, reduce their tax burden, and avoid unnecessary stress. Taxes do not need to be an obstacle to enjoying life abroad, but they do require careful attention.