US–UK Double Tax Calculator

Rarely in practice. Although the United States taxes citizens on worldwide income, the Foreign Tax Credit lets you offset UK tax paid against your US bill. Because UK income tax is usually higher than US tax on the same income, the credit typically eliminates any additional US liability, though you must still file both returns.

The Foreign Tax Credit gives you a dollar-for-dollar reduction in your US tax for income tax paid to another country, such as the UK. It is claimed on Form 1116. The credit is limited to the US tax attributable to that foreign income, but for UK residents it usually covers it in full.

It depends on your circumstances. The Foreign Tax Credit often suits higher earners in a high-tax country like the UK, because it can leave excess credits to carry forward and preserves the child tax credit. The Foreign Earned Income Exclusion can suit those in low-tax countries. Choosing correctly can save thousands, so advice is worthwhile.

The US–UK tax treaty allocates taxing rights between the two countries and provides relief mechanisms, including for pensions, dividends and government service. It works alongside the Foreign Tax Credit. However, the US saving clause preserves the right to tax its citizens, so the treaty rarely removes the US filing obligation.

No. UK National Insurance is generally treated as a social security contribution rather than an income tax, so it usually cannot be claimed as a Foreign Tax Credit. The US–UK Totalization Agreement instead determines which country you pay social security to, avoiding double social security charges.

This tool estimates the position on UK employment or self-employment income for an American resident in the UK. It does not model dividends, capital gains, rental income, pensions or the Net Investment Income Tax, all of which have their own cross-border rules. For a full picture, our advisers prepare a complete calculation.

US citizens must file annually based on citizenship, not residence, whenever income exceeds the filing threshold. Even when Foreign Tax Credits reduce your US tax to zero, the return, and often FBAR and FATCA forms, must still be filed. Failure to file can create penalties despite no tax being due.

The IRS accepts a consistent, reasonable exchange rate, such as the yearly average published by the US Treasury, or the spot rate on the date of each transaction. This calculator lets you set the rate so you can test different assumptions. Using a consistent method year to year is important.

Possibly. The US does not automatically recognise the tax-free growth of UK pensions, and employer contributions can be treated differently. The US–UK treaty offers relief for many pension arrangements, but the rules are intricate. This is one of the most common areas where cross-border returns go wrong.

The Net Investment Income Tax is a 3.8% US surtax on investment income above certain thresholds. Crucially, the Foreign Tax Credit cannot be used against it, so it can create a genuine double tax charge for higher-income Americans abroad with investment income. Planning around it is important for wealthier expats.

Yes. The US taxes based on citizenship while the UK taxes based on residence, so US citizens living in the UK are effectively subject to both systems at once. The treaty tie-breaker rules and reliefs coordinate the two, which is precisely why specialist cross-border advice matters.

It provides a reliable directional estimate for straightforward employment income. Real cross-border returns involve pensions, investments, currency timing, state taxes and the interaction of multiple forms. Treat the result as a guide, then let our specialists prepare the definitive figures.

No. Your UK return uses sterling and your US return uses US dollars. You convert UK figures to dollars for the US return using an acceptable exchange rate. Managing this conversion consistently across income, tax paid and credits is a key part of getting cross-border filings right.

The UK Self Assessment deadline is 31 January following the 5 April year end. US returns are due 15 April, with an automatic extension to 15 June for citizens abroad and a further extension available to 15 October. Coordinating both timelines avoids last-minute errors.

For most Americans in the UK, yes. The combination of two tax systems, currency conversion, pensions and investment rules makes DIY filing risky and often more expensive in missed reliefs. Specialist advice usually pays for itself while removing the stress and penalty risk.