UK vs US taxes guide for expats: Rates, filing, and double taxation

The biggest UK vs US tax difference is that the UK mainly taxes by residence, while the US taxes citizens and green card holders on worldwide income even when they live abroad. For 2025 US returns filed in 2026, expats may still need Form 1040, FBAR, Form 8938, and double-tax relief even after paying HMRC.

For Americans in the UK, American taxes vs UK taxes is not a choice between 2 systems – it is usually a coordination problem. Brits in the US face the reverse issue: UK residence can end, but UK-source income such as rent, pensions, or gains can still create UK filing obligations.

NOTE! Treaty relief can reduce double taxation, but it does not automatically remove filing duties in both countries.

UK vs US taxes: At a glance (2026)

UK vs US taxes differ most in 4 areas: who gets taxed, how payroll contributions work, how gains are treated, and when returns are due. For the 2025 US tax year filed in 2026, the US standard deduction is $15,750 for single filers and $31,500 for joint filers.

The key rule is simple: UK residence often controls UK tax, but US citizenship or green card status can keep Form 1040 in play even after 1 full year abroad.

 

NOTE! The American taxes vs UK comparison becomes misleading when it only compares income tax brackets. A US citizen in London may owe little or no US income tax after credits, but still may need to file Form 1040, FBAR by April 15 with automatic extension to October 15, and Form 8938 if foreign assets exceed the relevant threshold.

The following 3 takeaways matter most for expats comparing UK and US taxes:

• Filing is separate from owing tax. Paying HMRC does not automatically satisfy the IRS.
• Payroll taxes are not identical. National Insurance and the US Social Security/Medicare fund different systems and are coordinated through the US-UK Totalization Agreement.
• Credits usually matter more than brackets. Foreign tax credits often do more work than rate comparisons for US citizens living in the UK.

For England taxes vs US comparisons, use UK rates for England, Wales, and Northern Ireland, then check Scottish rates separately if you live in Scotland. Taxes in England vs US should not be treated as a full UK comparison because Scotland has different income tax bands.

Read our guide to citizenship-based taxation to better understand the rule that keeps US citizens in the IRS system.

Understanding the UK tax system

The UK tax system uses a tax year from April 6 to April 5, and residence is tested under the Statutory Residence Test. A person spending 183 or more days in the UK during a tax year is automatically a UK resident, but home, work, and tie rules can also apply.

UK residents normally pay UK tax on worldwide income and gains, while nonresidents usually pay UK tax only on UK-source income such as UK rent, wages, pensions, or certain gains. From April 6, 2025, the UK replaced the old remittance-basis non-dom regime with a 4-year foreign income and gains regime for qualifying new residents.

The following 4 residence checks help readers decide whether UK rates may apply before moving into the rate tables:

• 183-day test: Spending 183 or more days in the UK in a tax year usually makes you a UK resident.
• Home test: Having a UK home for at least 91 consecutive days, with at least 30 days of presence there, can create residence.
• Work test: Full-time UK work over a 365-day period can create residence.
• Sufficient ties test: Family, accommodation, work, 90-day, and country ties can make shorter UK stays taxable.

Are you a US expat in the UK? Let us get your IRS filing reports done right.

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Basic tax structure in the UK

The UK tax structure has at least 6 common layers for individuals: income tax, National Insurance, capital gains tax, VAT, inheritance tax, and local property taxes. For 2025/26, the standard Personal Allowance remains £12,570, but it phases out once income exceeds £100,000.

The following 6 UK tax categories affect expats most often:

• Income tax: Applies to employment, self-employment, pension, rental, and investment income after allowances.
• National Insurance: Applies to wages and self-employment profits, with separate employee, employer, and self-employed rules.
• Capital gains tax: Applies to taxable gains above the £3,000 annual exempt amount for 2025/26.
• VAT: Standard 20% consumption tax on most goods and services.
• Inheritance tax: Usually 40% above the nil-rate band, subject to exemptions and reliefs.
• Local property charges: Council Tax, SDLT, and local US property tax rules can all matter for cross-border homeowners.

Employees and self-employed people face different UK tax mechanics, even when the same £12,570 Personal Allowance applies.

 

Based on our client scenario at TFX: A salaried US citizen in Manchester earning £55,000 in 2025/26 may have UK PAYE withholding during the year, but still needs to report the same wages on a 2025 US Form 1040 filed in 2026. A self-employed US citizen with the same profit may also need to check whether the US-UK Totalization Agreement prevents double social contributions.

Businesses and contractors can review our tax tips for self-employed expats, and clergy with special self-employment issues should see our self-employment tax considerations for clergy abroad.

UK PAYE tax rates and thresholds

PAYE is the UK withholding system for employees, but withholding is not always the same as final liability. For 2025/26, England, Wales, and Northern Ireland use 20%, 40%, and 45% income tax rates after the £12,570 Personal Allowance.

For 2025/26, the main UK PAYE comparison starts with a £12,570 tax-free income and then moves through 20%, 40%, and 45% bands outside Scotland.

 

Scotland has separate income tax bands for employment, pension, and most other non-savings income. For 2025/26, Scottish rates range from 19% starter rate to 48% top rate, while savings and dividends follow UK-wide rules.

For 2025/26, Scotland’s income tax rates start at 19% after the Personal Allowance and reach 48% above £125,140.

 

Based on our client scenario at TFX: A US citizen employed in England with a £55,000 2025/26 salary has £12,570 covered by the Personal Allowance, £37,700 taxed at 20%, and £4,730 taxed at 40%. That produces an income tax of about £9,432 before National Insurance, tax code adjustments, student loans, or other reliefs.

PAYE feels similar to US withholding, but it does not replace US reporting. Review our Form W-4 guide for US withholding and our Form W-2 guide if you have US payroll documents alongside UK payslips.

UK vs US income tax rate comparison

A UK vs US income tax comparison should start with taxable income, not gross salary. For the 2025 US tax year filed in 2026, federal rates run from 10% to 37%, while England, Wales, and Northern Ireland use 20%, 40%, and 45% after allowances.

The UK tax rate vs US comparison is clearest when the table separates headline rates from deductions and payroll taxes.

 

The Income tax UK vs US comparison often shows higher UK headline rates for mid-to-high earners, but the US standard deduction and filing status rules change the result. For 2025, the standard deduction is $15,750 for single filers and $31,500 for married filing jointly after the OBBB update.

The tax rate in the UK vs the US is only one part of actual liability because the US may add state income tax, while the UK adds National Insurance. The income tax in the UK vs the US result also depends on whether foreign tax credits offset US tax on the same UK-taxed income.

Which country has higher income taxes? For middle-income employees in England, UK income tax plus National Insurance can be higher than US federal tax alone. For high earners in California or New York, the US federal plus state tax can exceed UK headline rates. For expats, the average effective rate usually matters more than the top marginal rate.

What about average income taxes US vs UK? Average effective tax compares total tax paid against total income after deductions, credits, and payroll charges. A US citizen in London may have a high UK effective rate but a low final US income tax bill after Form 1116 foreign tax credits.

 

 

Read our guide on US filing status with a foreign spouse because married filing jointly, married filing separately, and head of household can change the US result.

UK National Insurance vs US Social Security and Medicare

National Insurance and US Social Security/Medicare are payroll contribution systems, not pure income taxes. For 2025, US Social Security applies at 6.2% each for employee and employer up to $176,100, while Medicare applies at 1.45% each with no wage cap.

Payroll tax comparisons become misleading unless they separate employee rates, employer rates, wage ceilings, and the benefit system being funded.

 

For expats: UK vs US comparisons often overstate or understate tax burden by mixing income tax with payroll contributions. The US-UK Totalization Agreement is designed to prevent dual Social Security coverage for the same work, but workers may need a certificate of coverage to prove the correct system applies.

The following 4 people should verify payroll coverage before filing:

• A US citizen employed by a US company while working in the UK.
• A US citizen hired locally by a UK employer.
• A self-employed American contractor living in the UK.
• A UK citizen temporarily assigned to a US employer.

 

 

Review our Social Security for expats Q&A, and use our guide to certificates of coverage and A1-style documentation when cross-border payroll creates duplicate contribution risk.

Solve your tax question – ask professionals

A cross-border tax review is most useful when 3 issues overlap: foreign tax credit versus FEIE coordination, treaty residency or tie-breaker questions, and filing obligations in both countries. For 2025 returns, a missed Form 1116, Form 2555, FBAR, or Form 8938 can change the result even when no US tax is due.

The following 5 situations deserve professional review before filing:

• You paid UK tax on wages, but you are unsure whether to claim FTC, FEIE, or both on separate income.
• You moved during 2025 or 2025/26 and may have split-year UK treatment.
• You have a UK pension, ISA, brokerage account, or limited company.
• Your foreign financial accounts exceeded $10,000 at any time during 2025.
• Your foreign financial assets may exceed Form 8938 thresholds.

TFX can help organize the US side, flag cross-border issues, and reduce back-and-forth with the IRS. Read our guide on when to hire an expat tax professional for situations where a DIY return may miss treaty or reporting details.

The following 3-step process keeps the next move simple:

1. Share where you lived, earned income, and paid tax during 2025.
2. Upload UK payslips, P60/P45, Self Assessment records, bank balances, and investment statements.
3. Get a US filing plan that coordinates income, credits, disclosures, and deadlines.

With 20+ years of experience in US expatriate tax services, we can simplify your expat experience in the UK.

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UK vs US corporate taxation

UK vs US corporate taxation differs in rate structure, entity classification, and shareholder-level treatment. For 2025/26, UK corporation tax is generally 19% for small profits up to £50,000 and 25% above £250,000; the US federal C corporation rate is generally 21%.

Corporate rate comparisons work best when the table separates company tax, owner tax, and entity classification.

 

A UK limited company owned by a US citizen can create US international information reporting even if all business activity is in the UK. See our guide to choosing business structures abroad as a US expat, and review Form 1120-F filing issues if a foreign corporation has US-source or US-connected activity.

Corporate tax rates in the UK (2025/26)

UK corporation tax for 2025/26 generally uses 3 bands: 19% small profits rate, 25% main rate, and marginal relief between £50,000 and £250,000. These thresholds can be reduced when a company has associated companies, so owner-managed groups need careful review.

For 2025/26, UK companies generally move from 19% to 25% once profits rise from £50,000 to above £250,000.

 

Based on our client scenario at TFX: A UK company with £40,000 of taxable profits generally pays £7,600 at the 19% small profits rate. A company with £300,000 of taxable profits generally starts with £75,000 at the 25% main rate before credits, reliefs, or associated-company adjustments.

US owners of UK companies should also review our guide to offshore corporation benefits and disadvantages before assuming a UK company reduces US reporting.

Corporate tax system in the US (2025/26)

The US federal corporate tax rate for C corporations is generally 21%, but the owner’s final tax result depends on entity type. An LLC may be disregarded, taxed as a partnership, or elect corporate classification using Form 8832, while an S corporation passes items through to eligible shareholders.

The following 3 US entity examples show why structure matters:

• C corporation: Pays corporate tax at the entity level, and dividends may be taxed again to shareholders.
• S corporation: Passes income, losses, deductions, and credits to shareholders, but eligibility restrictions apply.
• Disregarded LLC: Usually reports business income directly on the owner’s US return unless another election applies.

Read our guide to forming a US LLC as a nonresident, and see our Form 8832 entity classification election guide before matching UK and US entity treatment.

UK vs US capital gains taxes

UK vs US capital gains taxes differ in holding-period rules, annual allowances, and exchange-rate effects. For 2025 US returns, long-term gains are generally taxed at 0%, 15%, or 20%; in the UK, the 2025/26 annual exempt amount is £3,000, and most rates are 18% or 24%.

The practical comparison is that the US rewards holding assets over 1 year, while the UK starts with a £3,000 annual exempt amount and then applies 18% or 24% rates.

 

Based on our client scenario at TFX: A US citizen in London sells UK shares with a £23,000 gain in 2025/26. The UK may allow a £3,000 annual exempt amount, leaving £20,000 taxable, while the US return must translate the purchase price and sale price into USD using appropriate exchange-rate records.

Read our guide on capital gains tax for expats, and review our guide to capital gains tax on the sale of a primary residence in the US and abroad before selling a home.

US capital gains tax rates (2025)

The US capital gains tax for 2025 depends on whether the asset is short-term or long-term. Long-term gains use 0%, 15%, or 20% thresholds; short-term gains are taxed at ordinary income rates up to 37%.

For 2025, the 0% long-term capital gains bracket ends at $48,350 for single filers and $96,700 for married joint filers.

 

High-income taxpayers may also owe the 3.8% Net Investment Income Tax when modified adjusted gross income exceeds $200,000 for single filers or $250,000 for married filing jointly.

Based on our client scenario at TFX: A single US filer with $100,000 of taxable income, including a $20,000 long-term gain, generally falls into the 15% long-term capital gains range. If the same filer has a modified adjusted gross income above $200,000, NIIT may also apply to investment income. Review our foreign tax credit guide if the UK also taxes the same gain.

UK capital gains tax rates (tax year 2025/26)

UK capital gains tax for 2025/26 generally gives individuals a £3,000 annual exempt amount before taxable gains are charged. Most gains are taxed at 18% for basic-rate taxpayers and 24% for higher or additional-rate taxpayers, with special reliefs and rules for certain business gains.

For 2025/26, the UK annual exempt amount is £3,000, and most taxable gains fall into 18% or 24% rates.

 

Based on our client scenario at TFX: A basic-rate UK taxpayer sells shares with a £13,000 gain in 2025/26. After the £3,000 annual exempt amount, £10,000 remains taxable, and a basic-rate taxpayer may pay about £1,800 at 18% if the gain stays within the basic-rate band.

A US citizen selling UK property should also check US reporting and exchange-rate effects. Read our guide to capital gains tax on foreign property, and see our FIRPTA guide if US real property is involved.

UK vs US VAT rates

UK VAT and US sales tax are both consumption taxes, but they work differently. The UK standard VAT rate is 20%, with reduced 5% and zero-rated 0% categories; the US has no federal VAT and relies on state and local sales tax systems.

The key distinction is that UK VAT is usually built into the displayed price, while US sales tax is commonly added at checkout.

 

A tourist buying goods in London may feel VAT because it is embedded in the shelf price. A business owner may care more about whether VAT is recoverable, while a US buyer may see sales tax separately added on the receipt.

See our discussion of sales tax updates for US taxpayers, and review our guide to states without income tax when comparing US state-level tax burdens.

VAT system in the UK

The UK VAT system uses 3 main rates: 20% standard, 5% reduced, and 0% zero rate. Some transactions are exempt or outside the scope, and VAT-registered businesses generally account to HMRC for output tax and may recover input VAT on qualifying business costs.

The following 4 VAT categories matter most in everyday UK tax comparisons:

• 20% standard rate: Most goods and services.
• 5% reduced rate: Certain items, such as children’s car seats and home energy.
• 0% zero rate: Some goods, such as most food and children’s clothing.
• Exempt items: Certain financial, property, health, education, and postal services.

Based on our client scenario at TFX: A US citizen renting out a UK property may focus less on VAT for personal shopping and more on whether rental income, property expenses, and mortgage interest are reported correctly in both countries.

Review our foreign property tax guide, and see our foreign rental income tax guide if a UK rental property appears on a US return.

Sales tax structure in the US

US sales tax is imposed by states and localities, not as a single federal tax. Rates, exemptions, filing duties, and taxable items differ by jurisdiction, so a 2025 receipt in New York, Texas, or Oregon can show very different sales tax results.

The following 3 facts keep US sales tax separate from VAT:

• No federal VAT: The IRS does not administer a national retail sales tax.
• Jurisdiction variation: State, county, city, and special district rules can apply.
• Checkout calculation: US prices often show sales tax as a separate line.

Based on our client scenario at TFX: A $100 purchase in a 7.5% combined sales tax area would show $7.50 of sales tax and a $107.50 total. In the UK, a £100 consumer price usually already includes VAT unless the seller displays business-to-business pricing differently.

Estate and inheritance taxes

The UK generally uses inheritance tax on the estate, while the US uses a federal estate tax above a high exemption. UK inheritance tax commonly starts with a £325,000 nil-rate band; the US federal estate tax exemption is $13.99 million for 2025 deaths and $15 million for 2026 deaths.

For cross-border families, the practical issue is not just the 40% headline rate – it is which country can tax which assets and which exemption applies.

 

Cross-border families should confirm treaty, domicile/residence, and asset-situs rules before transferring assets. A UK home, US brokerage account, UK pension, IRA, or jointly owned property can create different reporting and tax results in each country.

Read our guide to estate taxes for expatriates, and review our foreign inheritance tax guide before assuming an inheritance is tax-free in the US.

Inheritance tax in the UK

UK inheritance tax usually starts with a £325,000 nil-rate band and a possible £175,000 residence nil-rate band when a qualifying home passes to direct descendants. The standard rate is often 40% on the taxable estate above available thresholds, subject to spouse, charity, business, and agricultural reliefs.

A UK estate may pass up to £500,000 free of inheritance tax when the £325,000 nil-rate band and £175,000 residence nil-rate band both apply.

 

Based on our client scenario at TFX: A UK estate worth £700,000 with a qualifying home and investments may use a £325,000 nil-rate band and up to £175,000 residence nil-rate band. If both apply fully, £200,000 remains exposed to UK inheritance tax before other reliefs.

The following 5 documents help families avoid delays:

• Will and codicils.
• Probate or estate inventory.
• Property valuations.
• Bank, brokerage, pension, and retirement account statements.
• Records of gifts made within 7 years.

For inherited US retirement accounts, see our guide to inherited IRA distribution rules.

Estate taxes in the US

US federal estate tax applies only above a high exemption for US citizens and domiciliaries, but nonresident noncitizens face a much lower filing threshold for US-situs assets. The IRS lists $13.99 million for 2025 deaths, $15 million for 2026 deaths, and a $60,000 Form 706-NA threshold for nonresident noncitizens.

Check out our guide to the federal estate tax for foreigners investing in the United States if a non-US person holds US assets.

US estate tax exposure can be minimal for a US citizen under $13.99 million in 2025, but a nonresident noncitizen with more than $60,000 of US-situs assets may need Form 706-NA review.

 

Based on our client scenario at TFX: A US citizen dying in 2025 with a $4 million worldwide estate may be below the federal estate tax filing threshold. A UK resident who is not a US citizen but owns $250,000 of US stocks may need a US estate tax review because US-situs asset rules are different.

UK vs US property taxes

UK vs US property taxes differ because the UK leans more on Council Tax and purchase taxes, while the US relies heavily on the annual local property tax. In England and Northern Ireland, SDLT residential rates start at 0% up to £125,000 from April 1, 2025.

The main comparison is upfront versus annual cost: UK buyers may face SDLT at purchase, while US owners often face annual local property tax based on assessed value.

 

Based on our client scenario at TFX: A US citizen living in a London primary residence may pay Council Tax locally and still report a later sale on a US return. If the same person rents out a UK flat, both UK rental reporting and US Schedule E reporting may apply.

The following 3 surprises catch property-owning expats:

• A UK primary residence may still need US gain calculations in USD.
• US mortgage interest rules do not always match UK tax relief rules.
• UK Council Tax is not the same as US property tax for deduction and reporting purposes.

Review our foreign property tax guide, and see our guide to taxes and loan interest deductibility.

Council tax and other property taxes in the United Kingdom

Council Tax is a local UK charge based on property valuation bands and local authority rates. In England, homes are placed in bands A to H based on April 1, 1991, values, and the person liable is usually the resident owner, tenant, or another responsible adult.

Council Tax is a recurring local bill, not a purchase tax, and it should be separated from SDLT and business rates.

 

The following 3 related costs should be reviewed separately from Council Tax:

• SDLT on purchase.
• Service charges, ground rent, or building maintenance.
• UK tax reporting for rental income.

Property owners can review our guide to property ownership structures and US expat taxes.

Stamp duty land tax

Stamp Duty Land Tax applies to many property purchases in England and Northern Ireland, with rates depending on price, buyer status, and property type. From April 1, 2025, standard residential rates start at 0% up to £125,000 and rise to 12% above £1.5 million.

For standard residential purchases from April 1, 2025, SDLT starts at 0% up to £125,000 and reaches 12% above £1.5 million before surcharges.

 

Based on our client scenario at TFX: A buyer purchasing a £295,000 home in England after April 1, 2025 pays 0% on the first £125,000, 2% on the next £125,000, and 5% on the final £45,000. Total SDLT is £4,750 before any surcharge.

Additional dwellings can face a 5% surcharge from October 31, 2024, and non-UK resident buyers can face a 2% surcharge on top of ordinary SDLT rates.

NOTE! Buying costs are not annual ownership taxes. SDLT is triggered by a purchase; Council Tax and US property tax are recurring ownership or occupancy costs.

Property tax system in the USA

US property tax is state and local, so there is no single federal property tax rate. Counties, cities, school districts, and other local authorities may assess property value and apply local millage or tax rates, while federal rules mainly affect possible deductibility.

US property tax is annual and local, while federal tax rules mainly affect whether and how property taxes or mortgage interest appear on a federal return.

 

Based on our client scenario at TFX: A US homeowner whose property is reassessed after purchase may see annual property tax rise even if income has not changed. A US expat renting that home while living in the UK may also need rental income and expense reporting.

Tax benefits and credits

The US system leans heavily on deductions and credits, while the UK relies more on allowances, reliefs, and source withholding. For 2025 US returns filed in 2026, the updated standard deduction is $15,750 single and $31,500 married filing jointly, and some OBBB changes may affect eligible taxpayers.

The following 5 expat-friendly US tax items often matter most:

• Foreign tax credit on Form 1116.
• Foreign earned income exclusion on Form 2555, up to $130,000 for 2025.
• Standard deduction or itemized deductions.
• Child Tax Credit, increased to $2,200 per eligible child under updated 2025 rules.
• Education credits and retirement-related deductions where eligibility requirements are met.

Relief type matters because some items reduce income, while others reduce tax dollar for dollar.

US tax deductions and credits

US deductions reduce taxable income, while US credits reduce tax owed. For 2025 returns, expats should check the $130,000 FEIE limit, and any eligible child, education, retirement, or foreign tax credit items.

The biggest expat distinction is that deductions reduce income, while credits reduce tax – and the foreign tax credit can directly offset US tax on foreign-taxed income.

 

Based on our client scenario at TFX: A single US filer in the UK with modest deductions may use the $15,750 standard deduction for 2025 rather than itemizing. A higher-income filer who paid UK income tax may still need Form 1116 because the standard deduction does not replace foreign tax credit calculations.

The following 3 benefit categories should be checked before filing:

• Education-related credits, including the Lifetime Learning Credit.
• Child-related credits, including Child Tax Credit eligibility.
• Retirement-related deductions or exclusions, especially where a UK pension is involved.

For higher education expenses, review our guide to education tax credits and the Lifetime Learning Credit.

How to avoid double taxation between the UK and the US

US-UK double taxation is usually reduced through foreign tax credits, the FEIE, treaty rules, and payroll coordination. For 2025, the FEIE can exclude up to $130,000 of qualifying foreign earned income, but it cannot be claimed on the same income used for a foreign tax credit.

Foreign tax credits usually fit UK-taxed wages, dividends, rental income, and gains because UK tax can be high enough to offset US tax. The FEIE only applies to earned income, so it does not shelter dividends, pensions, capital gains, or rental profits.

The following 5-step relief flow helps decide what to review first:

1. Identify the income type: wages, self-employment, dividends, pensions, rent, or gains.
2. Confirm which country has primary taxing rights under domestic law and treaty rules.
3. Check whether the income is earned income eligible for Form 2555.
4. Calculate foreign tax credits on Form 1116 for qualifying UK income tax.
5. Review treaty disclosure, FBAR, FATCA, and Totalization Agreement requirements separately.

NOTE! Do not claim both the FEIE and FTC on the same income. A common 2025 filing mistake is excluding UK wages on Form 2555 and also using the same UK tax on Form 1116, which can distort the return and create IRS correspondence.

Based on our client scenario at TFX: A US citizen resident in the UK earns £90,000 in 2025/26 and pays UK income tax through PAYE. On the US return, the income is reported in USD; then Form 1116 may reduce US tax using UK tax paid, while Form 2555 may be considered only for qualifying earned income and only where it produces a better coordinated result.

Read our guide to double taxation and ways to avoid it, and also, the official US-UK treaty documents when pensions, dividends, or residency tie-breakers are involved.

 

UK vs US tax filing process comparison

UK vs US tax filing differs because the UK often collects employee tax through PAYE, while the US generally requires a return when income, filing status, age, or other thresholds trigger filing. For 2025 returns, the US deadline is April 15, 2026, with an automatic June 15 expat filing extension.

The filing comparison turns on whether a return is required, which forms apply, and whether an extension only extends filing time or also affects payment.

 

The following 4-step flow helps expats decide whether both countries may need attention:

1. Were you a US citizen, green card holder, or US resident alien during 2025?
2. Were you a UK resident or did you have UK-source income during 2025/26?
3. Did foreign accounts exceed $10,000, or foreign financial assets exceed Form 8938 thresholds?
4. Did treaty, payroll, pension, rental, or business income create a separate disclosure?

Records matter because both countries may need different tax-year calendars and currency translation. Read our guide to foreign country tax filing deadlines, and use our expat IRS tax form checklist before filing.

Tax filing in the UK

UK Self Assessment for 2025/26 opens after April 5, 2026, with key deadlines on October 5, 2026, October 31, 2026, and January 31, 2027. PAYE employees may not need to file, but self-employed people, landlords, and higher-income or complex taxpayers often do.

The following 4-date UK timeline applies to many 2025/26 Self Assessment cases:

• April 6, 2026: Earliest start for filing a 2025/26 return.
• October 5, 2026: Deadline to tell HMRC if you need to complete a return for the first time or after reactivation.
• October 31, 2026: Paper return deadline.
• January 31, 2027: Online filing and balancing payment deadline.

The following 5 triggers commonly create a UK Self Assessment filing need:

• Self-employment or partnership income.
• UK rental income.
• Significant investment income or gains.
• High income with Child Benefit charge exposure.
• Claiming treaty relief, residence positions, or foreign income/gains relief.

Keep tax records long enough for both systems. Use our guide to preserving tax and financial records, and review our guide to filing for a tax extension if the US side needs more time.

Tax return process in the US

The US tax return process starts with whether a return is required, not with citizenship alone. For 2025, Form 1040 is due April 15, 2026; US citizens and resident aliens abroad may receive an automatic 2-month extension to June 15, but interest can apply after April 15 if tax is unpaid.

The following 6-step US filing checklist applies to many Americans in the UK:

1. Confirm filing requirement using income, filing status, age, and special forms.
2. Convert UK income and tax payments into USD.
3. Choose Form 1116, Form 2555, or both for different income categories when allowed.
4. Add foreign account and asset forms such as FBAR or Form 8938 when thresholds are met.
5. E-file where available or paper-file when forms require it.
6. Pay any 2025 US balance due as early as possible to reduce interest.

Before you file. Gather 8 records before preparing a 2025 US return: passport travel days, UK payslips, P60/P45, Self Assessment records, HMRC tax paid, bank maximum balances, investment statements, and pension/ISA documents.

FBAR is required when aggregate foreign financial accounts exceed $10,000 at any time during the calendar year, and Form 8938 thresholds for taxpayers living abroad can start at more than $200,000 on the last day of the year for unmarried filers.

Review our US tax forms for expats, and our detailed guide to the Foreign Bank Account Report.

What UK-specific tax traps catch Americans?

Americans in the UK often get caught by 4 issues: UK residence surprises, pension reporting, foreign financial accounts, and mismatched treatment of savings or investments. For 2025, a UK ISA can be tax-efficient in the UK but still reportable and potentially taxable in the US.

The following 4 common mistakes need early review:

• Common mistake: Assuming HMRC filing replaces Form 1040.
  How to avoid it: Treat US filing as a separate annual process for citizens and green card holders.
• Common mistake: Ignoring UK pension reporting.
  How to avoid it: Check treaty treatment, Form 8938, FBAR, and any employer or trust reporting questions before contributions or withdrawals.
• Common mistake: Treating a UK ISA like a US Roth IRA.
  How to avoid it: Review US tax treatment of interest, dividends, funds, and PFIC exposure.
• Common mistake: Forgetting exchange-rate gains on mortgages, investments, or property sales.
  How to avoid it: Track USD basis and proceeds from the purchase date through sale or repayment.

Based on our client scenario at TFX: A US citizen in Bristol holds a UK pension, an ISA, and a UK brokerage account. HMRC may treat the ISA favorably, but the US return may still need income reporting, FBAR, Form 8938, and possible PFIC review for non-US funds.

The following 3-position checklist helps identify when to review FBAR, FATCA, and treaty positions:

• Foreign account balances exceeded $10,000 at any point in 2025.
• Specified foreign financial assets exceeded Form 8938 thresholds.
• Pension, treaty, or residence facts affect who taxes the income first.

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