US Expat Tax Services UK IHT and US Estate Tax Guide |
By US-UK Tax Advisors cross-border tax team · Last updated JUL 14, 2026
US Expat Tax Services UK IHT and US Estate Tax Guide | US Expat Tax Services: UK IHT and US Estate Tax Guide US Expat Tax Services on UK IHT and US Es...
Key Takeaways
- Covers us expat tax for US-UK cross-border taxpayers
- Applies to US persons with UK ties and UK residents with US income
- Highlights the filing, reporting and tax-treaty points to check
- Get personalised advice before acting on your own facts
US Expat Tax Services UK IHT and US Estate Tax Guide |
US Expat Tax Services: UK IHT and US Estate Tax Guide
US Expat Tax Services on UK IHT and US Estate Tax
US expat tax services for Americans living in the UK must address one of the most consequential tax interactions in cross-border planning — the interaction between UK Inheritance Tax and US estate tax on the same worldwide assets. From April 2025, the Finance Act 2025 brought the worldwide estates of long-term UK residents into the UK IHT net — meaning a US citizen who has been UK-resident for ten or more of the preceding twenty years now owes UK IHT at 40% on their global assets at death, in addition to any US estate tax on the same assets. Furthermore, the US-UK Estate and Gift Tax Treaty provides a proportional credit that prevents genuine double taxation — but the credit must be actively calculated and claimed, and the planning required to reduce the combined exposure must be implemented years before death rather than at the point of a terminal diagnosis. Additionally, the unified credit in the United States — currently approximately $13.61 million per person — means that most Americans do not owe US estate tax, making the UK IHT the dominant cross-border death tax concern for American expats in the UK. Consequently, understanding how the two systems interact is essential for planning territory for every American who has been a UK resident for several years.
How UK IHT Applies to US Citizens in the UK
The Long-Term Resident Threshold Under FA 2025
The Finance Act 2025 replaced the UK domicile concept with a residence-based system for IHT. Furthermore, a person is a long-term UK resident — and therefore subject to UK IHT on their worldwide estate — where they have been UK resident in ten or more of the preceding twenty tax years. Additionally, once the long-term resident threshold is crossed, the worldwide estate becomes subject to UK IHT at 40% above the nil-rate band of £325,000 (plus the residence nil-rate band of £175,000 where applicable). Consequently, a US citizen who has been UK-resident for ten continuous years first crosses the long-term resident threshold — and from that point, their US investment portfolio, US bank accounts, US real estate, and all other worldwide assets are part of the UK IHT taxable estate. The HMRC IHT guidance is at https://www.gov.uk/inheritance-tax.
How UK IHT Is Calculated on a US Citizen's Estate
The UK IHT calculation for a long-term UK resident US citizen includes all worldwide assets — UK property, UK investments, US property, US investments, overseas bank accounts, and beneficial interests in trusts. Furthermore, the nil-rate band of £325,000 is available to every UK-domiciled or long-term resident individual, reducing the taxable estate by that amount before IHT is applied at 40%. Additionally, the residence nil-rate band of up to £175,000 is available where the deceased owned a UK residential property that is left to direct descendants. Consequently, a US citizen with a total worldwide estate of £1.8 million — including a UK home, a UK investment account, and a US investment portfolio — faces UK IHT of approximately £520,000 after both nil-rate bands where no lifetime planning has been done. The HMRC nil-rate band guidance is at https://www.gov.uk/guidance/inheritance-tax-thresholds.
Gifts and the Seven-Year Rule
The UK IHT system allows lifetime gifts to reduce the taxable estate — provided the donor survives seven years after making the gift. Furthermore, outright gifts to individuals — known as Potentially Exempt Transfers — are fully outside the IHT net where the donor survives seven years from the gift date. Additionally, gifts into discretionary trusts — known as Chargeable Lifetime Transfers — are subject to a 20% IHT charge when they exceed the available nil-rate band. Consequently, a US citizen approaching or having recently crossed the long-term resident threshold who makes lifetime gifts to children or other beneficiaries begins the seven-year clock immediately — and the sooner the gifts are made, the sooner the clock starts running towards full IHT exemption. The HMRC gift exemption guidance is at https://www.gov.uk/gifts.
How the US Estate Tax Interacts With UK IHT
The US Unified Credit and Who Owes US Estate Tax
The US federal estate tax applies to the worldwide estate of US citizens — wherever they live and wherever they die. Furthermore, the US unified credit for 2025 is approximately $13.61 million per person — meaning estates below that threshold owe zero US estate tax. Additionally, for married US citizens, the unlimited marital deduction allows assets to pass to a US-citizen spouse entirely free of US estate tax at the first death. Consequently, most American expats in the UK do not owe US estate tax during their lifetimes — making the UK IHT the dominant death tax concern. However, Americans with large US investment portfolios, significant business interests, or extensive US real estate may have estates above the unified credit threshold, creating a dual IHT and estate tax exposure. The IRS estate tax guidance is at https://www.irs.gov/businesses/small-businesses-self-employed/estate-tax.
The US-UK Estate and Gift Tax Treaty
The US-UK Estate and Gift Tax Treaty prevents the same assets from being taxed at death by both countries through a proportional credit mechanism. Furthermore, the treaty allocates taxing rights based on the situs — the legal location — of each asset. It provides a credit in each country for tax paid to the other on overlapping assets. Additionally, UK IHT paid on UK-situs assets is creditable against US estate tax on the same assets where both taxes apply — and US estate tax paid on US-situs assets is creditable against UK IHT on the same assets. Consequently, for a US citizen whose estate is small enough to be below the US unified credit threshold — meaning zero US estate tax is due — the treaty credit for UK IHT against US estate tax produces no benefit, since there is no US estate tax to credit against. US expat tax services must model the treaty credit specifically for each client's asset mix and tax position. The full US-UK Estate Tax Treaty text is at https://www.gov.uk/government/publications/usa-tax-treaties.
Planning Before the Long-Term Resident Threshold
Step One: Confirm Your Year Count
The most urgent action for any US citizen approaching the ten-year UK residence threshold is confirming exactly which year the threshold will be crossed. Furthermore, the count is based on UK tax years of residence — not calendar years or continuous residence — meaning a year in which you were UK-resident for even part of the tax year typically counts as a full year. Additionally, any prior UK residence — including years before the current assignment — counts toward the twenty-year lookback period. Consequently, a US citizen who was UK-resident for two years in 2010-2012 and has been back since 2018 may be approaching or have crossed the ten-year threshold sooner than they realize. The HMRC SRT guidance is at https://www.gov.uk/government/publications/rdr3-statutory-residence-test-srt.
Step Two: Model the Combined IHT and US Estate Tax
Before implementing any lifetime planning, model the total combined IHT and US estate tax on the current worldwide estate — to quantify the exposure that planning is intended to reduce. Furthermore, the model must include all worldwide assets at current market values, apply the UK nil-rate bands, calculate the UK IHT, calculate the US estate tax where the estate exceeds the unified credit, and apply the treaty credit where both taxes apply. Additionally, the model should be stress-tested against a range of scenarios — assets appreciating by 20%, the unified credit reducing after 2025, and the sterling-dollar exchange rate moving — to confirm the planning strategies remain effective across different future conditions. Consequently, the combined IHT and estate tax model is the foundation of all US expat tax services advice on cross-border estate planning for American expats.
Step Three: Implement Lifetime Giving Before Threshold Crossing
The most effective IHT reduction strategy for a US citizen approaching the ten-year threshold is making significant lifetime gifts before the threshold is crossed — since gifts made before becoming a long-term resident are not subject to UK IHT at all. Furthermore, gifts of US assets — US investment portfolios, US real estate, minority interests in US businesses — made before the long-term resident threshold is crossed are entirely outside the UK IHT net, since the donor was not a long-term resident at the time of the gift. Additionally, for US citizens who have already crossed the threshold, outright gifts to children and other beneficiaries start the seven-year clock — with the gift becoming fully IHT-exempt after seven years. Consequently, the optimal lifetime giving program must be designed around the specific year in which the threshold was or will be crossed — making the year-count confirmation in Step One the prerequisite for all subsequent planning. The IRS gift tax guidance is at https://www.irs.gov/businesses/small-businesses-self-employed/frequently-asked-questions-on-gift-taxes.
Case Study: US Citizen in Year Nine of UK Residence
A US citizen engaged our team in year nine of UK residence — one year before crossing the long-term resident threshold — with a worldwide estate of approximately £2.4 million, including a UK home worth £750,000, a UK investment ISA worth £180,000, a US brokerage account worth approximately $890,000, and a US IRA worth approximately $420,000.
We modeled the combined tax position. Furthermore, the UK IHT on the worldwide estate after nil-rate bands would be approximately £620,000 — with the US estate well below the $13.61 million unified credit, meaning zero US estate tax. Additionally, since the US estate was below the estate tax threshold, the treaty credit provided no benefit. The full £620,000 UK IHT exposure was the planning target.
We recommended the following pre-threshold gifts. First, an immediate gift of the US brokerage account — approximately $890,000 — to the client's adult children before the threshold was crossed in April of the following year. Furthermore, this gift occurred entirely outside the UK IHT net — the donor was not yet a long-term resident — removing approximately £705,000 from the future UK taxable estate. Additionally, the gift started a seven-year clock from the date of gifting — with no UK IHT consequences even if the client died after becoming a long-term resident, since the gift was made before crossing the threshold. Consequently, the UK IHT exposure was reduced by approximately £282,000 from that single pre-threshold gift alone. The US IRA was not gifted — since IRA distributions to non-spouse beneficiaries are subject to US income tax, making the IRA poorly suited as a lifetime gift vehicle.
Common Mistakes in Cross-Border IHT Planning
Not Acting Before the Ten-Year Threshold
The most consequential mistake is waiting until after the ten-year threshold to begin IHT planning. Furthermore, gifts made before the threshold are entirely outside the UK IHT net — no seven-year clock, no taper relief, no IHT at all. Gifts made after the threshold start a seven-year clock. The correct approach requires identifying the threshold year in advance and implementing significant lifetime gifts — particularly of US assets — before the threshold is crossed. HMRC IHT guidance is at https://www.gov.uk/inheritance-tax.
Not Modelling the Treaty Credit for Dual-Tax Cases
Where a US citizen's estate exceeds both the UK nil-rate band and the US unified credit, both taxes apply — and the treaty credit can significantly reduce the combined tax. Furthermore, many UK estate planning advisers are not familiar with the US-UK Estate Tax Treaty and do not calculate the available credit. The correct approach requires a dual-qualified adviser who models both the UK IHT and the US estate tax simultaneously and calculates the treaty credit to confirm the net combined tax after relief.
Gifting IRA Assets as Lifetime Gifts
A common planning error for US citizens is gifting US IRA assets to children during their lifetime to reduce the IHT estate. Furthermore, an IRA cannot be directly gifted — the account must be liquidated first, triggering US income tax on the full withdrawal. Additionally, the after-tax proceeds can then be gifted. Still, the US income tax on the withdrawal significantly reduces the value of the gift compared with gifting non-IRA assets first. The correct approach requires a specific analysis of which assets are most efficiently gifted — generally non-IRA taxable brokerage assets before IRA assets. The IRS IRA guidance is at https://www.irs.gov/retirement-plans/individual-retirement-arrangements-iras.
How US-UK Tax Can Help
At US-UK Tax, our team of Enrolled Agents, Chartered Tax Advisers, and Certified Public Accountants provides specialist US expat tax services for Americans approaching or having crossed the UK long-term resident IHT threshold. Furthermore, we confirm the precise year count under the FA 2025 rules, model the combined UK IHT and US estate tax, calculate the treaty credit where both taxes apply, design the pre-threshold lifetime gift program, advise on trust structures, and coordinate the cross-border estate plan with the annual UK and US income tax compliance.
Contact our team today. Email hello@us-uktax.com, call 0333-8807974, or visit https://www.us-uktax.com/contact/.
Conclusion
The FA 2025 long-term resident rule makes UK IHT on worldwide assets a real and urgent concern for every US citizen who has been UK-resident for ten or more of the preceding twenty years. Furthermore, specialist US expat tax services that address both the UK IHT and the US estate tax simultaneously — and model the treaty credit where both apply — provide the foundation for effective cross-border estate planning. Moreover, the optimal planning window is before the ten-year threshold, when pre-threshold gifts of US assets are entirely outside the UK IHT net. Contact US-UK Tax at hello@us-uktax.com or call 0333-8807974 today.
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FAQs
Q: Does a US citizen in the UK owe UK IHT on their US assets?
A: Yes, once they become a long-term UK resident under FA 2025 — resident in ten or more of the preceding twenty tax years. From that point, UK IHT at 40% applies to the worldwide estate above the nil-rate band, including US investments, US property, and US bank accounts.
Q: Does the US-UK Estate Tax Treaty prevent double taxation?
A: Yes, through a proportional credit. UK IHT paid on UK-situs assets is creditable against US estate tax on the same assets, and vice versa. However, most American expats have estates below the $13.61 million US unified credit, meaning zero US estate tax — and therefore no credit to apply.
Q: What is the UK nil-rate band for IHT?
A: £325,000 per person in 2025-26. An additional residence nil-rate band of up to £175,000 applies where a UK residential property is left to direct descendants. An unused nil-rate band can be transferred to a surviving spouse, potentially sheltering £1 million from IHT.
Q: How do I reduce my UK IHT exposure as a US citizen?
A: The most effective strategies are making outright lifetime gifts — starting the seven-year clock — and making gifts of US assets before crossing the ten-year long-term resident threshold. Pre-threshold gifts of US assets are entirely outside the UK IHT net with no seven-year requirement.
Q: When exactly does the ten-year long-term resident threshold begin?
A: Under FA 2025, you become a long-term UK resident when you have been UK-resident in ten or more of the twenty tax years preceding the current year. Each UK tax year of residence — even partial — typically counts. Prior residence in the UK before the current assignment also counts toward the twenty-year lookback.
Q: Can I gift my US IRA to reduce my UK IHT estate?
A: Not directly. An IRA cannot be gifted — it must be liquidated first, triggering US income tax on the full withdrawal. The after-tax proceeds can then be gifted, but US income tax significantly reduces the effective value. Taxable brokerage assets should generally be gifted before IRA assets.
