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    TaxKilnUK tax guidance
    TaxKilnUK tax guidance

    Moving Abroad → UK IHT plus US estate tax

    UK IHT plus US Estate Tax Interaction, UK-USA Estate Tax Treaty 1978

    The UK-USA Estate Tax Treaty 1978 (separate from the income tax DTA) coordinates UK Inheritance Tax and US federal estate tax. US federal estate tax exemption is 13.99m USD for 2025, rising to roughly 15m USD for 2026 under the One Big Beautiful Bill Act (OBBBA, verify implementation), much higher than UK NRB 325k GBP plus RNRB up to 175k GBP. Twelve states plus DC have separate state-level estate taxes with much lower thresholds (NY 7.16m USD, MA 2m USD, OR 1m USD). The April 2025 UK reform replaced domicile-based IHT with the Long-Term Resident test, changing UK-side scope dramatically. The 1978 Estate Tax Treaty resolves potential double taxation via primary-taxing-rights rules and a credit mechanism.

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    Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact HMRC. Read our editorial scope →

    In plain English

    Estate tax (called Inheritance Tax in the UK) is the tax on what you leave when you die. Both the UK and the USA have it but the structures are different. The US federal exemption is very large: 13.99m USD per person in 2025, rising to roughly 15m USD in 2026 under recent legislation. The federal rate above the exemption is 40 percent. For most UK emigrants the federal exemption is well above their estate value, so federal estate tax is unlikely. The trap is state estate taxes. Twelve states plus DC have their own estate tax with much lower thresholds. New York 7.16m USD, Massachusetts 2m USD, Oregon 1m USD, Washington 2.193m USD. If you die a New York resident with a 5m USD estate you owe NY estate tax even though federal would not apply. The UK side changed dramatically in April 2025. Domicile was replaced with the Long-Term Resident (LTR) test for IHT purposes. LTR = UK-resident in 10 of the previous 20 tax years. LTR persons are subject to UK IHT on worldwide estate; non-LTR persons subject to UK IHT only on UK-situated assets. The 3 to 10 year IHT tail post-departure adds further nuance. See /moving-abroad/april-2025-iht-reform-ltr for full mechanics. Where both UK IHT and US estate tax apply to the same asset, the 1978 Estate Tax Treaty resolves the double tax via primary-taxing-rights rules (location of asset, domicile / treaty residence at death) and a credit mechanism. The treaty does NOT cover state-level estate taxes.

    How it works

    UK side, April 2025 LTR reform

    Finance Act 2025 replaced domicile with the Long-Term Resident (LTR) test for IHT purposes. LTR = UK-resident in at least 10 of the previous 20 tax years. LTR persons: subject to UK IHT on worldwide estate (broadly equivalent to the old UK-domiciled position). Non-LTR persons: subject to UK IHT only on UK-situs assets (broadly equivalent to old UK-non-domiciled position). IHT tail post-departure: LTR status persists for between 3 and 10 years after ceasing to be UK-resident, depending on how many years of UK residence preceded the departure (3 years tail for shorter residence; up to 10 years tail for very long residence). Full mechanics at /moving-abroad/april-2025-iht-reform-ltr.

    US federal estate tax

    US federal estate tax applies to worldwide estate of US-domiciled persons (citizens are deemed domiciled regardless of physical residence; non-citizens domiciled where they have a fixed plus permanent intent to remain). 2025 exemption: 13.99m USD per person (Rev. Proc. 2024-40). 2026: pending OBBBA implementation, expected ~15m USD (verify). Rate above exemption: 40 percent. Unlimited marital deduction for transfers to US-citizen spouse; transfers to non-US-citizen spouse are subject to estate tax with limited annual exclusion or qualified domestic trust (QDOT) structuring. Non-US-domiciled persons (typically non-citizens not US-resident): US estate tax applies only to US-situs assets (US real property, US business assets, US-issued stocks), with a much smaller exemption (60k USD under domestic law, increased under specific treaties).

    State estate taxes (the under-recognised trap)

    12 states plus DC levy estate tax separate from federal. Thresholds and rates 2025 (verify current): - Connecticut: 13.99m USD (matches federal), 12 percent rate - District of Columbia: 4.873m USD, up to 16 percent - Hawaii: 5.49m USD, up to 20 percent - Illinois: 4m USD, up to 16 percent - Maine: 7m USD, up to 12 percent - Maryland: 5m USD, up to 16 percent - Massachusetts: 2m USD, up to 16 percent - Minnesota: 3m USD, up to 16 percent - New York: 7.16m USD, up to 16 percent (with cliff effect above 105 percent of threshold) - Oregon: 1m USD, up to 16 percent - Rhode Island: 1.802m USD, up to 16 percent - Vermont: 5m USD, 16 percent flat - Washington: 2.193m USD, up to 20 percent State estate tax NOT covered by the UK-USA Estate Tax Treaty 1978. UK IHT paid generally not creditable against state estate tax (some state credit mechanisms may apply, fact-specific).

    UK-USA Estate Tax Treaty 1978, coordination mechanism

    The treaty resolves potential double tax through: 1. Primary-taxing-rights rules based on the deceased's treaty domicile at death (treaty has its own domicile concept, broadly aligned with UK domicile pre-April 2025; post-2025 alignment with LTR is interpretively uncertain). 2. Tie-breaker rules where dual-domicile (similar to income tax DTA Article 4). 3. Credit mechanism: the country with secondary taxing rights credits the tax paid in the primary country. 4. Specific provisions for jointly-owned property, UK-situs assets, US-situs assets. For a deceased UK-domiciled (or LTR) person with US-situs assets: UK IHT applies to worldwide estate, US federal estate tax applies to US-situs assets; US gives credit for UK IHT on US-situs assets (or vice versa per treaty). The treaty does NOT cover state estate tax. Where state estate tax applies (e.g. NY-resident-at-death with NY-situs assets), the state typically computes its tax based on the federal estate tax base without separate UK IHT credit, creating double tax that no treaty resolves.

    Who this applies to + key conditions

    Statute + manual references

    Primary: UK-USA Estate Tax Treaty 1978; IHTA 1984 plus Finance Act 2025 (LTR reform); IRC ss.2001-2058 (US federal estate tax); state estate tax statutes (per state)

    Related: IHTA 1984 s.6 plus s.272 (UK situs rules); Finance Act 2025 (Long-Term Resident test, replacing domicile for IHT); IRC s.2103 (US estate tax on non-resident aliens, US-situs only); IRC s.2001 plus Rev. Proc. 2024-40 (federal exemption)

    HMRC manual: HMRC IHTM (Inheritance Tax Manual) plus IRS Estate Tax pages

    Common mistakes + traps

    Worked example

    Robert, UK national, retired to Florida 2018, dies 2026 with a 4m USD estate (FL home 1.5m, US brokerage 2m, UK pension 0.5m equivalent)

    Robert was UK-resident until 2018, moved to Florida age 60, now age 68. He was UK-domiciled (pre-2025 rules) and continues as LTR under transitional rules for IHT tail purposes (more than 10 years UK residence pre-departure = 10-year tail). He has not formally established US domicile (no Green Card, no US citizenship application). Florida has no state estate tax.

    1. UK side: Robert remains LTR for IHT (10-year tail not yet expired; in this scenario he is at 8 years post-departure). UK IHT applies to worldwide estate of 4m USD equivalent (roughly 3.2m GBP). After NRB 325k GBP plus RNRB 175k GBP if FL home qualifies as 'main residence' for RNRB purposes (LITRG view is fact-dependent), IHT charge on excess. Estimated UK IHT: roughly 1.1m GBP (40 percent of approx 2.7m GBP above the combined NRB).
    2. US side, federal: Robert is not US-citizen, not Green Card holder. US domicile analysis is fact-based: 8 years in Florida, owns Florida home, has US ties. Likely treated as US-domiciled for federal estate tax purposes despite no Green Card. If US-domiciled, federal exemption 13.99m USD applies to worldwide estate of 4m USD = no federal estate tax.
    3. If treated as non-US-domiciled (alternative analysis): US federal estate tax applies to US-situs assets only (FL home 1.5m USD plus US brokerage 2m USD = 3.5m USD), with 60k USD domestic-law exemption, increased under treaty.
    4. US side, state: Florida has no estate tax. No state tax.
    5. Treaty coordination: UK-USA Estate Tax Treaty 1978 resolves any double tax. US estate tax (if any) on US-situs assets credits against UK IHT on those same assets (subject to credit limitation).
    6. Likely outcome: under US-domiciled analysis, UK IHT applies to worldwide; treaty credit eliminates any double tax. Net cost roughly 1.1m GBP UK IHT.
    7. Planning: had Robert formally established US domicile and used available federal exemption via lifetime giving (19k USD annual exclusion per donee 2025) plus structured timing of LTR tail (e.g. dying after 10-year tail expires), UK IHT exposure could have been managed down. Specialist UK-USA estate planning input warranted for estates above 1m USD given the complexity.

    Outcome: Robert's estate pays roughly 1.1m GBP UK IHT under LTR tail; no US federal tax under US-domiciled analysis; no Florida state estate tax. Total tax position is UK-driven. Had Robert chosen New York instead of Florida, NY state estate tax above 7.16m USD would not bind (estate below threshold), but for a wealthier emigrant New York vs Florida state-of-residence-at-death is a substantial planning lever.

    How this connects to the rest of the framework

    April 2025 IHT reform + LTR →

    UK IHT scope is determined by the LTR test post-April 2025; foundational for any UK-USA estate tax analysis.

    SRT plus Substantial Presence Test →

    US estate tax domicile concept (intent-based) differs from income tax residence; can persist beyond income tax non-residence.

    DTA mechanics plus saving clause →

    Income tax DTA and Estate Tax Treaty are separate instruments with different mechanics; do not conflate.

    Frequently asked questions

    What happens if I miss the Self Assessment deadline?+
    The Self Assessment deadline is 31 January (online filing) for the previous tax year. Miss it and HMRC apply an automatic £100 penalty. Beyond that: £10 per day from 3 months late (capped at £900), 5% of tax due at 6 months late, and another 5% at 12 months late, under Schedule 55 of the Taxes Management Act 1970. If you have a genuine reason (serious illness, bereavement, technical issue with HMRC's systems) you can appeal with evidence; HMRC accepts reasonable excuse appeals in most genuine cases.
    Do I need an accountant or can I file Self Assessment myself?+
    Legally you can file Self Assessment yourself via gov.uk for free, most simple sole-trader returns (single income source, basic expenses) are realistic to self-file. An accountant adds real value when: your trading profit is above £40,000 (extraction-strategy decisions matter), you have multiple income streams (PAYE + self-employment + property + dividends), you've crossed the £90,000 VAT threshold, you're considering incorporation, or you have an HMRC enquiry. Expect to pay £400-£1,500/year for a typical sole-trader accountant; the cost is itself a deductible expense.
    How do payments on account work?+
    When your Self Assessment tax bill exceeds £1,000 for the first time, HMRC requires payments on account toward NEXT year's tax. Half the current bill is due 31 January (alongside the current bill); the other half is due 31 July. So your first January after crossing the threshold can hit with a double-bill: last year's balance + first payment on account. Adjust via Form SA303 if you expect next year's income to drop substantially. Payments on account don't apply if more than 80% of your tax is collected via PAYE.
    What is US estate tax domicile and how does it differ from income tax residence?+
    US estate tax domicile is fact-based: physical presence in a place plus a fixed and present intention to remain indefinitely. It can persist after income tax residence ends and can apply before income tax residence begins. Indicia include US home ownership, US driver's licence, US voter registration, where personal effects are located, where family resides, where social and religious affiliations are based, and stated intent in legal documents. Green Card holding is a strong factor but not determinative. Income tax residence (Substantial Presence Test, Green Card) and estate tax domicile are independently analysed and can diverge.
    Does the 1978 Estate Tax Treaty give a higher US estate tax exemption for non-US-domiciled UK residents?+
    Yes. Under the treaty, a UK-domiciled / LTR person with US-situs assets gets a unified credit equivalent to a pro-rata share of the full US federal estate tax exemption, calculated as US-situs assets divided by worldwide estate, multiplied by the federal exemption. This is much more generous than the 60k USD domestic-law exemption available without the treaty.
    What happens to my UK pension on death for US estate tax purposes?+
    UK pension funds passing on death are not typically subject to UK IHT (within the pension wrapper) but are subject to UK income tax on the beneficiary if the deceased was over 75 (or income tax-free if under 75, subject to current UK pension death benefit rules and the LSDBA). For US estate tax purposes, foreign pension funds are includible in the gross estate of a US-domiciled decedent at fair market value. UK-USA Estate Tax Treaty does not modify this. US-domiciled UK-pension-holding emigrants should model the gross-up.
    How does the April 2025 UK LTR reform affect existing US-resident UK emigrants?+
    Existing UK emigrants who were UK-domiciled pre-April 2025 are caught by transitional rules. LTR status is determined by recent UK residence history (10 of 20 prior years). The IHT tail post-departure persists for 3 to 10 years depending on prior residence length. A long-term UK emigrant who left 15 years ago is likely outside LTR scope entirely now. A more recent emigrant (e.g. departed 2024) is likely still LTR for several years post-departure. Specialist UK-side input warranted for the transitional analysis. See /moving-abroad/april-2025-iht-reform-ltr for full mechanics.

    Free + regulated-body resources

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