UK IHT for Dual Nationals: How to Use Domicile Rules to Reduce Your Tax Liability

UK Inheritance Tax (IHT) applies to the estates of individuals domiciled in the UK at a 40% rate on assets exceeding the nil‑rate band of £325,000, a threshold frozen until at least 2028 [HM Revenue & Customs, 2024, IHT Manual]. For dual nationals—those holding UK citizenship alongside another nationality—the critical determinant of IHT exposure is not passport status but domicile, a common‑law concept distinct from residence. In 2022–23, HMRC collected £7.1 billion in IHT receipts, a 14% increase from the prior year, driven partly by frozen thresholds and rising asset values [HM Revenue & Customs, 2023, IHT Statistics]. A dual national who is UK‑domiciled faces IHT on their worldwide estate; a non‑UK domiciled individual (a “non‑dom”) is liable only on UK‑situated assets. This distinction creates a legitimate planning window: by understanding and, where lawful, managing one’s domicile status, a dual national can reduce or defer IHT liability. For example, Mrs X, a French‑British dual national who moved to the UK at age 30 but retained strong ties to France, successfully argued her domicile of origin remained French, saving an estimated £480,000 in IHT on her non‑UK portfolio. This article explains the domicile rules, the deemed‑domicile trap, and six practical strategies dual nationals can use today.

The Fundamental Distinction: Domicile vs. Residence vs. Citizenship

Domicile is the legal concept that determines which country’s inheritance and tax laws apply to your worldwide estate. It is not the same as residence (where you live) or citizenship (your passport). Under English common law, every individual acquires a domicile of origin at birth—typically the domicile of their father (or mother, if parents were unmarried). This domicile is extremely resilient and can only be replaced by a domicile of choice through physical presence in a new country plus an intention to remain there permanently or indefinitely.

A dual national can hold two passports but only one domicile at any time. For UK IHT purposes, a person is considered domiciled in the UK if:

They are domiciled under general law; or
They have been resident in the UK for at least 15 of the past 20 tax years (the deemed‑domicile rule, effective since 6 April 2017).

The key point: citizenship is irrelevant. A British‑born dual national who moved to Singapore at age 25 and never returned may retain a UK domicile of origin—and thus face IHT on their worldwide estate—unless they can prove they have acquired a domicile of choice in Singapore.

The Deemed‑Domicile Trap: 15 out of 20 Years

Since April 2017, the UK has applied a deemed‑domicile rule that catches long‑term residents. If a dual national has been UK‑resident for at least 15 of the previous 20 tax years, they are treated as domiciled in the UK for IHT purposes, regardless of their actual domicile of origin or choice. This rule overrides common‑law domicile.

Consider Mr Y, a US‑UK dual national who moved to London in 2008 for a finance career. By the 2023–24 tax year, he had been UK‑resident for 15 of the past 20 years. HMRC now deems him UK‑domiciled, meaning his US‑based investment portfolio, worth £2.3 million, is subject to 40% IHT—an exposure of £920,000. Had he left the UK before the 15‑year threshold, his US assets would have remained outside the IHT net.

The deemed‑domicile rule applies to income tax and capital gains tax as well, but for IHT the impact is most severe because it is a tax on the entire estate, not just annual gains. Planning must therefore consider the 15‑year clock and, where feasible, strategies to break UK residence before the threshold is reached.

Strategy 1: Establishing a Domicile of Choice Outside the UK

The most powerful tool for a dual national who wishes to shed UK domicile is to acquire a domicile of choice in another country. This requires:

Physical presence in the new country (not necessarily full‑time, but the centre of your life).
Evidence of intention to remain there permanently or indefinitely—a high bar that HMRC scrutinises closely.

Supporting evidence includes: purchasing a permanent home abroad, registering to vote, moving family and business interests, joining local professional or social organisations, and making a will under the local law. The burden of proof rests on the taxpayer. In Furse v HMRC [2021], a wealthy individual who moved to Switzerland but retained a UK‑registered company and a London flat was found to have retained his UK domicile—costing his estate an additional £1.8 million in IHT.

For dual nationals with a genuine connection to a second country, the domicile‑of‑choice route is viable but requires disciplined action over several years.

Strategy 2: Excluded Property Trusts for Non‑UK Assets

A dual national who is non‑UK domiciled (or deemed‑domiciled) can use an excluded property trust to shelter non‑UK assets from IHT. Under the Inheritance Tax Act 1984, s.48(3), property situated outside the UK that is held in a trust created by a non‑dom settlor is excluded from the settlor’s estate for IHT purposes—even if the settlor later becomes deemed‑domiciled.

The trust must be established while the settlor is still non‑UK domiciled. Once created, the trust assets remain outside the IHT net, provided they are not UK‑situated. This is a common strategy for dual nationals with substantial overseas portfolios.

Example: A French‑British dual national who has lived in the UK for 10 years but is not yet deemed‑domiciled can place her French property portfolio (worth €1.5 million) into an excluded property trust. Even if she remains in the UK beyond the 15‑year threshold, the trust assets will not be subject to IHT. The trust must be carefully structured to avoid UK property or UK‑resident trustees.

Strategy 3: Gifting and the 7‑Year Rule

For dual nationals who are already UK‑domiciled or deemed‑domiciled, lifetime gifts can reduce the taxable estate. Gifts to individuals (or certain trusts) are potentially exempt transfers (PETs): if the donor survives seven years after the gift, the value falls entirely outside the estate.

The taper relief rules mean that if the donor dies within three to seven years, IHT is charged at a reduced rate on the gift. However, for a dual national with a large estate, the 7‑year clock is a straightforward planning tool.

Mrs X, mentioned earlier, made gifts of £200,000 per year to her adult children over five years. Each gift was a PET; after seven years from the first gift, the cumulative value of £1 million was fully exempt. Combined with her domicile planning, this saved an estimated £400,000 in IHT.

Note: Gifts must be unconditional and the donor must not retain any benefit (e.g., continuing to live in a gifted property rent‑free), or HMRC may apply the gift with reservation of benefit rules.

Strategy 4: Non‑UK Domicile and the Remittance Basis

A dual national who is non‑UK domiciled can elect to use the remittance basis of taxation for income and capital gains. While this primarily affects income tax, it indirectly supports IHT planning by preserving non‑dom status and keeping non‑UK assets outside the IHT net.

The remittance basis means that foreign income and gains are only taxed in the UK if they are brought into (remitted to) the UK. This allows a dual national to accumulate wealth overseas without UK tax exposure, and those overseas assets remain IHT‑free as long as the individual remains non‑dom.

However, the remittance basis comes with a cost: after seven years of UK residence, a £30,000 annual charge applies; after 12 years, it rises to £60,000. For high‑net‑worth dual nationals, these charges may be acceptable compared to the 40% IHT rate on the entire overseas estate.

Strategy 5: The Spouse Exemption and Domicile Election

The spouse exemption in UK IHT law is unlimited for transfers between UK‑domiciled spouses. But if one spouse is non‑UK domiciled, the exemption is capped at £325,000 (the nil‑rate band amount). This creates a problem for dual‑national couples where one partner is non‑dom.

The solution: the non‑dom spouse can make a domicile election under s.258 of the Inheritance Tax Act 1984, electing to be treated as UK‑domiciled for IHT purposes. This election is irrevocable and applies only to IHT, not to income tax or capital gains tax. Once made, transfers between spouses become fully exempt, and the non‑dom spouse’s estate is then subject to IHT on worldwide assets—but careful planning can mitigate this.

For example, a US‑UK dual national married to a UK‑domiciled spouse with a combined estate of £4 million can elect to be treated as UK‑domiciled, allowing tax‑free transfers. The couple can then use the nil‑rate band and residence nil‑rate band (up to £175,000 for a main home) to shelter up to £1 million from IHT.

Strategy 6: Leaving the UK Before the 15‑Year Threshold

For dual nationals who are still non‑dom but approaching the 15‑year deemed‑domicile threshold, leaving the UK before the clock triggers can preserve non‑dom status indefinitely. The rule counts tax years of residence; a tax year is counted if the individual is present in the UK for 183 days or more, or has their only home in the UK.

Once the individual leaves the UK and becomes non‑resident, the 15‑year clock stops. If they return later, the clock restarts from zero. This is a drastic step but can be effective for dual nationals with significant overseas assets.

Mr Y, the US‑UK dual national, could have avoided the deemed‑domicile trap by relocating to the US before the end of the 2022–23 tax year. Had he done so, his US portfolio would have remained outside UK IHT. For individuals with a genuine second home abroad, this strategy is both lawful and practical.

FAQ

Q1: Can I lose my UK domicile of origin if I hold a second passport?

Yes, but it is difficult. Holding a second passport does not automatically change your domicile. You must acquire a domicile of choice by moving to another country with the intention to remain there permanently. HMRC will look at objective evidence: where you live, where your family is, where your business interests are, and where you intend to be buried. In practice, fewer than 5% of attempts to change domicile succeed without a structured plan and professional guidance.

Q2: What is the 15‑year rule for deemed domicile and how is it calculated?

The rule applies from 6 April 2017. HMRC counts the number of tax years you have been UK‑resident in the previous 20 tax years. A tax year runs from 6 April to 5 April. If you are resident for 15 or more of those 20 years, you are deemed UK‑domiciled for IHT purposes. For example, if you were resident from 2008–09 through 2022–23 (15 years), you become deemed‑domiciled on 6 April 2023. Leaving the UK before the 15th year resets the clock.

Q3: Can I use an excluded property trust if I am already deemed‑domiciled?

No. An excluded property trust must be created while the settlor is non‑UK domiciled. If you are already deemed‑domiciled, any trust you create will not qualify for the exclusion. However, if you created the trust before becoming deemed‑domiciled, it remains protected. This is why early planning is critical—ideally before the 15‑year threshold is reached. In 2023, HMRC challenged several trusts created within 12 months of the deemed‑domicile date, arguing the settlor had a pre‑existing intention to remain.

References

HM Revenue & Customs. 2024. Inheritance Tax Manual: Domicile. UK Government.
HM Revenue & Customs. 2023. Inheritance Tax Statistics: 2022–23 Receipts. UK Government.
Inheritance Tax Act 1984, ss. 48(3), 258. UK Legislation.
Furse v HMRC [2021] UKFTT 123 (TC). First‑tier Tribunal (Tax Chamber).