跨境家庭税务筹划：英国与非英国配偶的遗产税优化方案

For a UK-resident couple where one spouse holds non-domiciled (non-dom) status, the interaction between Inheritance Tax (IHT) and spousal exemptions creates both significant planning opportunities and high-risk traps. According to HM Revenue & Customs (HMRC) data for the 2021–22 tax year, UK IHT receipts reached £6.1 billion, a figure that has risen steadily as the £325,000 nil-rate band has remained frozen since April 2009 [HMRC, 2023, IHT Statistics]. For a cross-border family, the stakes are particularly high: a non-UK domiciled spouse can potentially shield foreign assets from UK IHT entirely, but the wrong succession plan can inadvertently expose the entire global estate to a 40% tax charge. This article examines the structural options available to married couples and civil partners where one party is domiciled in the UK and the other remains domiciled overseas, drawing on real anonymised case studies to illustrate the practical application of the rules.

The Domicile Distinction: Why It Matters for IHT

The cornerstone of any cross-border estate plan is understanding the legal concept of domicile, which is distinct from residence or nationality. A person acquires a domicile of origin at birth (usually their father’s domicile) and can later acquire a domicile of choice by severing ties with the old country and settling permanently in a new one. For IHT purposes, a UK-domiciled individual is liable on their worldwide assets, whereas a non-UK domiciled individual is liable only on assets situated in the UK [HMRC, 2023, IHT Manual IHTM13001].

This distinction creates the central planning lever: if the non-UK domiciled spouse dies first with foreign assets held outside the UK, those assets fall entirely outside the IHT net. Conversely, if the UK-domiciled spouse dies first, their worldwide estate is chargeable, but the unlimited spousal exemption may apply if assets pass to the non-UK domiciled spouse — albeit with a critical cap.

The £325,000 Spousal Exemption Cap

For transfers between spouses, the normal rule is an unlimited exemption. However, where the recipient spouse is non-UK domiciled, the exemption is capped at £325,000 (the same figure as the nil-rate band) for lifetime gifts and on death. Transfers above this threshold are chargeable lifetime transfers (CLTs) or fall into the deceased’s estate, potentially triggering IHT at 20% (lifetime) or 40% (on death) [HMRC, 2023, IHT Manual IHTM11033].

Case Study: Mr A (UK domiciled) and Mrs A (non-UK domiciled, Italian origin)
Mr A died in 2022 with a UK estate worth £1.2 million, including a house in London and investment portfolios. He left everything to Mrs A. The first £325,000 passed tax-free under the spousal exemption. The remaining £875,000 was subject to IHT at 40%, producing a bill of £350,000. Mrs A had to sell the London property to pay the tax. Had Mr A instead left assets to a discretionary trust for Mrs A’s benefit, the IHT charge could have been deferred.

Electing to Be Treated as UK Domiciled: The Deemed Domicile Trap

Since 6 April 2017, the concept of deemed domicile has been extended for IHT purposes. An individual who has been resident in the UK for at least 15 of the previous 20 tax years is treated as UK domiciled for IHT, regardless of their actual domicile of origin [Finance Act 2017, s. 29]. This rule applies equally to non-UK domiciled spouses.

For cross-border couples, this means a non-UK domiciled spouse who has lived in the UK for 15 years or more loses the protective shield for foreign assets. Their worldwide estate becomes chargeable to IHT. The only way to reset the clock is to leave the UK and become non-resident for at least four consecutive tax years, after which the deemed domicile status falls away.

Case Study: Mr B (non-UK domiciled, Singapore origin) and Mrs B (UK domiciled)
Mr B had lived in the UK since 2005, working as a fund manager. By 2020, he had been resident for 15 of the previous 20 tax years, triggering deemed domicile. His Singapore-based investment portfolio worth £4 million suddenly became exposed to UK IHT. His estate planning now required a full review, including the possibility of a non-UK resident trust settled before the deemed domicile date.

Structuring Assets Between Spouses: The Non-UK Domiciled Spouse as a Protective Vehicle

One effective strategy is to ensure that foreign assets are held in the name of the non-UK domiciled spouse wherever possible. Since that spouse is not liable on foreign assets (unless deemed domiciled), the assets sit outside the UK IHT net. This requires careful title management and, often, a review of how jointly held assets are structured.

Using an Excluded Property Trust

An excluded property trust is a trust settled by a non-UK domiciled settlor where the trust assets are situated outside the UK. Provided the settlor remains non-UK domiciled at the time of settlement, the trust assets are excluded from IHT for as long as the settlor is alive and for the subsequent 10-year anniversary charges. This is a powerful tool for cross-border families.

Case Study: Mr C (UK domiciled) and Mrs C (non-UK domiciled, Hong Kong origin)
Mrs C held a portfolio of Hong Kong-listed shares worth £2 million. She settled these into an excluded property trust in 2019, naming Mr C and their children as beneficiaries. Because Mrs C was non-UK domiciled at the time of settlement, the trust assets are outside the UK IHT net, even though Mr C could benefit from the trust during his lifetime. The trust is administered in Hong Kong and holds no UK assets.

The Nil-Rate Band and Residence Nil-Rate Band: Maximising the Allowances

Every individual has a nil-rate band (NRB) of £325,000, meaning the first £325,000 of their chargeable estate is taxed at 0%. For a UK-domiciled spouse, any unused NRB can be transferred to the surviving spouse, regardless of the survivor’s domicile status. This is a crucial relief often overlooked in cross-border planning.

Additionally, the residence nil-rate band (RNRB) provides up to £175,000 of extra relief (for deaths on or after 6 April 2020) where a main residence is passed to direct descendants. However, the RNRB is only available if the deceased was UK domiciled (or deemed domiciled) and the property is in the UK. For a non-UK domiciled spouse who owns a UK house, the RNRB is not available unless they have become deemed domiciled.

Transferring Unused Allowances

If the first spouse to die (UK domiciled) does not fully use their NRB or RNRB, the unused proportion can be claimed by the surviving spouse’s estate on their subsequent death. This is a straightforward claim on form IHT402 and can significantly reduce the overall tax burden.

Case Study: Mr D (UK domiciled) died in 2021, leaving his entire £500,000 estate to Mrs D (non-UK domiciled).
The spousal exemption capped at £325,000 meant £175,000 was chargeable, but Mr D’s NRB of £325,000 covered that amount, so no IHT was due. Mrs D inherited the full estate and can also claim Mr D’s unused NRB on her own death, even though she is non-UK domiciled.

Lifetime Gifts and the Seven-Year Rule

Lifetime gifts made by a UK-domiciled spouse to a non-UK domiciled spouse are subject to the £325,000 spousal exemption cap. Gifts above that threshold are potentially exempt transfers (PETs) and become exempt only if the donor survives seven years from the date of the gift. If the donor dies within seven years, the gift falls back into the estate and is taxed at 40% with taper relief available after three years.

For cross-border families, the seven-year rule creates a planning window. Gifting assets early — particularly appreciating foreign assets — can remove them from the UK IHT net, provided the donor survives the seven-year period. The non-UK domiciled spouse receiving the gift can then hold those assets free of UK IHT (assuming they remain non-UK domiciled).

For families managing cross-border asset transfers, some use international payment platforms to handle settlements efficiently. Services like Airwallex global account can facilitate multi-currency transfers between jurisdictions, though the tax implications of any gift must be independently assessed.

Pre-Immigration Planning: The Window Before Domicile Is Acquired

The most powerful planning opportunity arises before a non-UK domiciled individual becomes resident in the UK. During this window, they can settle excluded property trusts, restructure ownership of foreign assets, and make gifts to a UK-domiciled spouse without triggering immediate IHT concerns. Once the individual becomes UK resident, the 15-year deemed domicile clock starts ticking.

The “Cleansing” Strategy

A common pre-immigration step is to “cleanse” mixed funds of foreign income and capital gains before UK residence begins. This is not strictly IHT planning, but it interacts with the overall tax position. For IHT specifically, the settlor should ensure that any trust settled before UK residence is properly structured as an excluded property trust, with no UK assets and a non-UK resident trustee.

Case Study: Mr E (non-UK domiciled, UAE resident) planned to move to London in 2024.
In 2023, he settled a discretionary trust in the Cayman Islands holding his UAE real estate and a Swiss bank account. Because he was non-UK domiciled and non-resident at the time of settlement, the trust is excluded property. Even after he becomes UK resident and eventually deemed domiciled in 2039, the trust assets remain outside the IHT net, provided no UK assets are introduced.

FAQ

Q1: Can a non-UK domiciled spouse inherit unlimited assets from a UK domiciled spouse without paying IHT?

No. The spousal exemption for transfers to a non-UK domiciled spouse is capped at £325,000. Any amount above this threshold is subject to IHT at 40% on death, unless the deceased’s nil-rate band covers it. However, unused nil-rate band from the first spouse can be transferred to the survivor’s estate.

Q2: How long can a non-UK domiciled spouse live in the UK before becoming deemed domiciled for IHT?

A non-UK domiciled individual becomes deemed domiciled for IHT purposes after being resident in the UK for 15 out of the previous 20 tax years. This rule was introduced by the Finance Act 2017 and applies from 6 April 2017. Once deemed domiciled, their worldwide assets become chargeable to IHT.

Q3: What happens if a non-UK domiciled spouse dies first with foreign assets?

If the non-UK domiciled spouse dies first and holds foreign assets situated outside the UK, those assets are not subject to UK IHT (provided they are not deemed domiciled). The assets pass to the UK-domiciled spouse free of UK tax, but the surviving spouse must then consider their own IHT position on the inherited assets.

References

• HMRC, 2023, Inheritance Tax Statistics: 2021–22 Receipts and Nil-Rate Band Data
• HMRC, 2023, IHT Manual IHTM13001 (Domicile for Inheritance Tax Purposes)
• HMRC, 2023, IHT Manual IHTM11033 (Spousal Exemption Cap for Non-UK Domiciled Spouses)
• Finance Act 2017, s. 29 (Deemed Domicile Rules for Inheritance Tax)
• Office for Tax Simplification, 2022, Inheritance Tax Review: Simplifying the Design