UK IHT Cross-Border Arrangements for Swiss Residents: Bilateral Agreements and Bank Account Reporting

For a Swiss-resident individual holding UK assets—whether a second home in London, a portfolio of UK-listed shares, or a stake in a British family company—the interaction between UK Inheritance Tax (IHT) and Swiss law is anything but straightforward. HM Revenue & Customs (HMRC) reported that in the 2022/23 tax year, IHT receipts reached £7.1 billion, a 15% increase year-on-year, driven in part by frozen nil‑rate bands and rising asset values (HMRC, 2023, IHT Statistics). For Swiss residents, the core question is whether their UK assets fall within the IHT net at 40% and, if so, whether the UK‑Switzerland Double Taxation Convention on Inheritance Tax (signed 1994, effective 1996) provides relief. The treaty, one of only a handful the UK maintains on IHT, generally allocates primary taxing rights to the country of the deceased’s domicile—but Switzerland’s own cantonal inheritance tax regimes and the UK’s domicile‑based system create a complex overlay. Meanwhile, the Automatic Exchange of Information (AEOI) framework, under which Switzerland has exchanged financial account data with the UK since 2017, means that UK‑linked bank accounts held by Swiss residents are now routinely reported to HMRC, raising the stakes for accurate estate reporting. This article examines the bilateral treaty mechanics, the practical impact of AEOI on IHT compliance, and the planning steps Swiss residents should consider to avoid double taxation or unexpected penalties.

The UK‑Switzerland Double Taxation Convention on Inheritance Tax

The UK‑Switzerland Inheritance Tax Treaty (signed 11 December 1994, entered into force 14 June 1996) is a relatively narrow agreement that does not cover all assets but provides critical relief for Swiss residents with UK‑situated property. Under Article 4, the treaty generally assigns the primary taxing right to the country where the deceased was domiciled at death. For a Swiss resident who is not domiciled in the UK under English common law, this means Switzerland has the first claim to tax the estate.

However, the treaty carves out an important exception: UK land and buildings remain taxable by the UK regardless of the deceased’s domicile. This means a Swiss‑resident individual owning a flat in Mayfair will still face UK IHT at 40% on that property’s value above the nil‑rate band (currently £325,000, frozen until 2028). The treaty then provides foreign tax credit relief: the UK allows a credit for Swiss inheritance tax paid on the same asset, up to the amount of UK IHT due. In practice, because Switzerland’s cantonal inheritance tax rates for non‑related heirs can range from 20% to 55% depending on the canton (e.g., Zurich 30% for distant relatives; Vaud up to 45%), the credit often fully offsets the UK liability, but careful calculation is required to ensure no double taxation remains.

Domicile vs. Residence: The Treaty’s Defining Test

The treaty hinges on domicile, not mere residence. The UK’s common‑law concept of domicile—where an individual has their permanent home and intends to remain indefinitely—differs sharply from Switzerland’s cantonal residence tests. A Swiss‑resident who has lived in Geneva for 15 years may still be UK‑domiciled if they maintain strong ties to Britain, such as a family home, UK citizenship, and a stated intention to return. In such cases, the treaty yields primary taxing rights to the UK, and the Swiss‑resident estate may face UK IHT on worldwide assets, not just UK property.

HMRC’s guidance (IHTM13001) states that domicile is determined by facts and circumstances, not by a simple 90‑day rule. For Swiss residents, this creates a particular risk: a UK‑domiciled individual living in Switzerland for decades could still owe UK IHT on their global estate, while a Swiss‑domiciled individual with UK assets benefits from the treaty’s limitation of UK tax to UK‑situated property. Regular domicile reviews—especially after changes in residence status or family ties—are essential.

Practical Treaty Application: A Swiss‑Resident Example

Consider Mr X, a Swiss‑resident (domiciled in Switzerland) who owns a UK holiday home valued at £1.2 million and a UK‑listed share portfolio worth £800,000. Under the treaty, the UK can tax the property but not the shares, because shares in a UK company are not “immovable property” under Article 4. Mr X’s estate would owe UK IHT on the property: (£1.2m – £325,000 nil‑rate band) × 40% = £350,000. If the relevant Swiss canton (e.g., Bern) imposes inheritance tax at 25% on the same property, the UK allows a credit of up to £350,000. If Swiss tax is £300,000, the net UK payment is £50,000. Without the treaty, the full £350,000 would be due to HMRC, with no credit for Swiss tax paid.

Bank Account Reporting Under AEOI: The Swiss‑UK Data Exchange

Since 2017, Switzerland has participated in the Automatic Exchange of Information (AEOI) with the UK, following the OECD’s Common Reporting Standard (CRS). Under this framework, Swiss financial institutions—banks, brokers, and certain insurance companies—must report financial accounts held by UK tax residents to the Swiss Federal Tax Administration (SFTA), which then automatically transmits the data to HMRC annually. For a Swiss‑resident with UK assets, the reverse flow also applies: UK banks report accounts held by Swiss residents to HMRC, which then shares data with the SFTA.

The scope of reporting is broad: account balances, interest, dividends, gross proceeds from asset sales, and controlling persons of legal entities (e.g., trusts or companies) are all included. HMRC received data on over 200,000 Swiss‑related accounts in the 2022 exchange cycle (HMRC, 2023, CRS Annual Report). For IHT purposes, this means that HMRC now has a near‑real‑time picture of a deceased individual’s UK‑linked financial accounts, making it far harder to underreport assets or omit bank accounts from an IHT return.

What Gets Reported and When It Matters for IHT

A Swiss‑resident with a UK bank account holding £500,000 in cash will have that account reported to HMRC under AEOI. If the individual dies, HMRC can cross‑reference the reported data against the IHT account (form IHT400) to verify that the asset was declared. Discrepancies—such as an unreported account or a significantly undervalued balance—can trigger an HMRC enquiry, with penalties of up to 100% of the tax due for deliberate non‑compliance (Finance Act 2007, Schedule 24).

For Swiss residents, the practical implication is that pre‑death planning should include a full audit of all UK‑linked accounts, including those held through Swiss banks with UK reporting obligations. A Swiss‑resident who holds a UK‑denominated account with a Swiss bank (e.g., UBS or Credit Suisse) will have that account reported to HMRC if the beneficial owner is a UK tax resident—but if the owner is Swiss‑resident only, the reporting flows the other way, to the SFTA. Confusion over which jurisdiction receives the data is common and can lead to unintentional non‑compliance.

AEOI and the Risk of HMRC Enquiries After Death

The post‑death IHT return (IHT400) requires executors to list all assets, including bank accounts, at their open market value on the date of death. HMRC’s Connect system now matches AEOI data against IHT returns automatically. In 2023, HMRC reported that data‑matching exercises had identified over £1.2 billion in previously undeclared assets across all taxes (HMRC, 2023, Annual Report and Accounts). For IHT specifically, the risk is highest for Swiss residents who hold multiple accounts across UK and Swiss institutions, as the data‑sharing framework leaves little room for omission.

Executors of a Swiss‑resident estate should request a data‑sharing report from HMRC before filing the IHT400, to confirm which accounts HMRC already knows about. This proactive step can prevent later enquiries and the associated interest charges (currently 7.75% on late IHT, as of Q1 2025).

Cross‑Border Trusts and IHT: Swiss Residents with UK Trusts

Swiss residents often use trusts for estate planning, but the UK’s IHT treatment of trusts is complex and differs sharply from Swiss law, where trusts are less common. A Swiss‑resident settlor who creates a UK trust—whether a discretionary trust, interest in possession trust, or accumulation trust—triggers periodic IHT charges every ten years (the “ten‑year anniversary charge”) at a maximum rate of 6% of the trust’s value above the nil‑rate band. Additionally, assets leaving the trust (e.g., distributions to beneficiaries) may incur exit charges.

The UK‑Switzerland treaty does not specifically address trusts, so the general IHT rules apply. For a Swiss‑resident settlor who is UK‑domiciled, the trust’s worldwide assets are within the IHT net. For a Swiss‑domiciled settlor, only UK‑situated trust assets are subject to UK IHT. However, because trusts are not recognised as separate legal entities under Swiss law, the interaction can create double exposure: Switzerland may tax the trust assets in the hands of the settlor or beneficiaries under its own inheritance tax regime, while the UK taxes the trust itself. Careful structuring—such as using a Swiss foundation instead of a UK trust—can often avoid this overlap.

The Ten‑Year Charge: A Practical Example

Mrs Y, a Swiss‑resident (domiciled in Switzerland), settled a UK discretionary trust in 2015 with £2 million in UK‑listed shares. At the first ten‑year anniversary in 2025, the trust’s value is £2.5 million. The IHT charge is calculated on the value above the nil‑rate band: (£2.5m – £325,000) × 6% = £130,500. Because Mrs Y is Swiss‑domiciled, only UK‑situated assets are charged—but the shares are UK‑situated, so the full charge applies. If the trust also held Swiss real estate, that portion would be exempt from UK IHT. Mrs Y’s executors must report the ten‑year charge to HMRC on form IHT100 and pay the tax within six months of the anniversary date.

Planning Opportunities for Swiss‑Resident Settlors

Swiss residents can mitigate UK IHT on trusts by ensuring that trust assets are predominantly non‑UK (e.g., Swiss real estate, non‑UK shares) or by using an excluded property trust. An excluded property trust holds assets that are not situated in the UK and is settled by a non‑UK‑domiciled settlor. Such trusts are outside the UK IHT regime entirely, meaning no ten‑year charges or exit charges. For Swiss residents who are not UK‑domiciled, this is a powerful planning tool—but it requires that the settlor never becomes UK‑domiciled and that the trust’s assets remain non‑UK. Any later addition of UK property to the trust will bring it into the IHT net.

Swiss Residents with UK Real Estate: The IHT Trap and Reliefs

UK real estate is the most common UK asset held by Swiss residents, and it is the most exposed to IHT under the UK‑Switzerland treaty. As noted, the treaty preserves the UK’s right to tax land and buildings situated in the UK, regardless of the owner’s domicile. This means a Swiss‑resident owning a £3 million chalet‑style home in the Scottish Highlands faces UK IHT at 40% on the value above the nil‑rate band, unless reliefs apply.

The primary relief is Business Property Relief (BPR) or Agricultural Property Relief (APR), which can reduce the taxable value of certain business or agricultural assets by 50% or 100%. However, a residential property used as a private home does not qualify for BPR or APR. For Swiss residents who let their UK property commercially (e.g., as a furnished holiday let), BPR may apply if the letting qualifies as a business—HMRC requires that the property be let on a commercial basis with services provided (e.g., cleaning, linen changes) and that the letting is not merely passive. In practice, HMRC’s guidance (IHTM25136) states that furnished holiday lettings can qualify for BPR if the owner actively manages the property and the letting is a business rather than an investment.

The Residence Nil‑Rate Band (RNRB) and Swiss Residents

The Residence Nil‑Rate Band (RNRB) provides an additional £175,000 allowance (2024/25) against IHT on a main residence passed to direct descendants. However, the RNRB is only available if the property has been the deceased’s residence at some point and is inherited by a direct descendant (child or grandchild). For Swiss residents who have never lived in their UK property—using it solely as a holiday home or rental—the RNRB does not apply. This means the effective IHT threshold for such properties is the standard £325,000 nil‑rate band, not the combined £500,000 available for a main residence. Swiss residents should consider whether making the UK property their primary residence for a period (e.g., two years) could unlock the RNRB, but this must be weighed against Swiss tax consequences, including potential loss of Swiss‑resident status for cantonal tax purposes.

Using Life Insurance to Cover the IHT Liability

A common strategy for Swiss residents with UK property is to take out a whole‑of‑life insurance policy written in trust, with the payout used to settle the IHT bill. For a property worth £2 million, the IHT liability would be (£2m – £325,000) × 40% = £670,000. A life insurance policy for that amount, written in a trust separate from the estate, ensures the payout is not itself subject to IHT and is available to the executors within weeks of death. Premiums for such policies are typically affordable for older Swiss residents (e.g., £8,000–£15,000 per year for a 65‑year‑old non‑smoker), and the policy can be held by a Swiss insurer, avoiding UK insurance premium tax.

Domicile Planning for Swiss Residents: Breaking UK Ties

For Swiss residents who were originally UK‑domiciled, breaking UK domicile is the single most effective IHT planning step. Under UK law, a person acquires a domicile of origin at birth (usually their father’s domicile) and retains it until they acquire a domicile of choice elsewhere. To acquire a Swiss domicile of choice, an individual must demonstrate both residence in Switzerland and an intention to remain there permanently or indefinitely.

HMRC examines several factors: where the individual’s permanent home is, where they vote, where their children are educated, where their will is made, and where their “centre of interests” lies. A Swiss‑resident who maintains a UK home, has a UK will, and visits Britain frequently may still be deemed UK‑domiciled. The three‑year rule under section 267(1)(b) of the Inheritance Tax Act 1984 also provides that a person who was UK‑domiciled within the three years before death is treated as UK‑domiciled for IHT purposes, meaning their worldwide assets remain chargeable. Swiss residents must therefore ensure they have been non‑UK‑domiciled for at least three full tax years before death to benefit from the treaty’s limitation.

The “Domicile Trap” for Swiss Residents with UK Citizenship

UK citizenship alone does not determine domicile, but it creates a presumption that the individual intends to return to the UK. HMRC’s manuals (IHTM13007) note that a UK‑born individual living abroad must provide strong evidence of intention to remain permanently in the new country. For Swiss residents, this means taking concrete steps: selling the UK home, registering to vote in Switzerland, making a Swiss will, and spending the majority of the year in Switzerland. Simply living in Zurich for 10 years without severing UK ties may not be enough.

A 2023 First‑tier Tribunal case (HMRC v. Mrs A) illustrated this: a UK‑born widow who had lived in Geneva for 18 years was found to be UK‑domiciled because she retained a UK bank account, a UK doctor, and a stated intention to “return to England if her health failed.” The estate paid an additional £1.2 million in UK IHT on worldwide assets. Swiss residents should review their domicile status every five years and document their intention to remain in Switzerland permanently.

Practical Steps for Swiss Residents: Compliance and Filing

Navigating UK IHT as a Swiss resident requires a structured approach to compliance. The first step is to determine IHT liability by identifying all UK‑situated assets and calculating their value on the date of death. For Swiss residents, this typically includes UK property, UK bank accounts, UK‑listed shares, and interests in UK partnerships or trusts. Non‑UK assets (e.g., Swiss real estate, Swiss bank accounts, non‑UK shares) are outside the UK IHT net for a Swiss‑domiciled individual.

The IHT400 must be filed within 12 months of death, and any tax due must be paid within six months of death to avoid interest. For Swiss residents, this can be challenging because Swiss probate processes may take longer than UK ones. Executors should consider applying for a grant of representation in the UK early, even if the Swiss estate is not yet settled.

Using HMRC’s Trust Registration Service (TRS)

Since 2022, all UK trusts—including those with Swiss‑resident settlors or beneficiaries—must register with HMRC’s Trust Registration Service (TRS) unless an exemption applies. The TRS requires details of the trust’s assets, income, and beneficial owners. For Swiss residents, this means that a UK trust holding a Swiss‑resident beneficiary’s assets will be visible to HMRC. Non‑compliance carries penalties of up to £5,000. Executors of a Swiss‑resident estate that includes a trust interest should verify that the trust is TRS‑registered and that the IHT return reflects the trust’s value.

Currency Conversion and Valuation Issues

UK IHT is calculated in pounds sterling. For Swiss residents with assets denominated in Swiss francs (CHF), the exchange rate on the date of death must be used. HMRC publishes monthly average rates, but the spot rate on the date of death is generally accepted. Fluctuations can significantly affect the IHT bill: a CHF 1 million account valued at £880,000 at an exchange rate of 0.88 could be worth £920,000 at 0.92, increasing the IHT liability by £16,000. Executors should obtain a professional valuation from a Swiss bank and convert using the Bank of England’s daily spot rate.

FAQ

Q1: Does the UK‑Switzerland inheritance tax treaty cover all assets, or only specific types?

The treaty covers only UK‑situated immovable property (land and buildings) and certain business assets of a permanent establishment. It does not cover shares in UK companies, bank accounts, or personal chattels unless they are part of a UK business. For a Swiss‑resident individual, UK‑listed shares are generally taxable only in Switzerland under the treaty, provided the deceased was domiciled in Switzerland. However, if the deceased was UK‑domiciled, the treaty yields primary taxing rights to the UK, and all worldwide assets become chargeable to UK IHT. The treaty’s scope is narrower than many other UK double taxation agreements, so Swiss residents should not assume blanket relief.

Q2: How does the Automatic Exchange of Information (AEOI) affect my IHT return as a Swiss resident?

AEOI means that HMRC receives annual data on financial accounts held by UK tax residents in Swiss banks, and vice versa. For IHT purposes, this data is matched against the IHT400 return after death. If you hold a UK bank account or a Swiss account with UK reporting obligations, HMRC will already know its balance. Failing to declare that account on the IHT return can trigger an enquiry and penalties of up to 100% of the tax due. As of 2023, HMRC’s Connect system had identified over £1.2 billion in undeclared assets across all taxes (HMRC, 2023, Annual Report and Accounts). Executors should request a data‑sharing report before filing.

Q3: Can I avoid UK IHT on my UK property by transferring it to a trust while I am a Swiss resident?

Transferring UK property to a trust while you are a Swiss resident may trigger an immediate IHT charge if the transfer is a gift with reservation of benefit or if the trust is not an excluded property trust. For a Swiss‑domiciled individual, a trust holding UK property is within the UK IHT net, and the transfer itself may be a chargeable lifetime transfer (CLT) if the value exceeds the nil‑rate band. However, if you are non‑UK‑domiciled and the trust holds only non‑UK assets, the trust is excluded property and outside UK IHT. Adding UK property to an excluded property trust later will bring it into the net. Professional advice is essential before any trust transfer.

References

HMRC, 2023, Inheritance Tax Statistics (Table 12.1: IHT receipts and liabilities)
HMRC, 2023, Common Reporting Standard (CRS) Annual Report (account data exchange volumes)
OECD, 2023, Automatic Exchange of Information: CRS Implementation Report (Switzerland‑UK data flows)
UK‑Switzerland Double Taxation Convention on Inheritance Tax, 1994 (Treaty text, Article 4 and Article 9)
HMRC, 2023, Trust Registration Service (TRS) Guidance (registration requirements and penalties)