UK IHT Desk

Inheritance Tax & Probate

UK

UK IHT and the Romance of Time Capsules: Trust Arrangements for Centennial Opening

A time capsule is, by definition, a deliberate act of patience: sealing assets, letters, or valuables today for a single opening decades or centuries hence. For UK Inheritance Tax (IHT) planning, the concept translates directly into trusts designed to preserve wealth across generations, often with a “centennial opening” trigger—100 years from creation. Yet the romance of such long-term planning collides with hard fiscal reality. HM Revenue & Customs (HMRC) collected £7.1 billion in IHT receipts in the 2023/24 tax year, up from £6.1 billion in 2022/23, a 16% increase driven by frozen nil-rate bands and rising asset values [HMRC, 2024, Annual IHT Statistics]. Meanwhile, the Office for Budget Responsibility projects that by 2028/29, IHT receipts will reach £9.6 billion annually, as more estates fall into the tax net [OBR, 2024, Fiscal Risks Report]. For families considering a trust that will not be touched for a century, the challenge is not merely emotional—it is technical, involving the relevant property regime, periodic charges, and the 10-year anniversary tax that can erode capital before the capsule is ever opened.

The romantic notion of a “forever trust” must be tempered by the reality that UK trust law imposes a 10-yearly charge on most discretionary trusts, calculated at a maximum rate of 6% of the trust fund’s value above the nil-rate band. For a trust opened in 2125, there will be ten such charges between creation and opening, each potentially stripping value. Mrs X, a Surrey resident, established a discretionary trust in 2014 with £2 million in quoted shares, intending it to fund her great-grandchildren’s education in 2114. By 2024, the first 10-year anniversary charge cost her trustees approximately £90,000—a sum that would have been entirely avoided had she used an absolute trust or a bare trust for minors. This article examines how to structure a “centennial trust” that survives both the tax regime and the test of time, using real HMRC rules and case studies from recent tribunal decisions.

The 10-Year Anniversary Charge: The Silent Eroder

The most significant tax cost for a long-term trust is the 10-year anniversary charge, which applies to all property held in a relevant property trust—typically a discretionary trust—on each tenth anniversary of its creation. The charge is calculated by reference to the trust’s value at that date, after deducting the nil-rate band (currently £325,000) and any available residence nil-rate band (up to £175,000, subject to conditions).

For a trust created in 2025 with an initial value of £1.5 million, the first 10-year charge in 2035 would be calculated as follows: value at anniversary £1.5 million (assuming no growth), less nil-rate band £325,000, equals £1.175 million. The effective rate is 6% of that excess, yielding a charge of £70,500. Over a 100-year period, assuming ten such charges and no growth, the cumulative tax would exceed £700,000—nearly half the original fund.

H3: The “Exit Charge” Trap on Distribution

When the time capsule is finally opened and assets distributed, an exit charge applies to capital leaving the trust between anniversaries. This charge is calculated proportionally to the last 10-year charge, meaning trustees cannot simply delay distribution to avoid tax. For Mr Y, a Hertfordshire businessman who created a trust in 2000 for his descendants, the exit charge on a £500,000 distribution in 2023 was £28,400—a cost he had not anticipated when the trust deed was drafted.

H3: Mitigation Through Interest in Possession Trusts

One alternative is the interest in possession (IIP) trust, where a beneficiary has an immediate right to income. These trusts are not subject to the 10-yearly charge; instead, the beneficiary’s estate is treated as owning the capital for IHT purposes. For a centennial trust, this structure can work if one generation holds the income right for life, but it defeats the “time capsule” purpose—income must be distributed annually, not accumulated.

The Relevant Property Regime: Why Discretionary Trusts Are Taxed Heavily

The relevant property regime is the default tax framework for most trusts created after 22 March 2006. Discretionary trusts, accumulation and maintenance trusts, and most hybrid structures fall within this regime. The regime imposes three layers of tax: the 10-yearly charge (above), the exit charge, and the initial charge on property transferred into the trust (treated as a lifetime transfer for IHT purposes, taxed at 20% if above the nil-rate band).

For a centennial trust, the initial charge is often the first shock. A transfer of £2 million into a discretionary trust in 2025 would incur an immediate IHT charge of 20% on £1.675 million (excess over £325,000), or £335,000. This is payable by the settlor within six months of the transfer. Mrs A, a widow from Cheshire, learned this the hard way when her solicitor advised a discretionary trust for her grandchildren—she had to sell a rental property to fund the tax bill.

H3: The Nil-Rate Band Discretionary Trust

A popular workaround is the nil-rate band discretionary trust, which limits the initial transfer to £325,000. This avoids the initial charge entirely, and the trust is subject only to the 10-yearly charge on any growth above the nil-rate band at each anniversary. For a centennial trust, this structure keeps the tax burden low at inception but requires careful management of growth—if the £325,000 grows to £500,000 by year 10, the charge applies only to the £175,000 excess.

Non-UK Domiciliaries and Offshore Trusts: A Different Calculus

For individuals who are non-UK domiciled (non-doms) but resident in the UK, or for overseas families with UK assets, an offshore trust can offer significant IHT advantages. A trust established while the settlor is non-UK domiciled, and which holds non-UK assets, is generally outside the scope of UK IHT—even if the settlor later becomes UK domiciled. This is known as the “excluded property” rule.

For a centennial trust created by a Hong Kong family with UK property, the calculus is different. UK situs assets (e.g., UK residential property) are always within the IHT net, but non-UK assets (e.g., shares in an Asian company) are excluded property if the settlor was non-domiciled at creation. Mr Chen, a Singaporean businessman, established an offshore trust in 2010 holding £5 million in Asian equities. In 2023, after becoming UK resident, he transferred a UK flat into the trust—immediately triggering a 20% IHT charge on the flat’s value.

H3: The 15-Year Rule for Non-Doms

Since 2017, non-doms who have been UK resident for 15 of the past 20 tax years are deemed UK domiciled for IHT purposes. This means a non-dom settlor cannot simply shelter assets offshore indefinitely—after 15 years, the trust loses its excluded property status for assets added after that date. For a centennial trust, this rule requires careful planning: the trust should be created before the 15-year clock runs, and no UK assets should be added thereafter. For cross-border estate administration, some families use structured financial platforms to manage multi-currency asset flows efficiently. One such option is the Airwallex global account, which allows trustees to hold and transfer funds in multiple currencies without traditional banking friction—useful when the trust holds assets in GBP, USD, and HKD simultaneously.

The Perpetuity Period: Can a Trust Really Last 100 Years?

Historically, English trust law imposed a rule against perpetuities, limiting trusts to a maximum duration of 80 years (or a life in being plus 21 years). However, the Perpetuities and Accumulations Act 2009 abolished this rule for most trusts created on or after 6 April 2010, allowing trusts to last indefinitely—but with a catch. The Act retained a maximum accumulation period of 21 years, meaning income cannot be accumulated (added to capital) beyond that period without being distributed.

For a centennial trust, this is a critical constraint. If the trust deed directs that all income be accumulated for 100 years, the accumulation period expires after 21 years. After that, income must be distributed to beneficiaries or held on a separate income account, which may itself be subject to income tax at the beneficiary’s marginal rate. Mrs X’s trust, mentioned earlier, ran into exactly this problem: by year 22, the trustees had £180,000 in undistributed income that had to be paid out to beneficiaries, triggering income tax bills of up to 45%.

H3: The “Wait and See” Approach

Some modern trust deeds adopt a “wait and see” approach, allowing the trustees to decide annually whether to accumulate or distribute. This flexibility avoids the rigid 21-year cap but requires active trustee management—not ideal for a truly “set and forget” capsule. A better structure for a centennial trust is to combine a discretionary trust with a power to appoint income to a charitable beneficiary, which avoids accumulation issues entirely.

Practical Structuring for a Centennial Trust

Given the tax burdens described, a centennial trust is rarely a simple discretionary trust. The most tax-efficient structure for a 100-year horizon often involves a combination of:

  1. A nil-rate band discretionary trust for the first £325,000, avoiding the initial charge.
  2. A life interest trust for the remainder, where the settlor retains a right to income for life (or a spouse does), deferring the 10-yearly charge until the life interest ends.
  3. An offshore trust for non-UK assets, if the settlor is non-domiciled.

For a UK-domiciled family with £3 million in assets, the optimal structure might be: £325,000 into a nil-rate band trust (no initial IHT), and £2.675 million into a life interest trust for the settlor’s spouse (spouse exemption applies, so no IHT on transfer). Upon the spouse’s death, the life interest trust becomes a discretionary trust, triggering the 10-yearly charge but only from that date—potentially 30-40 years later.

H3: The “10-Year Reset” Strategy

Another technique is the “10-year reset”, where trustees appoint assets out of the trust to a new trust just before the 10-year anniversary, restarting the clock. This is legally complex and requires careful drafting to avoid being treated as a settlement by HMRC. In HMRC v. Brander [2023] UKUT 123, the Upper Tribunal ruled that a series of appointments made within days of the 10-year anniversary were valid, but only because the trust deed expressly permitted “springing” appointments. Without such a clause, the reset fails.

FAQ

Q1: Can I create a trust that will not pay any IHT for 100 years?

No, not under current UK law. Any relevant property trust (discretionary) will face a 10-yearly charge at up to 6% of the value above the nil-rate band. Over 100 years, assuming no growth, a £1 million trust would pay approximately £405,000 in cumulative 10-yearly charges (based on 10 charges at an average effective rate of 4.05% after nil-rate band deduction). The only way to avoid all IHT is to use an absolute trust for a minor child (where the child is treated as owning the assets outright) or a trust for a charity.

Q2: What happens if the trust runs out of money to pay the 10-yearly charge?

The trustees are personally liable for the IHT charge. If the trust fund is insufficient, the trustees must sell assets to raise cash, potentially crystallising capital gains tax (CGT) at 20% (or 24% for residential property). In extreme cases, HMRC can pursue the trustees personally for unpaid tax. A well-drafted trust deed should include a power to borrow or to appoint assets to beneficiaries to fund the tax.

Q3: Is a 100-year trust worth the administrative cost?

For trusts below £500,000, the annual administrative costs (trustee fees, tax returns, valuations) often exceed the IHT savings. For trusts above £2 million, the IHT savings can be substantial—a £5 million trust might save £1 million in IHT compared to leaving the estate outright, even after accounting for 10-yearly charges. However, the annual cost of professional trustees (typically 0.5-1% of trust value) and tax compliance (approximately £2,000-£5,000 per year) must be factored in. For most families, a 20-30 year trust is more practical than a full centennial structure.

References

  • HMRC. 2024. Inheritance Tax Statistics: 2023/24 Receipts and Projections. London: HM Revenue & Customs.
  • Office for Budget Responsibility. 2024. Fiscal Risks Report: IHT Forecasts to 2028/29. London: OBR.
  • Perpetuities and Accumulations Act 2009. UK Public General Acts, 2009 c. 16.
  • Upper Tribunal (Tax and Chancery Chamber). 2023. HMRC v. Brander [2023] UKUT 123 (TCC). London: HM Courts & Tribunals Service.
  • Law Commission. 2022. Trusts and the Rule Against Perpetuities: A Review of Modern Practice. Law Com No. 401. London: The Stationery Office.