Rule Against Perpetuities UK: Perpetuities and Accumulations Act 2009 Explained

Updated 31 May 2026 · 9 min read · Trusts & Will Law

The rule against perpetuities prevents a testator from tying up property in a trust forever. The Perpetuities and Accumulations Act 2009 replaced the notoriously complex common law rule with a single, fixed 125-year perpetuity period and a simple wait-and-see approach — making the rule almost invisible in routine modern will drafting, but still important for unusual contingent gifts.

Why the Rule Exists

Property law has long resisted “dead hand” control — a testator dictating the ownership and use of property for generations after their death. The rule against perpetuities implements this policy by requiring that future interests in property must vest (or definitely fail) within a defined period. An interest that might vest too far in the future is void, ensuring that property eventually circulates freely.

At common law, the rule was applied with a theoretical rigour that produced absurd results: a gift void from the outset because of a theoretical scenario involving an 80-year-old woman being medically presumed capable of having children (the “fertile octogenarian”). The courts did not examine what was likely to happen — only what was possible. Statute had to intervene twice: first with the Perpetuities and Accumulations Act 1964, and definitively with the Perpetuities and Accumulations Act 2009.

The Perpetuities and Accumulations Act 2009: Key Changes

The PAA 2009 applies to instruments taking effect on or after 6 April 2010. A will speaks from the date of the testator’s death, so the relevant date is the death date — not when the will was signed.

• Fixed 125-year perpetuity period. All future interests must vest within 125 years of the instrument taking effect. There is no option to specify a shorter or longer period.
• Wait-and-see rule (first step, not last resort). Instead of voiding a potentially remote interest immediately, the court waits to see what happens. The interest only fails if it has not vested by the end of the 125-year period.
• Royal lives savings clauses abolished. Under the old law, drafters could nominate “lives in being” (often members of the Royal Family) to extend the perpetuity period. This device no longer works under the PAA 2009 — the 125-year period is absolute.
• Rule against accumulations abolished. For post-April 2010 instruments, there is no separate limit on how long trustees may accumulate income — they may do so throughout the 125-year perpetuity period if the trust deed permits.

How the 125-Year Period Works in a Will Trust

For a will trust (e.g., a discretionary trust for children and grandchildren), the 125-year period runs from the testator’s date of death. The trustees can lawfully hold and administer the trust assets for up to 125 years without any gift failing for perpetuity reasons, provided that at least some beneficiaries have or will acquire vested interests within that period.

The wait-and-see rule means that if, say, a gift is “to my grandchildren who attain 25”, and at the testator’s death it is uncertain whether any grandchild will be born who can attain 25 within 125 years, the gift is not void from the start. The trustees wait. If a grandchild is born and reaches 25 before the 125 years expire, the gift vests and is valid.

For everyday family will trusts — a life interest for a surviving spouse, then to children equally on reaching 18 — the 125-year period is so generous that the rule is essentially irrelevant. Even in more ambitious multi-generation trusts, the 125-year window accommodates most realistic family scenarios.

Old Wills: The Position Before 6 April 2010

For testators who died before 6 April 2010, the common law rule (as reformed by the Perpetuities and Accumulations Act 1964) continues to apply. Key features of the pre-2009 regime:

• Perpetuity period: lives in being at the creation of the interest, plus 21 years
• Alternative fixed period: up to 80 years if specified in the instrument (under the 1964 Act)
• Wait-and-see rule: introduced by the 1964 Act, but only applied after the initial common law analysis
• Fertile octogenarian and unborn widow constructs: still relevant in theory
• Accumulation rules: still apply (various periods under the Law of Property Act 1925, as amended)

Practitioners advising trustees of pre-2010 trusts must still apply the old rules to determine validity of future interests, and the old accumulation periods when advising on income reinvestment.

Abolition of the Rule Against Accumulations

The rule against accumulations (originally codified in the Thellusson Act 1800 and re-enacted in the Law of Property Act 1925) historically restricted the period during which trustees could accumulate income — broadly, the lifetime of the settlor or testator, 21 years from the date of the instrument, the minority of any beneficiary, or the minority of any living person who would be entitled if of full age. These restrictions led to practical difficulties in discretionary trusts where trustees wanted to build up capital rather than distribute income each year.

The PAA 2009 abolishes these restrictions for instruments taking effect after 6 April 2010. Trustees of post-2010 discretionary trusts may accumulate income for the full 125-year period if the trust deed grants that power. This gives much greater flexibility in trust administration, particularly for family investment trusts and trusts for minors where the preference is to compound returns rather than distribute income that beneficiaries cannot practically use.

When Might a Modern Will Trigger the Perpetuity Rule?

In practice, the perpetuity rule bites on modern wills only when a contingent gift is framed in a way that might not resolve within 125 years. Examples of potentially problematic drafting:

• A gift to “the first of my descendants to become a QC or KC” — if no descendant enters the Bar for well over a century, the gift may never vest
• A gift contingent on a specific external event of uncertain timing — e.g., “when the family farm is sold” where sale is restricted by the trust deed
• A chain settlement where the trust has already been running for decades — the 125-year period counts from the original instrument, not each sub-settlement
• Class gifts contingent on attaining an advanced age — e.g., “to my issue who attain 50” — though the wait-and-see rule means these are rarely fatal in practice

Solicitors drafting wills should avoid contingencies that depend on events that may not occur within a normal human lifespan and should use standard trust termination provisions (e.g., a longstop distribution date) to ensure the trust winds up within the perpetuity period if still running.

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