Commorientes UK (2026): What Happens When Two People Die at the Same Time — the Older Dies First Rule

The word 'commorientes' (from the Latin 'dying together') describes the situation where two or more people die in circumstances where the order of their deaths cannot be established on the balance of probabilities. Car accidents, plane crashes, house fires, shipwrecks, and natural disasters commonly give rise to commorientes questions: (1) THE STATUTORY RULE (LAW OF PROPERTY ACT 1925 s.184): where two or more persons have died in circumstances rendering it uncertain which survived the other(s), for all purposes affecting the title to property the deaths are assumed to have occurred in order of seniority — the older is presumed to have died FIRST and the younger is presumed to have survived. Where there are multiple deaths, the oldest is presumed to have died first, the next oldest second, and so on; (2) WHY THE ORDER OF DEATH MATTERS: the survivorship question is critical for succession because it determines who inherits from whom. If H (aged 68) and W (aged 65) die in the same accident: under LPA s.184, H (older) dies first, W (younger) briefly survives. W therefore inherits from H's estate under H's will or intestacy. W's estate is then enlarged by that inheritance. W's estate is then distributed under W's own will or intestacy; (3) THE 'BALANCE OF PROBABILITIES' TEST: before the statutory presumption applies, there must be genuine uncertainty. If medical evidence, accident reports, or witness testimony can establish on the balance of probabilities that one person survived the other — even by minutes — the statutory presumption does not apply. Coroner's inquests and forensic evidence are often critical in these cases; (4) THE PRESUMPTION IS REBUTTABLE BY EVIDENCE: LPA s.184 is a presumption of fact, not a conclusive legal rule. If the court is satisfied that the deaths occurred in a different order, it will apply the evidence — not the presumption; (5) COMMON LAW POSITION WITHOUT A STATUTE: at common law (before 1925), it was necessary to prove survivorship on the balance of probabilities. If proof was impossible, the gift simply failed. The LPA s.184 presumption was introduced to provide certainty.

The commorientes presumption under LPA s.184 applies differently on intestacy than it does for gifts under a will — because of a special exception in the Administration of Estates Act 1925: (1) THE INTESTACY EXCEPTION (AEA 1925 s.46(3)): under the intestacy rules, a surviving spouse or civil partner only inherits if they actually survived the intestate. If it cannot be shown that the spouse survived, they are treated as having PREDECEASED — they do not inherit. This means the spouse exemption and the statutory legacy are NOT paid to the spouse's estate; (2) WHY THE EXCEPTION EXISTS: without AEA s.46(3), applying LPA s.184 to intestacy could produce the following perverse outcome: H (68) and W (65) die in a crash. LPA s.184 presumes H dies first; W is deemed to have survived H briefly. W therefore inherits H's estate on intestacy (statutory legacy + half residue). W's estate (now inflated) is then distributed under W's intestacy rules. This means H's estate passes twice — through W's estate — to W's relatives rather than H's. The AEA s.46(3) exception prevents this by treating neither spouse as having survived the other for intestacy purposes; (3) PRACTICAL EFFECT ON INTESTACY: where a married couple die in a common disaster and neither left a will: (a) H's estate is distributed AS IF W had predeceased H — under H's intestacy rules without a surviving spouse; (b) W's estate is distributed AS IF H had predeceased W — under W's intestacy rules without a surviving spouse; (c) each estate goes to the deceased's own relatives independently; (4) CONTRAST WITH WILLS: for gifts under a will, LPA s.184 applies in full — the older dies first presumption operates unless the will contains a survivorship clause displacing it. Two spouses each leaving everything to the other by will (without a survivorship clause) will result in the younger spouse briefly inheriting from the older, then the younger's estate being distributed under the younger's will or intestacy; (5) IHT AND DOUBLE CHARGE: if the older spouse's estate passes to the younger under LPA s.184, then the younger dies within a short time, the same assets may be subject to IHT twice. Quick succession relief (IHTA s.141) reduces but does not eliminate this double charge.

Survivorship clauses are the standard professional solution to the commorientes problem, providing certainty and avoiding double IHT: (1) WHAT A SURVIVORSHIP CLAUSE DOES: a survivorship clause makes a gift conditional on the beneficiary surviving the testator by a specified period. The most common period is 30 days. Example: 'I give my estate to my husband John, provided he survives me by 30 days. If he does not survive me by 30 days, I give my estate to my children equally'; (2) HOW THIS ADDRESSES THE COMMORIENTES PROBLEM: (a) if the couple die simultaneously or within 30 days of each other, neither benefits from the other's estate. Each estate is distributed to the secondary beneficiaries (children, other relatives) independently; (b) the LPA s.184 older-dies-first presumption becomes irrelevant — even if H is presumed to have died first, W does not satisfy the 30-day survivorship condition, so H's estate still passes to the secondary beneficiaries; (3) IHT PLANNING BENEFIT: when a spouse estate passes to the secondary beneficiaries directly (children), no IHT arises at the first death (children are not exempt — IHT is payable — but the NRB and RNRB can be used). The key benefit is avoiding double IHT — if assets would otherwise pass from H to W (one charge) and then from W to children (second charge), a survivorship clause ensures they only pass once (H to children). Quick succession relief (IHTA s.141) partially mitigates double IHT even without a survivorship clause, but a survivorship clause eliminates the issue; (4) THE RISK — SURVIVORSHIP CLAUSE WITHOUT A SUBSTITUTE: 'I give my estate to my husband, if he survives me by 30 days' (with no alternative provision) — if the husband does not survive 30 days, the gift lapses. Unless the will provides a substitute, the estate falls into residue or intestacy. ALWAYS combine a survivorship clause with named substitute beneficiaries; (5) STANDARD MUTUAL WILLS DRAFTING FOR COUPLES: (a) 'I give my estate to my spouse, if they survive me by 30 days'; (b) 'If my spouse does not survive me by 30 days, I give my estate to my children in equal shares'; (c) 'If any child predeceases me or fails to survive me by 30 days, their share passes to their own children equally.' This three-layer provision covers the commorientes problem, lapse, and the chain of substitution; (6) THE TRNRB CONSIDERATION: a 30-day survivorship clause means that if the spouse dies within 30 days, their share of the RNRB/NRB is NOT used on the first death (the assets do not pass through the spouse). The TNRB and TRNRB are therefore still available in full on the survivor's death — even though that survivor is effectively the secondary beneficiary. This is generally advantageous for IHT.

The interaction of commorientes, survivorship, and IHT is one of the more complex areas of English succession planning: (1) THE DOUBLE IHT PROBLEM WITHOUT A SURVIVORSHIP CLAUSE: H (NRB only — estate £400,000) and W (NRB only — estate £300,000) die in a crash. LPA s.184 applies: H (older) dies first. W inherits H's estate (using the spouse exemption — no IHT on first death). W then dies with a £700,000 estate. IHT: NRB = £325,000; taxable = £375,000; IHT = £150,000. If instead each had left their estate to the children directly (each using their own NRB): H's IHT = £75,000 (£400k - £325k × 40%); W's IHT = £0 (£300k < £325k NRB). Total IHT = £75,000. The double-charge scenario costs £150,000 vs £75,000 — the same assets borne more IHT by passing through the intermediate estate; (2) QUICK SUCCESSION RELIEF (IHTA 1984 s.141): if the same property is charged to IHT twice within 5 years (once on H's death, once on W's death), the second charge is reduced. The relief is: 100% within 1 year; 80% within 1-2 years; 60% within 2-3 years; 40% within 3-4 years; 20% within 4-5 years. In a simultaneous death, H's death and W's death both occur at the same time — the 100% relief applies to any IHT in W's estate on assets received from H; (3) THE SURVIVORSHIP CLAUSE ELECTION: with a 30-day survivorship clause, the mutual wills work as follows: H and W die simultaneously. W does not survive H by 30 days. H's estate passes to the children directly — NRBs used independently. W's estate (unchanged) also passes to the children under W's will. Total IHT = H's estate over NRB + W's estate over NRB — each calculated independently. No double charge; (4) THE RNRB INTERACTION: where both spouses die simultaneously (or within 30 days) with survivorship clauses: (a) if H's estate includes the family home and passes to children (direct descendants), H's RNRB is used; (b) W's RNRB is available on W's estate if W's estate also passes to direct descendants; (c) if H and W had previously transferred the RNRB between them via TRNRB planning (each owned property that passed to descendants), both RNRBs are used independently; (5) HMRC APPROACH: HMRC accepts the s.184 presumption for IHT purposes in the absence of contrary evidence. Executors of both estates should be prepared to provide all available evidence about the sequence of events (medical records, accident reports, witness statements).

The commorientes rule applies to all succession — not just spouses. It also interacts with non-probate assets (life insurance, pensions, joint accounts) in specific ways: (1) NON-SPOUSES IN A COMMON DISASTER: the LPA s.184 older-dies-first presumption applies regardless of the relationship between the deceased persons. Parent and child, business partners, siblings — in every case, the older is presumed to die first. Example: a parent (aged 70) and child (aged 45) die in a plane crash. The parent is presumed to die first. The child is deemed to have briefly survived. The parent's estate (including gifts to the child in the will) passes to the child's estate — then to the child's own beneficiaries. If the child had no will, intestacy governs the child's estate; (2) JOINT TENANCY AND THE SURVIVORSHIP RULE: jointly tenanted property (a house owned as joint tenants, a joint bank account) passes by survivorship to the surviving joint owner. If both joint tenants die simultaneously, LPA s.184 applies — the older is deemed to die first, so the younger is briefly the sole owner. The property then forms part of the younger's estate and passes under their will or intestacy; (3) TENANCY IN COMMON: does not pass by survivorship. Each owner's share forms part of their own estate and passes under their will or intestacy independently. No commorientes issue for the shared interest; (4) LIFE INSURANCE — NOMINATION OF BENEFICIARY: where the insured and the nominated beneficiary die simultaneously, the insurer will look at whether the nominated beneficiary survived. If both died in the same accident and the order cannot be established, the LPA s.184 presumption determines whether the nomination succeeds. Most insurers have their own policy terms for simultaneous death — usually the proceeds fall to the insured's estate if the nominee does not survive by 30 days; (5) PENSION DEATH BENEFITS: pension trustees exercise discretion over death benefits. The trustee's decision is not governed by LPA s.184 — trustees can choose to pay to any nominated beneficiary or dependant, regardless of the order of deaths. A pension trustee who is satisfied that both the pension member and the nominated beneficiary died simultaneously will typically distribute to the next eligible dependant; (6) PRACTICAL ADVICE: (a) include a 30-day survivorship clause in every will; (b) review life insurance nominations — include contingent nominations ('if my wife fails to survive me by 30 days, to my children equally'); (c) update pension expression of wishes forms to include contingent nominations; (d) consider the impact of joint tenancy on commorientes (consider severing the joint tenancy to a tenancy in common where each share can be individually directed by will).