Longevity risk - the risk that members live longer than assumed - is one of the defining challenges for UK defined benefit (DB) pension schemes. Unlike investment risk, it cannot be diversified away within a scheme: if longevity improves across the population, every pensioner liability extends together. With UK DB schemes largely closed and maturing, and funding positions transformed by higher interest rates, managing longevity risk has moved to the centre of endgame strategy.
Measuring the risk
Longevity risk has two layers. Base mortality risk is the risk of misestimating current mortality rates for a scheme's specific membership - socio-economic mix, postcode, pension size and industry all matter, which is why scheme-specific experience analysis and postcode-based mortality models are standard. Improvement risk is the deeper uncertainty: how quickly mortality rates will fall in future. UK practice leans on the CMI projection model as a common language, but the true range of outcomes - shaped by medical advances, lifestyle trends, and shocks such as the pandemic - is wide. A modest change in assumed improvements can move liabilities by several percent, which for a large scheme is a material sum.
The risk transfer toolkit
The UK hosts the world's deepest longevity risk transfer market, offering trustees a spectrum of solutions. Buy-ins - bulk annuity policies held as scheme assets covering a subset of liabilities - remove longevity, investment and inflation risk for the covered members while keeping the scheme intact. Buyouts go further, transferring liabilities to an insurer entirely and typically preceding wind-up. Longevity swaps isolate the longevity component alone: the scheme pays a fixed premium leg and receives payments reflecting actual member survival, converting uncertain longevity into a known cost while retaining investment strategy freedom. Swaps have historically suited very large pensioner populations, though structures have become more accessible over time.
A seller's market meets a maturing demand
Improved funding levels - driven by the rise in gilt yields - have brought buyout within reach for many schemes years earlier than expected, producing heavy demand for insurer capacity. That demand queue has consequences: insurers can be selective, data quality and preparation determine which schemes transact on good terms, and alternatives - superfunds, captive-backed structures and run-on strategies with surplus extraction - have entered the conversation for schemes weighing whether full insurance is the right destination at all.
What trustees and sponsors should do
First, understand the exposure: quantify longevity risk alongside investment risk in the scheme's journey plan rather than treating it as a residual. Second, invest in data: clean, complete member data and codified benefit specifications are the entry ticket to competitive insurer pricing. Third, sequence deliberately: partial buy-ins, phased by member cohort, can de-risk progressively while retaining flexibility. Fourth, weigh run-on honestly: for well-funded schemes with strong covenants, running on and distributing surplus may create value - but only with a clear-eyed view of the longevity tail being retained.
Conclusion
Longevity risk rewards early, well-prepared action. Schemes that measure the risk properly, prepare their data, and choose the transfer route matched to their endgame will convert one of the pension world's deepest uncertainties into a planned, priced outcome - and that is what good stewardship of members' benefits looks like.