Overall mortality rates in England and Wales in the first half of 2026 were lower than in any previous first half of the year, the Continuous Mortality Investigation has found. How should defined benefit trustees factor potentially rising longevity risk into their endgame decisions?

Very low mortality was seen across both women and men in the first half of the year, the CMI said. 

“Mortality for the first half of the year is at record lows in 2026 for all age groups considered in the mortality monitor, helped by continuing lower flu and pneumonia deaths,” said Steve Bale, who chairs the CMI Mortality Projections Committee.  

About 40,300 deaths involved flu or pneumonia, below the range of 47,700 to 51,500 the CMI observed in the first halves of 2023 to 2025. Deaths involving Covid-19 continued to fall, with only about 800 registered this year, much lower than the 11,700, 5,300 and 2,300 seen in the first halves of 2023, 2024 and 2025.   

The lighter mortality experience is a reminder that longevity risk has not gone away – and could be re-emerging just as DB trustees are making decisions about endgames and surplus, said Laura McLaren, head of DB scheme actuary services at Hymans Robertson.  

While many schemes can manage downward pressure on funding levels given their current strong positions, even relatively small assumption changes can affect the size of surplus, the affordability of discretionary benefits and the timing or attractiveness of buyout, she noted. 

  

“The challenge is not that mortality assumptions are overly sensitive to a single year's experience – the CMI model is specifically designed to smooth short-term volatility – but that there remains considerable uncertainty around the long-term trajectory of post-pandemic mortality. Whether recent low mortality represents a temporary fluctuation or the start of a more sustained trend is still unclear,” McLaren pointed out.  

 

There are a wide range of plausible future outcomes given recent experience and the effects of climate change, healthcare pressures, medical advances and the legacy of the pandemic, which could include “more extreme longevity scenarios that may not be captured by a focus on central assumptions alone”, she said. 

 

Average population assumptions need to be adapted to the specific scheme population’s profile, but even this needs to be updated as profiles can change over time. McLaren highlighted that as schemes run on and memberships diminish, longevity risk can become more concentrated and skewed towards dependants.

  

“Trustees and sponsors should stress test their longevity assumptions alongside their wider endgame planning. For larger schemes considering run-on, longevity swaps may remain an important tool where investment risk is well controlled, but longevity risk is the main remaining unhedged exposure,” McLaren said. “More broadly, robust scenario testing can help schemes understand how resilient their funding and surplus plans are if members live longer than expected.”

Hymans Robertson published a paper on Thursday, ‘DB endgames: state of the nation’, which suggests that increased complexity of endgame decisions from uncertainty around the use of surpluses, regulatory detail and decision-making processes continues to slow progress. The consultancy makes the case for sponsors and trustees to be aligned on long-term objectives.