The Continuous Mortality Investigation (CMI) of the UK Actuarial Profession has released the latest annual version of its mortality projections model CMI 2025. The model projects the path for future mortality rates and is used by most defined benefit (DB) pension schemes when setting assumptions.
Summary
The CMI has undertaken a ‘business-as-usual’ update, adding in the latest year’s data but not making any significant changes to the structure of the model. Compared with last year’s model, CMI_2025 increases life expectancy for males and females at most ages by around 1 to 2 months. The overall impact on a DB pension scheme will vary depending on the age profile of its membership but scheme liabilities will generally increase in value by around 0.5% for schemes adopting the model in place of CMI_2024.
The detail
The CMI_2025 model sees 2025 data for England and Wales incorporated into the model for the first time. Average England and Wales mortality rates in 2025 were the lowest on record, being slightly lower than the previous best year, 2024. CMI_2025 reflects this and gives an overall more positive outlook for longevity than last year’s model, which itself was more positive than the preceding year’s model.
A prolonged slowdown in population mortality rate improvements from 2011, and the subsequent COVID-19 pandemic, caused life expectancies and pension scheme liabilities to steadily decrease. However, the CMI_2025 model marks the second consecutive year where life expectancies have risen.
As with last year’s model update, the detail underneath the headline figures reveals a varied picture – especially when looking at different age bands. In particular, mortality for male adults aged between 20-59 barely improved over 2025 relative to 2024 and is still higher than before the pandemic. Life expectancy under the CMI_2025 model is also still some way behind CMI model predictions made in the early 2010s before the slowdown in UK longevity improvements took hold.
For DB pension schemes, the adoption of CMI_2025 instead of CMI_2024 may lead to a small increase in liability values. Similarly, a small increase is also likely when comparing CMI_2025 with CMI_2022, which many schemes undertaking triennial valuations this year will have adopted for their last valuation.
The following table, from CMI’s Working Paper 211, highlights how the percentage change in life expectancy varies by age when moving from CMI_2024 to CMI_2025. Further details on the parameters used in this comparison are provided within the Working Paper.
| Male | Female | |
|---|---|---|
| Age 25 | +0.2% | +0.2% |
| Age 45 | +0.3% | +0.3% |
| Age 65 | +0.7% | +0.5% |
| Age 75 | +0.6% | +0.5% |
| Age 85 | +0.2% | +0.3% |
