Better your money outlives you than vice versa.
When people question why we plan to age 100, they are rarely being unrealistic. More often, they are using the generation above them as a reference point.
Parents who died in their late 70s or early 80s (or younger) feel like a reasonable guide. Friends who did not enjoy long retirements reinforce the impression. It is a natural shortcut.
It is also a misleading one.
A Moving Target
Life expectancy is not fixed. Each generation experiences different medicine, working lives, living standards and health behaviours. Planning based on yesterday’s outcomes quietly assumes none of that matters.
The Office for National Statistics captures this through cohort life expectancy, which looks forward as well as back. It allows for expected improvements in mortality rather than relying solely on historic averages. This has been updated in the past month.
The latest ONS life tables and projections show that people reaching retirement today have a strong chance of living into their late 80s and 90s. The gap between men and women has narrowed considerably. Among our own clients, men in their 90s are now routine rather than noteworthy.
Averages, however, are not the point. The more relevant observation is that a meaningful minority will live much longer than the average. The ONS even provides a life expectancy calculator (based on older, but still useful, data) that includes the probability of reaching age 100. Longevity risk is real, and for a significant minority, a retirement lasting 30 years or more is entirely plausible.
Two Lives, One Plan
When we plan for two people, longevity matters more.
A household plan does not need both partners to live a long life for the maths to become challenging. It only needs one. The plan must cope with whichever partner lives longest, often on a reduced income (state pension increases for the survivor less commonly these days) and sometimes with rising support or care costs.
This is why, in practice, we so often see plans where one partner reaches their early or mid-90s. From a planning perspective, this is not a remote possibility. It is an outcome that needs to be assumed and absorbed.
Not the Average Retiree
The national statistics describe everyone. Our clients are not everyone.
They tend to be healthier, wealthier and financially more secure than average. All of those characteristics are associated, statistically, with longer life expectancy.
That does not guarantee a long life. It does mean that planning purely on population averages is likely to understate the risk of a long retirement for people in our position.
It also explains a familiar pattern in conversations: people underestimate how long they might live, while quietly assuming their money will somehow stretch further than the arithmetic suggests.
Why We Stop at 100
There is a useful comparison here with planning done for the Court of Protection in deputyship cases.
In that context, advisers are often required to model cashflows to age 110. The reasoning is clear. The court must be satisfied that funds will last for the rest of a person’s life, without relying on engagement, judgement or behavioural change.
For most private clients, however, modelling to 110 creates a different problem. It strains credibility. Once assumptions feel implausible, people disengage. The plan stops guiding real decisions.
I think planning to age 100 strikes a balance. It reflects modern longevity evidence, captures the genuine risk of a long life, and remains believable enough for clients to act on. That credibility matters. A plan only works if people are prepared to live by it.
Why 90 Is Not Enough
Planning to 90 is not cautious. It is optimistic.
It assumes average outcomes, ignores the effect of two lives rather than one, and leaves little margin for error. If someone outlives a plan built to 90, the shortfall appears precisely when flexibility is lowest.
By contrast, planning to 100 is not a forecast. It is a stress-test. If a plan works to 100, it is far more likely to work at 92 or 88. It gives clarity about what can be spent now and confidence that later life is not being quietly gambled away.
The Risk Worth Avoiding
If someone dies earlier than expected, unused assets usually pass to a surviving partner or to family. That outcome may not have been intended, but it is rarely financially destabilising.
Living longer than planned for is different. When that happens late in life, there is far less room to adapt, and the consequences are harder to reverse.
This is why we plan the way we do.
In Summary
We plan to age 100 because:
- life expectancy for today’s retirees is higher than many assume
- using the previous generation as a guide is unreliable
- couples only need one long life for longevity risk to matter
- our clients are typically healthier and wealthier than average
- planning must be both prudent and believable
Or, more simply:
Better your money outlives you than vice versa.
