Longevity Risk: Will Your Pension Outlast You?

01 What longevity risk actually is

Longevity risk is the risk that you outlive your money. It is the one retirement risk that gets worse the better things go: live a long, healthy life and you face more years to fund, more inflation to absorb, and a higher chance of late-life care costs.

It is also the hardest to recover from. A market crash announces itself and is often followed by a rebound you live to see. Longevity gives no signal at all — by the time you know you have underestimated it, you are in your late eighties with a depleted pot and no capacity to earn, and every option that was available at 65 has closed.

That asymmetry is what makes it worth over-planning for. Overestimating your lifespan leaves money behind, which becomes a bequest or a margin of comfort. Underestimating it produces a specific, irreversible failure at the point of maximum vulnerability. Those two errors are not equivalent and should not be planned for as though they are.

The good news, developed below, is that insuring against it is cheaper than the fear suggests — because money needed thirty years out is heavily discounted by the returns the pot earns in the meantime, and because most of the protection can be bought with income rather than capital.

Life expectancy at birth is the figure usually quoted, and it is the wrong one for anyone reading this. Having already reached 65, you have survived everything that removed people earlier, so your remaining expectancy is materially longer than the headline number — and planning to the headline is planning to run out about half the time.

Source: GOV.UK — Plan your retirement income

02 Plan to a percentile, not an average

Here is the statistical trap. "Life expectancy" is an average, and an average has half the population on each side. Build a plan to last exactly that long and you have built one with roughly even odds of failing.

It is worse than that, because the figure people quote is usually life expectancy at birth, which understates the position for anyone already at 65. Having survived to 65 you have avoided every cause of death that removed people before it, and your remaining expectancy is longer than the headline number implies. The relevant statistic is expectancy at your current age, not at birth, and the two differ by years.

The fix is to plan to a percentile rather than an average — the age perhaps one in ten of your cohort reaches, commonly the mid to late nineties. That turns an even-odds plan into one that fails rarely.

The cost of doing so is smaller than it sounds, and the next chapter shows why: money needed thirty years out is heavily discounted by the return the pot earns in the meantime, so extending a plan from 88 to 96 does not add anything like a proportional amount of capital.

Source: ONS — Life expectancy calculator

03 Couples: the horizon is the last survivor

For a couple the horizon stretches further, because the money has to support whoever lives longest rather than either of them individually.

Two people who each have a decent chance of reaching their early nineties have, between them, a materially higher chance that one sees the late nineties. Joint survivorship is the number that matters and it is always longer than either expectancy alone.

Planning to the first death leaves the survivor exposed, and the exposure is worse than it looks because household costs do not halve when one partner dies. Housing, heating, council tax, insurance and maintenance are largely fixed; a widow or widower typically needs around two-thirds of the couple's spending, not half.

The income side frequently falls faster than that. One State Pension stops. A defined-benefit pension usually continues at 50% or 60% for a spouse, and sometimes at nothing. An annuity bought on a single life stops entirely.

That mismatch — costs falling to about two-thirds while income can fall to half or less — is the specific risk a couple's plan needs to test. The question worth asking explicitly is: if I died next year, what income would my partner actually have? It is a five-minute check, and it changes annuity choices and pension nominations more often than any projection does.

04 What extra years cost your pot

Extra years aren't free, but they cost less than the fear suggests, because each future pound is discounted by the return your pot still earns. The tool below shows the pot needed to fund a level real income for a set number of years, and — in the second panel — the pot if you live eight years longer than planned. The gap between them is your personal "longevity premium": the extra capital that buys insurance against the long tail.

Notice how much smaller the second jump is than the first pile of capital — because at a positive real return, money decades away is heavily discounted. Longevity insurance is real, but it's cheaper than the headline fear, and most of it can be bought with income rather than capital.

05 Lifetime income is longevity insurance

The cleanest defence against outliving your money is income that's contractually for life. The State Pension is the best example almost everyone owns: paid until you die, rising each year under the triple lock, and completely indifferent to how long you live. An annuity does the same with private money, pooling longevity across thousands of buyers so it can pay more than a cautious drawdown rate while removing run-out risk entirely. Cover your essential spending with these lifetime sources and the longevity question stops being existential — your pot is then funding wants, not survival, and a bad run of markets at 95 is an inconvenience rather than a catastrophe.

06 Building a plan that can't run out

A robust plan stacks three layers, and the order is what makes it robust.

First, floor the essentials with lifetime, inflation-linked income. The State Pension does this for most people; annuitising enough private money to cover the remaining basics extends the floor. Once essentials are covered by income that cannot run out and rises with prices, longevity stops being an existential risk and becomes a question about comfort.

Second, plan the flexible pot to a percentile rather than an average, with a withdrawal rate that respects the horizon — nearer 3.5% than 4% for a long retirement, and lower again for someone stopping in their fifties.

Third, keep genuine flexibility in discretionary spending and decide in advance what gets trimmed in a poor year. That layer costs nothing and does more for the survival of the portfolio than the other two.

Each handles a failure the others do not. The floor handles living to 100. The rate handles an ordinary market. The flexibility handles a bad sequence. Building two of the three leaves a specific gap, and it is better to know which one than to find out at 90.

Review it every few years with real numbers, because your health, your partner's position and the size of the pot will all differ from what you assumed at 65.

07 What each layer of the plan actually covers

Three layers, three different jobs. The common mistake is building two and assuming the third is covered.

Note which layer is free. Spending flexibility costs nothing and is the one most often left out, because it requires a decision rather than a purchase.

Source: MoneyHelper — Guaranteed retirement income (annuities)