The maths annuity providers hope you won't do
A 65-year-old with £250,000 buying a level single-life annuity today gets roughly £19,600 per year — that's the best available rate at approximately 7.84% from providers like Scottish Widows. Sounds reasonable until you account for inflation.
At the Bank of England's 2% inflation target, that £19,600 buys you the equivalent of £13,200 in today's money after 20 years. After 25 years, it's worth £12,100. Your income doesn't shrink in nominal terms, but your purchasing power collapses.
You could buy an RPI-linked annuity instead. The best rate for a 65-year-old is around 5.68%, giving you £14,200 in year one — £5,400 less than the level annuity from day one. You're paying £5,400 per year for inflation protection you could manage yourself through a diversified portfolio.
The drawdown starting income looks lower at a 4% withdrawal rate — £10,000 from a £250,000 pot. But that pot is still invested, still growing, and still yours. Compare this with the guaranteed returns on gilts — currently yielding around 4.43% — and the flexibility advantage becomes even clearer.