The quiet risk most people underestimate
In brief: Inflation reduces the purchasing power of money over time. A 30-year retirement means the spending needs you have today cost significantly more by the end — and income sources that do not rise with prices gradually buy less. At 2.5% inflation, prices roughly double over 28 years.
Most people entering retirement think carefully about running out of money. Fewer think carefully about a subtler risk: that the money they have buys less and less as the years pass.
Inflation does not announce itself. There is no single moment when your income suddenly feels inadequate. Instead, it is gradual — groceries a little more expensive, utility bills a little higher, holidays a little further out of reach. Over a decade or two, those small annual increases compound into a significant reduction in what your money can actually do.
For a shorter working career, inflation is a background consideration. For a 25 or 30-year retirement, it is one of the most consequential factors in the projection.
What inflation is, and how it compounds
Inflation is the rate at which prices rise over time. When inflation runs at 2.5% per year, something that costs £1,000 today costs approximately £1,025 next year — and roughly £2,000 in 28 years.
The compounding effect is what gives inflation its force over long retirements. Each year’s price increase is applied to an already-elevated price level, not to the original. This is why the erosion accelerates: the same percentage applies to a larger base each year.
| Annual inflation | Years for prices to double |
|---|---|
| 2.0% | ~35 years |
| 2.5% | ~28 years |
| 3.0% | ~24 years |
| 4.0% | ~18 years |
If you retire at 60 with a 30-year horizon and inflation averages 2.5%, prices at the end of your retirement will be roughly two and a half times higher than when you started. Your income needs to grow with them, or your standard of living falls.
Real vs nominal: the number and what it buys
When looking at any financial projection, it is worth understanding whether the figures are expressed in nominal or real terms.
Nominal figures are the actual pound amounts at the time — the number on the statement. A pension pot that grows from £200,000 to £350,000 over 15 years looks like a clear gain in nominal terms.
Real figures adjust for inflation and express everything in today’s purchasing power. If prices have risen 40% over those same 15 years, that £350,000 is only worth about £250,000 in real terms — a much more modest gain.
Real-terms projections are easier to interpret because spending targets stay constant. If you need £30,000 per year in today’s money, that figure remains £30,000 throughout the projection — rather than climbing to £50,000 or £60,000 in nominal terms to represent the same lifestyle.
FutureClear shows all projections in real terms by default. The growth rates you enter are real rates (after inflation). This means a projected portfolio balance of £400,000 at age 80 means £400,000 of today’s buying power — you do not need to mentally discount for inflation.
The impact on income that does not keep pace
Not all retirement income rises with inflation. Income sources that are fixed in nominal terms — or that increase more slowly than inflation — lose real value every year.
Level annuities are the clearest example. A level annuity of £10,000 per year pays £10,000 in year one, year ten, and year twenty-five. The nominal figure never changes — but at 2.5% inflation, by year 28 that £10,000 buys roughly half of what it did when you first received it. Level annuities pay a higher initial income than inflation-linked equivalents, but the real value declines with each passing year.
DB pensions with capped escalation can face a similar issue. A defined benefit pension that increases by a maximum of 2.5% per year holds its real value when inflation is at or below the cap — but if inflation runs above it, the real income gradually falls.
Fixed rental income from property — if not reviewed regularly — can also fall behind inflation over time.
Whether a level or capped income is appropriate depends entirely on your circumstances. But it is worth understanding the real-terms trajectory, not just the nominal figure at inception.
Income sources that keep pace
Some income sources are explicitly linked to inflation or have historically grown ahead of it.
The State Pension currently rises each year by the highest of earnings growth, CPI inflation, or 2.5% — commonly called the triple lock. In real terms, this means State Pension income has broadly held or increased its purchasing power since the triple lock was introduced. Whether the triple lock continues in its current form is uncertain and a matter of ongoing political debate, but as currently legislated, State Pension income tracks inflation.
CPI-linked DB pensions rise with the Consumer Prices Index and maintain their purchasing power by design. In FutureClear’s real-terms view, a fully CPI-linked income appears as a flat line — unchanged year to year. That is correct: flat in real terms means it keeps pace with prices.
Investment growth in pension drawdown, ISAs, and GIA accounts has historically exceeded inflation over long periods in diversified equity portfolios. This is not guaranteed — market returns vary considerably — but it illustrates why retaining some exposure to growth assets during retirement can provide a natural buffer against inflation eroding your income. See the Investment Returns article for more on how growth assumptions work.
Inflation and cash savings
Cash carries particular inflation risk over long periods. If the interest rate on your savings account is below the prevailing inflation rate, the real value of your cash falls every year — even as the nominal balance increases.
This is not a reason to hold no cash. An emergency fund, a short-term spending buffer, and a near-term drawdown reserve all have legitimate roles in a retirement portfolio. But large, long-term cash holdings in low-interest environments are slowly eroded by inflation. The larger the cash holding relative to your overall assets, and the longer the period, the more significant this drag becomes.
See the Cash Savings article for more detail on how interest rates, inflation drag, and the personal savings allowance interact.
Fiscal drag: the invisible tax increase
There is a related but distinct effect worth understanding: fiscal drag, sometimes called bracket creep.
Income tax thresholds in the UK are currently frozen until at least 2028, with extensions announced to 2031. The personal allowance remains £12,570 and the higher rate threshold stays at £50,270.
As nominal incomes rise with inflation — even when real purchasing power stays the same — more income falls into higher tax bands. A pension income that keeps pace with 3% annual inflation will, after several years of frozen thresholds, have a meaningfully higher proportion taxed at 40% than it did at the start of retirement. The pounds you receive are worth the same in real terms, but a larger share is taken in tax.
This is a real effect, not a hypothetical. The OBR has estimated that freezing thresholds is one of the most significant fiscal tightening measures in recent UK budgets. For retirees drawing down pension income, the combined effect of inflation-driven nominal income growth and static tax thresholds can meaningfully increase the effective tax rate over a long retirement.
FutureClear models tax year by year using the thresholds in place for each year. Where thresholds are legislated as frozen, the projection reflects that. Where future thresholds are uncertain, you can adjust the assumption in the scenario settings.
How FutureClear handles inflation
When you set up a scenario, you choose an inflation assumption. The default is 2.5%, in line with the Bank of England’s target.
All projections are shown in real terms — today’s purchasing power — so your spending targets remain constant and growth figures reflect genuine increases in value rather than just price-level changes.
Growth rates for investment assets are entered as real rates. An investment growth assumption of 4% means 4% above inflation, not 4% in total. If inflation is 2.5%, the implied nominal return would be approximately 6.5%.
Income sources are handled according to their link to inflation. CPI-linked income (such as a fully linked DB pension) appears flat in real terms. Level income (such as a fixed annuity) declines in real terms over time, accurately reflecting its eroding purchasing power. The State Pension uses the triple lock assumption unless you override it.
You can explore the effect of different inflation assumptions by creating multiple scenarios with different rates — for instance, a central case at 2.5%, a higher inflation scenario at 4%, and a lower scenario at 1.5%. Seeing how the outcomes diverge over a 30-year projection gives a clear picture of how much inflation matters to the long-term result.
These projections are for modelling purposes only. They do not constitute financial advice. Tax rules, inflation, and investment returns are uncertain and subject to change. Please consult a qualified financial adviser before making financial decisions.