Inflation-linked bonds offer protection while nominal gilts risk purchasing power

Mechanics of the index ratio

The heavy lifting in a linker is performed by the index ratio. This figure represents today's Retail Prices Index divided by the base index level at the time the bond was issued. If the index has grown from 164 to 406, every payment—both coupons and the final redemption—is multiplied by 2.47. This mechanism creates a disconnect between the nominal units held and the actual cash received. While recent issues might feature tiny nominal coupons of 0.125%, the inflation adjustment ensures the total return accounts for the rising cost of goods.

Debunking the breakeven inflation myth

Investors often confuse breakeven inflation with a loss threshold. A breakeven rate of 3.6% simply identifies the point where a linker matches the return of a conventional bond. Falling below this rate doesn't mean a nominal loss; it signifies an opportunity cost. Linkers also include a risk premium, partly because pension funds and insurers are willing to pay a premium for the certainty of matching inflation-linked liabilities. Furthermore, the shift from RPI to CPIH in 2030 will lower future adjustments for long-dated bonds, a crucial detail for those building ladders beyond the next decade.

Managing the practical reality

On most platforms, the "dirty price" of a linker can be a shock. Unlike conventional bonds, where the difference between clean and dirty prices is minor, a linker's dirty price includes decades of accumulated inflation. An investor might see a clean price of £103 but pay a dirty price of £177. Because the primary return arrives as an inflation-adjusted lump sum at maturity, these assets are better suited for retirement planning and wealth preservation than for generating immediate, predictable cash income.