Indexation

Indexation is the practice of linking a payment, price, threshold or contract value to a price index so that it rises automatically with inflation. Common examples are pensions and social benefits uprated by the Consumer Price Index (CPI), wages tied to living costs, inflation-linked government bonds, rents that rise with a price index, and income-tax brackets adjusted each year. The aim is to keep the value of the payment constant in real terms instead of letting inflation erode it.

Indexation is the institutional answer to money illusion and to the arbitrary transfers inflation causes between borrowers and lenders, workers and employers, and taxpayers and governments. It is closely related to a cost-of-living adjustment (COLA), which is one specific form. Economists debate whether widespread indexation stabilises an economy or makes inflation harder to stop.

Imagine agreeing to pay a friend a sack of rice every year rather than a fixed sum of money. Whatever happens to prices, the friend still gets the same amount of food. Indexation does something similar with money: it promises "the same buying power" rather than "the same number on the cheque".

If a pension is indexed and prices rise 3% this year, next year's pension rises 3% too, so the pensioner can still afford the same groceries. Without indexation, a fixed pension slowly shrinks in value year after year, even though the number printed on it never changes.

An indexed payment is scaled by the ratio of the current index to the index at a base date:

• $A_t$ is the indexed amount at time $t$.
• $A_0$ is the original amount at the base date.
• $I_t$ and $I_0$ are the values of the chosen price index at time $t$ and at the base date.

Worked example: a benefit of 1,000 a month was set when the index stood at 200. If the index is now 214, the indexed benefit is $1{,}000 \times 214 \div 200 = 1{,}070$, a 7% rise that matches the 7% increase in prices.

• Pensions and benefits. US Social Security benefits have been automatically adjusted each year since 1975 using the CPI-W; the adjustment for 2026 was 2.8%. The UK state pension is uprated under the "triple lock" by the highest of earnings growth, CPI inflation or 2.5%.
• Government bonds. The UK began issuing index-linked gilts in 1981, and the US Treasury introduced Treasury Inflation-Protected Securities (TIPS) in 1997; their principal rises with the CPI. Many other governments, including France, Italy, Japan, Brazil and India, have issued similar government bonds.
• Taxes. US federal income-tax brackets and the standard deduction have been indexed to inflation since 1985. Where thresholds are frozen rather than indexed, inflation pushes people into higher bands, an effect known as fiscal drag, which raises the effective marginal tax rate on many earners.
• Wages. Belgium and Luxembourg have long-standing systems that automatically raise most wages in line with a price index. Many collective agreements negotiated by a trade union include COLA clauses, and some countries index the minimum wage.
• Contracts and loans. Commercial leases often link rent to an index. In Chile, the Unidad de Fomento (UF), an inflation-indexed unit of account, is widely used for mortgages and long-term contracts.

Indexation protects people on fixed incomes, especially retirees, from losing purchasing power. It reduces the uncertainty of long-term contracts, which can lower the inflation premium lenders demand. Inflation-linked bonds also give policymakers a market-based reading of expected inflation: the gap between nominal and indexed bond yields, the "breakeven" rate, is watched by central banks pursuing inflation targeting. For governments, indexed tax brackets prevent unlegislated tax rises.

The main concern is that widespread indexation makes inflation self-perpetuating. If wages, rents and prices all follow last year's inflation automatically, a one-off price shock is passed through the economy and can feed a wage-price spiral. Brazil's experience before the 1994 Real Plan, when pervasive indexation kept very high inflation going, is often cited; part of that plan's design was to break the link. Other criticisms include:

• Index choice. Results depend on which index is used. The UK moved its inflation target from an RPI-based measure to the CPI in 2003 and switched most benefit uprating from the Retail Prices Index to the CPI from 2011, partly because the RPI's formula was judged to overstate inflation.
• Measurement issues. Quality adjustments such as hedonic adjustment affect how much indexed payments rise.
• Fiscal cost. Indexed benefits and debt raise government spending automatically when inflation jumps, adding to national debt service costs.
• Lags. Indexation usually uses past inflation, so recipients lose ground while prices are rising fast and catch up only later.

• U.S. Social Security Administration: Cost-of-Living Adjustment
• TreasuryDirect: Treasury Inflation-Protected Securities (TIPS)