Imagine you retire at 65 with a guaranteed monthly pension of £1000. That feels comfortable today. Fast forward 20 years, and because of inflation, each pound buys only half of what it used to. That same £1000 feels tight. This slow loss of value is why many long‑term insurance and pension contracts include indexation – a way to automatically increase benefits so they keep up with the cost of living. In this chapter we explore how that linking works in multiple state models, how to adjust premiums and reserves to keep the contract fair, and where the money for these increases comes from.