Indexation clause

An indexation clause is a contractual provision that specifies how tariffs or fees are periodically adjusted to a price index, usually the Dutch CBS Consumer Price Index (CPI) or an industry-specific series. The clause defines the reference date, the publication date of the index figure, and the logic for applying it to invoicing. In practice, application errors are common: the wrong series, a missed round, or a late application compounds exponentially into every subsequent year. Without line-level control, the error stays invisible until an external party notices. See also: Solution — Revenue leakage.