Set ddata Consumer price inflation time series

17 September 2025

Following a minor correction of the method used to impute missing seasonal items last month, a further minor correction has been made to resolve a residual issue with three seasonal items, affecting lower-level aggregates in July 2025 data only. This has no impact on the headline Consumer Prices Index (CPI) or the Consumer Prices Index including owner occupiers’ housing costs (CPIH) annual growth rates. The Retail Prices Index (RPI) is also unaffected. 

In line with the Office for National Statistics (ONS) consumer prices revisions and correction of errors policy, we have not corrected the indices for July 2025. However, we have corrected the error in the August 2025 published indices. 

This error is isolated to the imputation process of three seasonal items in July 2025 only and has been identified as part of a programme of work to modernise the production of consumer prices inflation. This includes building a more robust production system as we move towards incorporating scanner data in 2026.