Rob Kent-Smith to Grant Fitzner: Compliance review of Household Cost Indices 

Dear Grant,

Compliance review of Household Cost Indices   

We have completed our compliance review of the Household Cost Indices (HCIs) against the Code of Practice for Statistics.  We decided to conduct this review given the user interest in the HCIs. It informs further developments and provides direction on the steps needed to achieve stronger compliance with the Code. 

ONS has developed the Household Cost Indices with careful consideration of methods and regular, positive user engagement. The development and regular publication of these statistics represent important steps in meeting the user need for an inflation measure which capture more of the direct costs households face, and can be broken down by household type. However, the publication of these statistics on a lag relative to other consumer price statistics brings its own challenges, and some errors observed in 2025 indicate a need for further quality improvements.

Our report identifies three recommendations for ONS to take forwards for these official statistics in development. ONS should continue to pursue quality improvements to calculation and the production process of the statistics; explore the feasibility of aligning the publication with other inflation statistics; and improve the transparency and the accessibility of the statistics to non-expert users, while also improving navigability between different technical information for more-expert users.

Finally, and more broadly, the next few years look set to be important for these statistics and ONS should ensure it has the capacity to continue developing these statistics, including by addressing the recommendations of this report. We expect ONS to provide a progress update every 6 months during the next two years.

We would like to thank your team for their positive engagement throughout the review.  

I am copying this letter to Michael Hardie, Deputy Director, Prices and Chris Payne, Assistant Deputy Director, Head of Consumer Prices Data and Methods. 

Yours sincerely,

Rob Kent-Smith

Deputy Head of the Office for Statistics Regulation