The Census and Statistics Department conducts a Household Expenditure Survey (HES) once every five years to collect up-to-date information on expenditure patterns of households in Hong Kong. The information is used together with data on price movements collected on a monthly basis by the C&SD to compile the monthly Consumer Price Indices (CPIs).

Based on the results of a new round of HES conducted in 2004/05, the CPIs have been rebased. The expenditure ranges and weighting patterns of the CPIs have also been updated. The re-based CPI series have been released on 27 April 2006.