The Consumer Price Index (CPI) is a key economic indicator that serves as an important measure of inflation and changes in the cost of living over time. It is used by a wide range of stakeholders, including policymakers, businesses and households. Given the critical role of the CPI in economic analysis and decision-making, it is essential that national statistical offices compile and publish high-quality CPI series that meet user needs.

This Guide recommends methods and practices for implementing changes in the classification of goods and services in the CPI. It complements the 2020 CPI Manual by presenting detailed guidance and examples of good practices for implementing classification changes in the CPI. Compilers should continue to refer to the CPI Manual as the definitive reference for CPI compilation.

Given the significant update of the Classification of Individual Consumption according to Purpose (COICOP) adopted in 2018, the Guide focuses on the changeover to COICOP 2018. However, the methods and practices presented apply equally well where other classifications are used.