09.12.2025 15:41
The Turkish Statistical Institute will update its inflation calculation system starting from 2023, changing the base year from '2003=100' to '2025=100'. The methodological update of the Consumer Price Index will come into effect in January 2026. With this change, the main expenditure group will increase to 13, while there will be no change in the headline inflation indicators.
A briefing meeting was held at TÜİK regarding the update of the CPI base year and changes to the calculation system. In the meeting, the institution's experts explained the inflation calculation that will change in the new year.
CALCULATION WILL BE ALIGNED WITH THE EU
In line with the decisions of the European Commission, the CPI base year will be updated to "2025=100" in all member countries starting from January 2026. This change will be mandatory for all EU member countries.
The CPI weighting structure will transition to a system where national accounts data is considered the primary source as part of the methodological transformation determined by Eurostat. In the new CPI series, the group-level weights will be derived from national accounts household final consumption expenditure data, reflecting household consumption trends more comprehensively and up-to-date. Lower-level weights will continue to be determined by the household budget survey.
HEADLINE INFLATION INDICATORS WILL NOT CHANGE
The level of the index for the transition from the "2003=100" base year to the "2025=100" base year will be normalized according to the average index of the year 2025. Monthly and annual change rates will remain the same. The inflation rate will not change within any year or month. There will be no changes in the headline inflation indicators for the "2003=100" base year period; only some differences may arise from classification changes in certain sub-indices.
The main expenditure group will increase to 13. Personal care, social protection, and various goods and services will be divided into two main expenditure groups. Insurance and financial services will be included as a new expenditure group in the inflation calculation. Additionally, with the changes made, digital content will be presented as a separate category.
Thanks to multi-source data sets such as tax, production, and sales statistics, informal consumption items will also be reflected in total expenditures.
FIXED TAX RATE AND CPI INDICATOR WILL BE PUBLISHED
In the new year, it is also planned to publish seasonally adjusted CPI indicators on the same day as the CPI.
The CPI indicator will be published with fixed tax rates. The CPI calculated with fixed tax rates will be a complementary indicator that measures only the changes in the net market prices of goods and services, assuming that indirect taxes (VAT, SCT) are held constant.