Each year with the release of the January CPI, seasonal adjustment factors are recalculated to reflect price movements from the just-completed calendar year. This routine annual recalculation may result in revisions to seasonally adjusted indexes for the previous 5 years. Recalculated seasonally adjusted indexes as well as recalculated seasonal adjustment factors for the period January 2016 through December 2020 were made available on Monday, February 8, 2021. A file showing the series receiving intervention analysis seasonal adjustment on 2020 data due to the impacts of the COVID-19 pandemic is available on this page. Additional information about the pandemic impact on seasonal adjustment is available on our Effects of COVID-19 Pandemic and Response’ on the Consumer Price Index webpage.
The Consumer Price Index (CPI) produces both unadjusted and seasonally adjusted data. Seasonally adjusted data are computed using seasonal factors derived by the X-13ARIMA-SEATS Seasonal Adjustment Method. These factors are updated with the release of January data in February and reflect price movements from the previous calendar year. The new factors are used to revise the previous 5 years of seasonally adjusted data; older seasonally adjusted indexes are considered to be final.
Last Modified Date: February 8, 2021