After the release of the 2021 American Community Survey (ACS) data products, the Census Bureau identified a processing error in the Weeks Worked data among respondents who did not report working all 52 weeks in the previous 12 months. The error impacted data collected via mail questionnaires for a small number of responses in 2019 and all mail responses in 2020 and 2021. As such, the error was present in 2019, 2020, and 2021 1-year and 5-year data products and Public Use Microdata Sample (PUMS) files. 

The error had only a nominal impact on final estimates for employment, income, poverty, and related topics. Additional details about the nature of the processing error and the extent of its effects are described in a working paper. For more information, please refer to the Weeks Worked Error Impact Assessment Report: 2021 American Community Survey.

Despite the small impact, revised data for 2021 will be used to create the 2022 and later 5-year ACS data. However, 2019 and 2020 data were not reprocessed due to a smaller number of affected cases and processing limitations, respectively.