BOC Census Numident (CNUM)

The Census Numident is a processed version of the Social Security Administration (SSA) Numident ("Numerical Identification System") file. The file contains one record for every social security number (SSN) that has been issued, since 1936. The file contains information such as name, date of birth, gender, race, place of birth, citizenship status and date of death. Information is collected in the process of requesting or updating an SSN.

The original SSA Numident contains all transactions ever recorded against any single SSN. Each entry represents an addition or change to the enumeration information for a given SSN. The Census Numident is created from the SSA Numident transactions by creating a "one best-data record" per SSN file. The Census Numident is a Title 13 dataset containing no SSNs or individual names. The file can be linked to other datasets using Protected Identification Keys (PIKs).

In late 2014, SSA stopped delivering to the Census Bureau many of the new death transactions on the Numident file. This problem was not fixed until 2018. On the research data warehouses, updates are only available in the Numident files from 2019 on. The Numident releases to the data warehouse dated 2015-2018 should be considered to have significant underreporting of deaths. If researchers are using the death variables on the Numident, we recommend that they only use the latest versions. These files contain the personally identifiable information (PII) used for Person Identification Validation System (PVS) processing. Should only be requested by projects that need and are approved to use PII.