From 1990 to 1996, this variable is part of the Family Resources supplement that provides information on individuals' health benefits, amount of coverage and income received from employment, welfare benefits, public assistance, and savings.

Questions in the Family Resources supplement are different from those in the core survey in terms of the content and the treatment of missing data. Questions in the Family Resources were normally asked of the month prior to the interview while the core survey asked of the last calendar year. All missing data in the Family Resources supplement were imputed by NHIS. Users can refer to the imputation flag variables JOBMOFLAG and JOBSELFMOFL to identify persons with imputed data.

From 1990 to 1992, users can use JOBMOFLAG to identify persons who worked for at least one employer last month and whose information on the number of working months was imputed. From 1993 to 1996, users should use JOBMOFLAG to identify persons with imputed data who exclusively worked for an employer last month and JOBSELFMOFL to identify those with imputed data who worked for an employer and were also self-employed last month.