I am working on a project where I am gathering income components to create a social welfare measure. I am using the ASEC samples as my data set, including 2019. In gathering data for my project, I noticed that beginning with the 2019 ASEC, the CPS disaggregates the retirement income measures into different variables, and that INCRETIR now records only “income from retirement accounts, and not pension plans or annuities. Retirement account income from 401k, 403b, Roth IRA, regular IRA, KEOGH, and Simplified Employee Pension (SEP) plans.” When I examine the universe of this variable, I notice that the universe is constrained to “Persons age 58+.” I am unable to locate the reasoning for such a restriction and was hoping that someone here could explain this. Given that people choose to retire and draw from retirement income sources at various ages (particularly for defined contribution sources such as 401k accounts), why would the source of this variable be constrained to only persons who are 58 years of age and older? Any insight with documentation would be extremely helpful.