This paper examines subannual health insurance coverage estimates in the Current Population Survey Annual Social and Economic Supplement (CPS ASEC). Analyzing subannual coverage for children under 19 and working-age adults aged 19 to 64 during the 2017 and 2018 calendar years, this paper compares estimates from the CPS ASEC with the Medical Expenditure Panel Study Household Component (MEPS-HC) and the Survey of Income and Program Participation (SIPP).