The model documented here builds off of the Urban Institute's base HIPSM, which uses the Current Population Survey (CPS) as its core data set, matched to several other data sets including the Medical Expenditure Panel Survey-Household Component (MEPS-HC), to predict changes in national health insurance coverage and spending under ACA using a micro-simulation modeling approach. To create HIPSM-ACS, we apply the core behavioral estimates coming from base HIPSM to ACS records (using a series HIPSM-estimated imputation models) to exploit the much larger sample size for more precise estimates at the state and sub-state level.