The Congressional Budget Office developed its Health Insurance Simulation Model (HISIM) in 2002 to model the effects of health insurance proposals on coverage levels. HISIM uses microdata to simulate individual and family coverage decisions and estimate the budgetary impacts of proposals over 10 years. It factors in economic forecasts and is regularly updated based on new data and research. HISIM models coverage through employers, Medicaid, ACA marketplaces, and the uninsured to help CBO prepare baseline budgets and estimate costs of new policies.