In 2019, the American Community Survey (ACS) added questions that can be used to produce estimates of the population with subsidized Marketplace health insurance coverage. As the largest federal household survey, the ACS is the principal source of health insurance coverage information for state and sub-state geographies, as well as for smaller populations. This memo (1) provides background on the new question, (2) describes key features of the data universe, (3) summarizes the imputation and logical assignment process for missing, incomplete, and inconsistent information, and (4) presents a selection of estimates.  Along with a large sample size, the ACS includes a variety of social, demographic, and housing information.  As a result, the new ACS subsidized Marketplace coverage estimates present an opportunity for policymakers and researchers to more fully understand the population.