Context: Medicaid expansion has costs and benefits for states. The net impact on a state's budget is a central concern for policy makers debating implementing this provision of the Affordable Care Act. How large is the state-level fiscal impact of expanding Medicaid, and how should it be estimated?

Methods: We use Michigan as a case study for evaluating the state-level fiscal impact of Medicaid expansion, with particular attention to the importance of macroeconomic feedback effects relative to the more straightforward fiscal effects typically estimated by state budget agencies. We combine projections from the state of Michigan's House Fiscal Agency with estimates from a proprietary macroeconomic model to project the state fiscal impact of Michigan's Medicaid expansion through 2021.

Findings: We find that Medicaid expansion in Michigan yields clear fiscal benefits for the state, in the form of savings on other non-Medicaid health programs and increases in revenue from provider taxes and broad-based sales and income taxes through at least 2021. These benefits exceed the state's costs in every year.

Conclusions: While these results are specific to Michigan's budget and economy, our methods could in principle be applied in any state where policy makers seek rigorous evidence on the fiscal impact of Medicaid expansion.