Nonprofit hospitals provide charity care to financially disadvantaged patients according to their self-designed eligibility policies. The Affordable Care Act may have prompted nonprofit hospitals to adopt more generous eligibility policies, but no prior research has examined the longitudinal trend. The expansion of Medicaid coverage in many states has been found to reduce charity care provision, but it is unclear whether the change in charity care eligibility policies differed between Medicaid expansion and nonexpansion states. Using mandatory tax filings, we found that both hospitals in Medicaid expansion states and hospital in nonexpansion states adopted more generous eligibility policies in 2018 than in 2010, but the change was greater in the former for discounted charity care; while the former provided less charity care regardless of their policy changes, the latter provided more when their policies became more generous. This study has implications for policy discussions on the justification of nonprofit hospitals’ tax-exempt status.