Affordable Care Act ACA

President Barack Obama signed the Patient Protection and Affordable Care Act on March 23, 2010, after it passed Congress with only Democratic votes. It barred insurers from denying coverage or charging more because of pre-existing conditions, let young adults stay on a parent's plan until age 26, required plans to cover essential benefits and free preventive care, and created marketplaces, such as HealthCare.gov, where people can buy coverage with income-based tax credits.

The law survived major court challenges. In NFIB v. Sebelius in 2012 the Supreme Court upheld the requirement to have insurance as a tax but made the Medicaid expansion optional, in King v. Burwell in 2015 it upheld tax credits in all states, in California v. Texas in 2021 it rejected a challenge after Congress set the mandate penalty to zero in 2017, and in Kennedy v. Braidwood Management in 2025 it upheld the system for choosing free preventive services. The uninsured rate fell from about 16 percent in 2010 to a record low near 8 percent in 2023.

Larger tax credits passed in 2021 helped marketplace enrollment reach a record 24.2 million in 2025, but they expired at the end of 2025 after Congress did not extend them, and enrollment fell to about 23 million for 2026 as premiums rose for many buyers. Supporters say the law made coverage available to millions and should be strengthened. Critics say it raised premiums, limited choices, and relies on costly subsidies, and they favor more state control and cheaper, less regulated plans.