After decades of trying and despite unanimous opposition from Republicans, President Obama and Democrats passed comprehensive health reform into law in March 2010. The Affordable Care Act will hold insurance companies accountable, lower costs, expand coverage, and improve care for all Americans.

The Patient Protection and Affordable Care Act, often shortened to the Affordable Care Act (ACA) or nicknamed Obamacare, is a United States federal statute enacted by the 111th United States Congress and signed into law by President Barack Obama on March 23, 2010. The term "Obamacare" was first used by opponents, then reappropriated by supporters, and eventually used by President Obama himself. Together with the Health Care and Education Reconciliation Act of 2010 amendment, it represents the U.S. healthcare system's most significant regulatory overhaul and expansion of coverage since the passage of Medicare and Medicaid in 1965

The ACA's major provisions came into force in 2014. By 2016, the uninsured share of the population had roughly halved, with estimates ranging from 20 24 million additional people covered during 2016. The increased coverage was due, roughly equally, to an expansion of Medicaid eligibility and to major changes to individual insurance markets. Both involved new spending, funded through a combination of new taxes and cuts to Medicare provider rates and Medicare Advantage. Several Congressional Budget Office reports said that overall these provisions reduced the budget deficit, and that repealing the ACA would increase the deficit. The law also enacted a host of delivery system reforms intended to constrain healthcare costs and improve quality. After the law went into effect, increases in overall healthcare spending slowed, including premiums for employer-based insurance plans.

The act largely retains the existing structure of Medicare, Medicaid, and the employer market, but individual markets were radically overhauled around a three-legged scheme. Insurers in these markets are made to accept all applicants and charge the same rates regardless of pre-existing conditions or sex. To combat resultant adverse selection, the act mandates that individuals buy insurance and insurers cover a list of "essential health benefits". However, a repeal of the tax mandate, passed as part of the Tax Cuts and Jobs Act of 2017, will become effective in 2019. To help households between 100 400% of the Federal Poverty Line afford these compulsory policies, the law provides insurance premium subsidies. Other individual market changes include health marketplaces and risk adjustment programs

Affordable Care Act