Sixteen Years of the Affordable Care Act

The Patient Protection and Affordable Care Act (ACA) was passed on this day 16 years ago, enacting some of the most wide-ranging health care reforms in modern American history and bolstering coverage and protections for Medicare and Medicaid beneficiaries. Over its four-year rollout, the law instituted new consumer protections, closed gaps in coverage, expanded access for middle- and low-income consumers, and established the Health Insurance Marketplace. These changes contributed to a historic decline in the number of uninsured Americans, which fell from 45.2 million in 2013 to 26.4 million in 2022. In 2025, over 23 million people were enrolled in ACA coverage.

Components of the ACA

Patient Protections

Prior to the passage of the ACA, many of the most at-risk populations were systemically denied or priced out of care. The law sought to remedy this by instituting patient protections prohibiting discriminatory limits on coverage.

The ACA prevents most insurers from denying coverage based on age or pre-existing conditions, protecting coverage and affordable care for older people, people with disabilities, and others with chronic or complex medical conditions. It also eliminated lifetime and annual limits on coverage, so that people could count on remaining covered through expensive or extended treatment.

Expanding Access to Care

The ACA made health care more accessible to Americans by offering a Marketplace of health insurance supported by federal financial assistance—for those who are not eligible for public programs or enrolled in employer-sponsored coverage—and by expanding Medicaid eligibility.

By requiring all Marketplace plans to offer a baseline of essential health benefits, the ACA made comprehensive health care—including mental health services and prescription drug coverage—more widely available. Under this requirement, ACA-compliant plans also generally cover preventive care services at no cost to the beneficiary.

The Medicaid expansion program gave states the option to extend Medicaid eligibility for low-income, non-elderly adults (ages 19–64) without dependent children. This has allowed states to eliminate coverage gaps for individuals previously not eligible for Medicaid and receive federal funding to better meet their populations’ needs. To date, 41 states (including D.C.) have expanded Medicaid.

Changes to Medicare

The ACA ushered in key changes to Medicare to improve coverage and financial sustainability. Its restructuring of Part D closed the “donut hole” that had increased beneficiary cost sharing on prescription drugs, paving the way for further drug coverage expansions through the Inflation Reduction Act. It also aimed to curb the growing issue of Medicare Advantage overpayment, which balloons costs and undermines the solvency of Medicare.

Challenges Facing the ACA

The ACA has faced many challenges in Congress and the courts. Several Supreme Court decisions have altered aspects of the law and its implementation, but its key provisions have been upheld time and time again.

Most recently, HR 1, the 2025 budget bill, included threats to the ACA whose impacts are already beginning to be seen. Congress allowed the expiration of the enhanced premium tax credits that were passed in 2021 to make ACA Marketplace plans more affordable, leading to dramatic price increases for most enrollees. HR 1 also instituted various bureaucratic barriers to keeping Marketplace coverage and cut away at states’ abilities to administer and maintain health programs under Medicaid expansion.

At Medicare Rights, we believe affordable and accessible health care should be a goal embraced by all. We are committed to working to expand access to health care for current and future Medicare beneficiaries.