The ACA introduced consumer protections, most notably prohibiting insurers from denying coverage or charging more due to pre-existing conditions.

One of the most widely popular and impactful provisions of the ACA was the elimination of medical underwriting based on health status. Prior to the ACA, health insurance companies could, and often did, deny coverage, charge higher premiums, or exclude certain benefits for individuals with pre-existing conditions like diabetes, cancer, or heart disease. This left millions vulnerable and unable to secure affordable, comprehensive coverage. The ACA mandated that insurers offer coverage to all applicants regardless of health status (known as 'guaranteed issue') and could not charge higher premiums based on health (known as 'community rating' for health, age, and tobacco use, with limits). This provision fundamentally reshaped the individual health insurance market, providing critical security for those with ongoing health needs and shifting the risk pool to be more inclusive.