What is a 'pre-existing condition'?

A pre-existing condition is a medical condition (diagnosed or known) that existed before health coverage took effect. Historically, individual health policies excluded pre-existing conditions from coverage, charged higher premiums for them, or denied coverage entirely. The Affordable Care Act (ACA) of 2010 prohibited pre-existing condition exclusions and discrimination in individual and small group health insurance starting in 2014 — insurers cannot deny coverage, charge higher premiums, or exclude benefits based on health history. Other policy types may still address pre-existing conditions: short-term health policies, some employer-based plans pre-ACA grandfathered exemptions, and Medicare Supplement plans in certain circumstances. Long-term care and disability income insurance can still consider pre-existing conditions during underwriting.