What is a 'pre-existing condition' and how does the ACA address it?

PRE-EXISTING CONDITION: A health condition (illness, injury) that EXISTED BEFORE the new health coverage began (e.g., diabetes, asthma, prior cancer). HISTORICAL PROBLEM: Before the ACA, insurers could DENY coverage, EXCLUDE the condition, or CHARGE MORE based on pre-existing conditions; ACA PROTECTION: Under the Affordable Care Act, health insurers generally CANNOT: deny coverage based on pre-existing conditions; charge higher premiums based on health status/pre-existing conditions; exclude coverage for pre-existing conditions (no pre-existing condition exclusion periods); GUARANTEED ISSUE: ACA-compliant plans must accept applicants regardless of health; COMMUNITY RATING: Premiums can vary only by age, location, tobacco use, and plan category — NOT health status; APPLIES to: ACA marketplace and most major medical plans; the ACA's pre-existing condition protections were a major reform; understanding what a pre-existing condition is and that the ACA prohibits denial/surcharge based on it (guaranteed issue, no health-based rating) is important health insurance exam content.