Requires group health plans and health insurers to cover diagnostic and supplemental breast exams without any cost-sharing (no deductibles, copays, or coinsurance). Plans may still use prior authorization and other utilization controls, stronger State laws remain in force, and grandfathered plans must comply. A safe harbor protects high-deductible health plans (HDHPs) from losing Health Savings Account (HSA) eligibility if they waive the deductible for these exams. The rule applies to plan years beginning on or after 2026-01-01.