There are several ways that a beneficiary can challenge a health care plan's denial of coverage for gender-affirming care. First, denials might run afoul of federal and state civil rights laws prohibiting workplace discrimination on the basis of sex. Second, ambiguous or vague denial criteria might be challenged under ERISA, where applicable. This article will focus mainly on a third law: Section 1557 of the Affordable Care Act (ACA), which prohibits health insurance plans from discriminating against beneficiaries on the bases of race, sex, age and disability.