Existing law, the Knox-Keene Health Care Service Plan Act of 1975, provides for the licensure and regulation of health care service plans by the Department of Managed Health Care and makes a willful violation of the act's requirements a crime. Existing law provides for the regulation of health insurers by the Department of Insurance. Existing law requires a health care service plan contract or disability insurance policy issued, amended, delivered, or renewed on or after January 1, 2000, that covers prescription benefits to include coverage for insulin if it is determined to be medically necessary. This bill would prohibit a large group health care service plan contract or health insurance policy issued, amended, delivered, or renewed on or after January 1, 2026, or an individual or small group health care service plan contract or health insurance policy on or after January 1, 2027, from imposing a copayment, coinsurance, deductible, or other cost sharing of more than $35 for a 30-day supply of an insulin prescription drug, except as specified. On and after January 1, 2026, the bill would prohibit a health care service plan or health insurer from imposing step therapy as a prerequisite to authorizing coverage of insulin, and, for a large group health care service plan contract or health insurance policy, would require at least one insulin for a given drug type in all forms and concentrations to be on the prescription drug formulary. The bill would limit the $35 cap for an individual or small group health care service plan contract or health insurance policy to only Tier 1 and Tier 2 insulin if the drug formulary is grouped into tiers, except as provided. Because a willful violation of these provisions by a health care service plan would be a crime, the bill would impose a state-mandated local program. The California Constitution requires the state to reimburse local agencies and school districts for certain costs mandated by the state. Statutory provisions establish procedures for making that reimbursement. This bill would provide that no reimbursement is required by this act for a specified reason.