California Code, Insurance Code - INS § 10123.2045

(a) A health insurance policy issued, amended, or renewed on or after January 1, 2026, that provides prescription drug coverage shall not calculate an insured's cost sharing at an amount that exceeds the actual rate paid by the insurer for the prescription drug.  Cost sharing shall include deductibles and coinsurance.

(b) To the extent that a health insurance policy with a pharmacy benefit manager issued, amended, or renewed on or after January 1, 2026, includes disclosure of the net price paid by the pharmacy benefit manager or group purchasing organization, then an insured's cost sharing shall not be calculated at an amount that exceeds that net price paid.