TX SB959

Prohibits health benefit plan issuers from modifying an enrollee's contracted benefit level for prescription drugs that were approved or covered in the prior plan year, if the enrollee was continuously covered, the drug was prescribed for a medical condition or mental illness, and the prescriber determines it is the most appropriate treatment

Expands the list of drug coverage modifications requiring 60-day advance written notice to include increasing coinsurance, copayments, deductibles, or other out-of-pocket expenses, and reducing maximum drug coverage amounts

Exempts self-funded health benefit plans under ERISA from these prescription drug modification requirements, in addition to existing exemptions for Medicare supplemental policies, workers' compensation, Medicaid, and limited-benefit plans

Allows modifications favorable to enrollees (adding drugs to formulary, reducing out-of-pocket costs, removing utilization review requirements) to be made at any time without notice

Permits insurers to remove drugs from formularies or deny coverage if the FDA raises clinical safety concerns, the manufacturer discontinues the drug, or the drug is removed from the market; also preserves pharmacists' ability to substitute FDA-approved interchangeable biologics or generic equivalents

Applies to health benefit plans delivered, issued, or renewed on or after January 1, 2026, with an effective date of September 1, 2025