Mass. Gen. Laws ch. 18 § 5H
Notwithstanding any other provision of general or special law, rule or regulation, the department shall be subrogated to the right of any recipient of medical assistance provided pursuant to chapter one hundred and eighteen E to proceed against any health care insurer that is or may be liable to pay for covered services obtained by a recipient of medical assistance to the extent of any medical benefits provided by the department on behalf of the recipient or his dependents.
A recipient of medical assistance or any person legally obligated to support and having actual or legal custody of a recipient of medical assistance shall inform the department of any health insurance available to such recipient upon initial application and redetermination for eligibility for assistance and shall make known the nature and extent of any health insurance coverage to any person or institution that provides medical benefits to the recipient or his dependent.
No policy for health insurance for health care delivery administered, issued or renewed in the commonwealth shall contain any provision denying or reducing benefits to a person who is eligible for or who is receiving medical assistance under said chapter one hundred and eighteen E.
A provider of medical assistance under said chapter one hundred and eighteen E shall determine whether any recipient for whom it provides medical benefits that are or may be eligible for reimbursement pursuant to said chapter one hundred and eighteen E is a subscriber or beneficiary of a health insurance plan. The department is the payor of last resort, and accordingly a provider shall request payment for medical benefits it provides from a health insurer which is or may be liable for the medical benefits so provided, before payment is requested from the department.
Payment by the department under the medical assistance program shall constitute payment in full; subsequent to any such payment a provider may not recover from any health insurer an amount greater than the amount so paid by the department for any service for which the department is to be the payor of last resort.
Notwithstanding any provision of law, all health insurers doing business in the commonwealth shall provide information to the department to the extent sufficient to identify persons who are recipients of assistance under said chapter one hundred and eighteen E and who are also beneficiaries under any policy for health insurance in force and effect in the commonwealth.
Mass. Gen. Laws ch. 18, § 5H