Check your Pa Statutes. I found this:
Title 40, [section]991.2166 of Pennsylvania Statutes, entitled "Prompt Payment of Claims," provides that
(a) A licensed insurer or a managed care plan shall pay a clean claim submitted by a health care provider within forty-five (45) days of receipt of the clean claim. (2)
(b) If a licensed insurer or a managed care plan fails to remit the payment as provided under subsection (a), interest at ten per centum (10%) per annum shall be added to the amount owed on the clean claim.