In Westinghouse Electric Corp. v. Workers' Compensation Appeal Board (Weaver), 823 A.2d 209 (Pa. Cmwlth. 2003), the Court held that when medical expenses incurred for treatment of any injury are initially paid by a health insurer and the injury is subsequently determined to be compensable, the employer is obligated to pay the provider any difference between the re-priced amount to which it is entitled under the Act and the amount it actually received. In Westinghouse, Mary Ann Weaver (Weaver) had sustained a work related injury. Her bills were initially paid by her private health insurer, Highmark Blue Cross/Blue Shield (Highmark). The amount paid by Highmark to each provider was less than the repriced amount under the Act. After a hearing on Weaver's claim petition, the WCJ found, based on the stipulations of the parties, that Weaver sustained a work related injury and incurred certain medical bills for reasonable and necessary treatment. The WCJ ordered that the medical expenses were to be repriced in accordance with the medical costs containment regulations and directed Westinghouse to reimburse Highmark 80% of the repriced expenses and to pay Weaver's providers the difference due between the repriced amount and the amount received by the providers from Highmark. Westinghouse appealed and argued, inter alia, that the WCJ erred in assessing penalties and interest based upon the difference due between the repriced amount and Highmark's payment. Westinghouse argued that its obligations under the Act were satisfied by its reimbursement to Highmark for its payment to the providers. The Court disagreed with Westinghouse and held: Employer's Westinghouse obligation under the Act is to pay, in a timely manner, Claimant's Weaver medical bills and expenses and this includes any difference between the repriced amount and any lesser amount paid by an insurer if such payment results in the provider being underpaid. Accordingly, Employer Westinghouse is responsible for the difference owed to the providers...Westinghouse, 823 A.2d at 216.