"Agency." A Commonwealth agency, office, department, authority, board or commission of the executive branch or a political subdivision receiving federal tax information, even though the federal tax information may be forwarded to the agency from or through any of the following:
"Contractor." An individual who is not an employe of an agency and performs work functions for an agency under the terms of a written agreement, regardless of whether the written agreement is directly with the agency or a third party.
"Federal tax information." Includes any "return" or "return information" as defined in section 6103 of the Internal Revenue Code of 1986.
71 P.S. § 86