61 Pa. Code § 151.21
The following words and terms, when used in §§ 151.21-151.24, have the following meanings, unless the context clearly indicates otherwise:
Application-Use by the Department of a credit to pay a tax debit.
Assignment-The sale or exchange of a settled credit by a taxpayer (the assignor) to another taxpayer (the assignee) for application by the assignee to a tax debit in the assignee's account.
Conditional statutory credit-Those statutory credits which are subject to special conditions set forth by the statute establishing those credits. The credits may be utilized in the manner set forth in this chapter, subject to the special conditions or limitations set forth by the statute which creates them. An example is section 5 of the Neighborhood Assistance Tax Credit (62 P. S. § 2085).
Settled credit-A surplus which has been determined to be an overpayment upon settlement by the Department of the annual tax report to which it relates.
Tax debit-The term includes tax prinicipal, penalty and interest.
Transfer-The movement by the Department of a credit within the account of a taxpayer against a tax debit of the same taxpayer.
Unsettled credit-A surplus resulting from an apparent overpayment of a tax with respect to which a payment is made, either as a result of a tentative tax payment or of a regular payment, prior to settlement of the annual tax report to which it relates.
61 Pa. Code § 151.21