As used in this part:

1. (1) "Gross tax liability" means a taxpayer's total income tax liability before the application of any state tax credits and prior to claiming any estimated income tax payments or individual income tax withholding payments, as shown on the tax return of the taxpayer for any year; and

2. (2) "Net tax liability" means a taxpayer's income tax due the state:

   1. (A) After crediting all tax credits claimed by the taxpayer; and
   2. (B) Before the application of estimated income tax payments or individual income tax withholding payments.