An exploration incentive credit for a mining operation may not exceed $20,000,000 and must be applied within 15 tax years or royalty payment periods after the taking of the credit is approved under AS 27.30.020(2), but the tax years or royalty payment periods in which the credit is applied need not be

1. (1) the tax year or royalty payment period in which the person first incurs liability for payment of tax or royalty based on the person's activity that is the basis of the claim of the exploration incentive credit; or
2. (2) consecutive periods.