What does the characterization of the benefit as a nonrefundable income tax credit mean?

A nonrefundable credit can only be used to offset income tax liability. If the amount of the credit exceeds the taxpayer’s liability in the year earned, the unused portion of the credit may be carried forward and used against subsequent income tax liabilities for an additional 3 years. Because the credit offsets income tax only, the credit may only be claimed by an individual, corporation, and fiduciary income taxpayers, and the credit cannot be used to offset other taxes such as corporation franchise tax or sales tax.