1. Any amount of tax credit which exceeds the tax due or which is applied for and otherwise eligible for issuance but not issued shall not be refunded but may be carried over to any subsequent taxable year, not to exceed a total of five years for which a tax credit may be taken for each child adopted.

2. Tax credits that are assigned, transferred or sold as allowed in section 135.327 may be assigned, transferred or sold in their entirety notwithstanding the taxpayer’s tax due.