3.__Limitations.__A person entitled to a credit under this section for any taxable year may carry over and apply the portion of any unused credits to the tax liability on income derived from the production of biofuel for any one or more of the next succeeding 5 taxable years.__The credit allowed, including carryovers, may not reduce the tax otherwise due under this Part to less than zero.

4.__Certification.__A taxpayer engaged in the production of biofuels who is claiming a credit under subsection 2 shall provide information to the Commissioner of Environmental Protection regarding the biofuel being produced, including the quantity of biofuel products, the type of forest or agricultural product being utilized, the nature and composition of the biofuel being produced, the proportion and composition of any nonbiofuel with which the biofuel is blended and the type of application for which it is intended to be used.__Upon review of the information, the Commissioner of Environmental Protection shall provide the taxpayer with a letter of certification stating that the biofuel produced during the taxable year is eligible for a tax credit under this section and stating the number of gallons of biofuel produced during the taxable year.

5.__Application.__This section applies to tax years beginning on or after January 1, 2004.