If a taxable entity is eligible for a credit that exceeds the limitation under § 171.658, the taxable entity may carry the unused credit forward for not more than 20 consecutive reports. Credits, including credit carryforwards, are considered to be used in the following order:
(1) a credit carryforward of unused credits accrued under Subchapter O before its repeal on January 1, 2008, and claimed as authorized by Section 18(d), Chapter 1 (H.B. 3), Acts of the 79th Legislature, 3rd Called Session, 2006;
(2) a credit carryforward under this subchapter; and
(3) a current year credit.