Okla. Stat. tit. 68, § 2357.304

A. Except as provided in subsection D of this section, for tax years 2009 through 2031, a qualified employee shall be allowed a credit against the tax imposed pursuant to Section 2355 of this title of up to Five Thousand Dollars ($5,000.00) per tax year for a period of time not to exceed five (5) years during the lifetime of the qualified employee. This credit may be claimed in nonconsecutive tax years. B. The credit authorized by this section shall not be used to reduce the tax liability of the taxpayer to less than zero (0). C. Any credit claimed, but not used, may be carried over, in order, to each of the five (5) subsequent taxable years. D. No credit otherwise authorized by the provisions of this section may be claimed for any event, transaction, investment, expenditure or other act occurring on or after July 1, 2010, for which the credit would otherwise be allowable. The provisions of this subsection shall cease to be operative on July 1, 2011. Beginning July 1, 2011, the credit authorized by this section may be claimed for any event, transaction, investment, expenditure or other act occurring on or after July 1, 2011, according to the provisions of this section.