Okla. Stat. tit. 21, § 12.1

Required service of minimum percentage of sentence - Effective date. A person committing a felony offense listed in Section 30 of this act on or after March 1, 2000, and convicted of the offense shall serve not less than eighty-five percent (85%) of the sentence of imprisonment imposed within the Department of Corrections. Such person shall not be eligible for parole consideration prior to serving eighty-five percent (85%) of the sentence imposed and such person shall not be eligible for earned credits or any other type of credits which have the effect of reducing the length of the sentence to less than eighty-five percent (85%) of the sentence imposed.