Va. Code Ann. § 53.1-198

Every person who, on or before June 30, 1981, was convicted of a felony and every person convicted of a misdemeanor, and to whom the provisions of §§ 53.1-151, 53.1-152 or § 53.1-153 apply, may choose the system of good conduct allowances established in §§ 53.1-199 through 53.1-202 to govern the computing of his discharge date and eligibility for parole. A person who chooses the system established in this article may not thereafter be governed by the laws establishing good conduct allowances in effect prior to July 1, 1981.