Va. Code § 53.1-199
Every person who, on or after July 1, 1981, has been 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, and every person who, in accordance with § 53.1-198, chooses the system of good conduct allowances set out herein, may be entitled to good conduct allowance not to exceed the amount set forth in § 53.1-201. Such good conduct allowance shall be applied to reduce the person's maximum term of confinement while he is confined in any state correctional facility. One-half of the credit allowed under the provisions of § 53.1-201 shall be applied to reduce the period of time a person shall serve before being eligible for parole.
Any person who, on or after July 1, 1993, has been sentenced upon a conviction of murder in the first degree, rape in violation of § 18.2-61, forcible sodomy, animate or inanimate object sexual penetration or aggravated sexual battery and any person who has been sentenced to a term of life imprisonment or two or more life sentences shall be classified within the system established by § 53.1-201. Such person shall be eligible for no more than ten days good conduct credit for each thirty days served, regardless of the class to which he is assigned. One-half of such credit shall be applied to reduce the period of time he shall serve before being eligible for parole. Additional good conduct credits may be approved by the Director for such persons in accordance with § 53.1-191.
Va. Code § 53.1-199