The Department of Taxation shall promulgate guidelines for the use of local governments in administering the taxes imposed under the authority of this chapter. In preparing such guidelines, the Department shall not be subject to the provisions of the Administrative Process Act (§ 2.2-4000 et seq.) for guidelines promulgated on or before July 1, 2001, but shall cooperate with and seek the counsel of local officials and interested groups and shall not promulgate such guidelines without first conducting a public hearing. Such guidelines shall be updated during the 1994 taxable year and available for distribution to local governments on July 1, 1995. Thereafter, the guidelines shall be updated triennially. After July 1, 2001, the guidelines shall be subject to the Administrative Process Act and accorded the weight of a regulation under § 58.1-205. The Tax Commissioner shall have the authority to issue advisory written opinions in specific cases to interpret the provisions of this chapter and the guidelines issued pursuant to this section; however, the Tax Commissioner shall not be required to interpret any local ordinance. The guidelines and opinions issued pursuant to this section shall not be applicable as an interpretation of any other tax law.