Notwithstanding any other provision of law to the contrary, in any county in which assessment appeals boards have been created and are in existence, the time for equalization of assessments made outside the regular assessment period for those assessments, including assessments made pursuant to Sections 501, 503, 504, 531, and 531.5, shall be prescribed by rules adopted by the board of supervisors.
Ca. Rev. and Tax. Code § 1605