California Code, Revenue and Taxation Code - RTC § 40046

The amount of kilowatt-hours of electrical energy determined by or stated on a billing of an electric utility in accordance with its business practices and accounting records to have been sold to a consumer during any calendar quarter or billing period of the electric utility shall be presumed to be correct.  The presumption may be rebutted by evidence which establishes that the amount of kilowatt-hours was other than such amount.