Wash. Rev. Code § 82.16.090

(1) Any customer billing issued by a light or power business or gas distribution business that serves a total of more than twenty thousand customers and operates within the state shall include the following information:

(a) The rates and amounts of taxes paid directly by the customer upon products or services rendered by the light and power business or gas distribution business;

(b) The rate, origin and approximate amount of each tax levied upon the revenue of the light and power business or gas distribution business and added as a component of the amount charged to the customer. Taxes based upon revenue of the light and power business or gas distribution business to be listed on the customer billing need not include taxes levied by the federal government or taxes levied under chapters 54.28, 80.24, or 82.04 RCW; and

(c) The total amount of kilowatt-hours of electricity consumed for the most recent twelve-month period or other information that provides the customer with information regarding their energy usage over a twelve-month period.

(2) A light or power business or gas distribution business that serves a total of more than twenty thousand customers and operates within the state may include information regarding rates over the most recent twelve-month period on any customer billing.

Effective date—1988 c 228: "This act shall take effect on January 1, 1989." [ 1988 c 228 s 2.]