(1) Companies may issue tariff supplements to reflect situations such as gas price fluctuations, city or county taxes, or county surcharges imposed under the provisions of RCW 36.58.045.

(2) Companies may not issue tariff supplements to make general rate increases.

(3) Supplements are subject to all applicable rules and procedures including transmittal letters, notice to customers and the commission, and proper tariff format. The commission will provide sample tariff supplement forms on request.

(4) Supplements to a tariff must be numbered consecutively. If a newly filed supplement cancels a previous supplement(s), that information must be clearly shown on the new supplement. For example: "Supplement 6 cancels Supplements 4 and 5."