Wash. Admin. Code § 458-20-205
When building companies, apartment house owners or other real estate owners or lessors furnish utility services such as heat and electrical energy to their own tenants of office buildings, apartment houses and storerooms under circumstances indicating it is a part of the normal and customary landlord-tenant relationship and the charge made therefor is the cost of this utility service to the owner or lessor prorated among his tenants based upon the use or consumption of such services, the income derived therefrom is construed to be incidental to and a part of gross income from the renting or leasing of real estate and not subject to the provisions of the business and occupation tax. This is true whether the charge therefor is included in a lump sum rental or is billed separately. However, when the furnishing of utility services is not in accordance with the foregoing, the income derived therefrom is considered to be a separate business activity and is taxable under the appropriate chapter of the Revenue Act.
Revised June 1, 1970.
Wash. Admin. Code § 458-20-205
Order ET 70-3, § 458-20-205 (Rule 205), filed 5/29/70, effective 7/1/70.