As used herein:

The terms "real estate broker" and "real estate salesman" mean, respectively, a person licensed as such under the provisions of chapter 18.85 RCW.

A real estate broker is engaged in business as an independent contractor and is taxable under the service and other activities classification upon the gross income of the business.

The measure of the tax on real estate commissions earned by the real estate broker shall be the gross commission earned by the particular real estate brokerage office including that portion of the commission paid to salesmen or associate brokers in the same office on a particular transaction: Provided, however, That where a real estate commission is divided between an originating brokerage office and a cooperating brokerage office on a particular transaction, each brokerage office shall pay the tax only upon their respective shares of said commission; and provided further, that where the brokerage office has paid the tax as provided herein, salesmen or associated brokers within the same brokerage office shall not be required to pay a similar tax upon the same transaction. RCW 82.04.255.

Thus, with the exception of cooperating brokerage offices, no deduction is allowed for commissions, fees or salaries paid by a broker to another broker or salesman, nor for other expenses of doing business.

The term "gross income of the business" includes gross income from commissions, fees and other emoluments however designated which the agent receives or becomes entitled to receive, but does not include amounts held in trust for others. (See also WAC 458-20-111, advances and reimbursements.) No deductions are allowed for dues, charges, and fees paid to multiple listing associations.

Real estate salesmen are presumed to be independent contractors. They are subject to the service and other activities classification of the business and occupation tax on gross income from real estate commissions and fees earned where the brokerage office at which the real estate salesman's license is posted has not paid the tax on the gross commission.