(1) The term "employment" shall not include services performed by a musician or entertainer under a written contract with a purchaser of the services for a specific engagement or engagements when such musician or entertainer performs no other duties for the purchaser and is not regularly and continuously employed by the purchaser. The contract shall designate the leader of the music or entertainment group. A music or entertainment business or a leader of a music or entertainment group shall be considered an employer and not a purchaser of music or entertainment services.
(2) Any musician or entertainer who performs for a music or entertainment business or as a member of a music or entertainment group is deemed an employee of the business or group and the business or the leader of the group shall be required to register as an employer with the department.
(3) Purchasers of services under subsection (1) of this section shall not be subject to RCW
50.24.130 relating to a principal's liability for unpaid contributions if the services are purchased from a business or group registered as an employer with the department.
(4) The term "music or entertainment business" or "group" as used in this section means an employer whose principal business activity is music or entertainment. The term does not include those entities who provide music or entertainment for members or patrons incidental to their principal business activity, and does not include an individual employing musicians or entertainers on a casual basis.