(1) The parent or parents of a person at least eighteen years of age but under twenty-one years of age may elect to exclude from mandatory coverage under this title the parent's employment of that person in agricultural activities on their family farm if:

(a) The person resides with his or her parent or parents or resides on their family farm; and

(b) The parent or parents file a written notice with the department electing exclusion from coverage.

(2) A parent or parents who have elected to exclude a person under this subsection may subsequently obtain coverage for that person under RCW 51.12.110.