(1) The department, under RCW 18.106.320, may audit the employment records of the plumbing contractor or employer who verified the plumbing trainee hours.

(2) Every contractor must keep a record of trainee employment so the department may obtain the necessary information to verify plumbing trainee work experience.

(a) The contractor must keep the records of jobs performed for a least five years.

(b) Upon request, these records must be made available to the department for inspection within seven business days.

(3) The contractor must maintain time cards or similar records to verify:

(a) The number of hours the trainee worked as a supervised trainee by category.

(b) The type of plumbing work the trainee performed (e.g., commercial or residential).

(4) Any information obtained from the trainee's contractor or employer during the audit under the provisions of RCW 18.106.320 is confidential and is not open to public inspection under chapter 42.17 RCW.

(5) The department's audit may include, but will not be limited to, the following:

(a) An audit to determine whether the trainee and supervising plumber were employed by the same contractor or employer during the period for which the hours were submitted, the actual number of hours the trainee worked, and the category of plumbing work performed; and

(b) An audit covering a specific time period and examination of a contractor's or employer's books and records which may include their reporting of the trainee's payroll hours required for industrial insurance, employment security or prevailing wage purposes.