An employment certificate must be in writing and must be issued by the minor’s parent or guardian. The parent or guardian who certifies, or rejects, the employment certificate must file a completed copy with the department of labor and human rights, the employer, the principal of    the school which the minor attends, or a principal in the municipality in which the minor resides, within ten days of certification or rejection. No employment certificate is required for any minor then in, or who is about to enter, the minor’s own employment or the employment of a firm, corporation, or limited liability company of which the minor is a member, officer, or manager. The labor commissioner shall make the certificates of employment available.