Paid leave time, including vacation, sick, and administrative leave, used during the normal course of business and for which a member is paid shall be considered as service in determining a creditable year. This ruling does not include summer months between school terms when no service is rendered even though the member may be paid in 12 monthly payments or days in which the employer is closed for business and the days are not included in the employee's required number of work days. Certification of payment and copies of the employer's policy must be provided to TRS on request.