(a). Unless an employer has elected to front-load sick leave under 8 AAC 15.108, an employer shall establish a consecutive 52 week period for purposes of calculating an employee's annual accrual of sick leave. If an employer does not specify an accrual year under this section, an employee shall accrue sick leave on a calendar year basis. Except as provided in 8 AAC 15.108, an employee is entitled to carry over unused sick leave to the next accrual year.