Miss. Code Ann. § 21-29-41: Miss. Code Ann. § 21-29-41

Upon retirement for nonduty disability as provided in Section 21-29-39 , a member shall receive for each year's active service one-fortieth ( 1 / 40 ) of the average monthly salary or compensation received by such member from the employer in the four-year or two-year period, as the case may be, next preceding the injury or illness causing such disability.