N.D. Cent. Code § 15-39.1-10.2

Every person receiving monthly benefits from the fund on an account on which benefits were being paid on June 30, 1985, shall receive an increase in benefits beginning July 1, 1985, equal to one percent for each year the person has been retired under the fund. No member may receive more than a ten percent or more than a forty dollar per month increase in benefits under this section.