N.D. Cent. Code § 40-46-27

In July of each year, the city employees' pension board may add, if found actuarially sound, a cost of living increase to the monthly amounts paid beneficiaries. The total monthly payment under this section shall not exceed sixty percent of the monthly salary average during the preceding thirty-six months for the same or comparable position in the city's employment service as held by the retiree in the last month of the retiree's employment.