N.D. Cent. Code § 39-04-23: Registered motor vehicle transporting property may change registration to higher or lower registered gross weight

Any owner of a motor vehicle transporting property who has licensed the vehicle for any gross weight limitations may change the registration to a higher registered gross weight limitation by the payment of the difference between the fee required for the new registration and the fee paid for the registration under which the vehicle is being operated. The fee must equal one-twelfth of the annual higher registration fee less one-twelfth of the registration fee already paid, the difference multiplied by the number of whole and partial calendar months remaining in the registration period. In no event may the fee be less than five dollars.