N.D. Cent. Code § 20.1-13-21
With an application for a motorboat number and license under section 20.1-13-03 by an applicant in whose name the motorboat has not previously been licensed, the applicant shall present proof of payment of sales or use tax that was due upon acquisition or bringing the motorboat into this state for storage or use in this state or shall present proof of exemption from sales or use taxes. Credit for taxes paid by the applicant upon acquisition of the motorboat in another state must be allowed as provided in section 57-40.2-11 if proof of that payment is presented. To establish that the motorboat was acquired through a casual sale and qualifies for exempt status, the applicant shall present a receipt for the sale signed by the seller and showing the seller's name and address. The department may waive the furnishing of a signed receipt for a casual sale if the applicant shows good cause why a receipt is unavailable and signs a statement showing the name and address of the seller and stating that to the best of the applicant's knowledge the seller is not in the business of selling boats.
N.D.C.C. § 20.1-13-21