N.D. Cent. Code § 61-16.1-35
Improvement warrants may be used in making payments on contracts for construction of the project for which the special assessment fund was created, or may be sold for cash at not less than ninety-eight percent of par and accrued interest, and the proceeds thereof, less accrued interest, shall be credited to the construction account of such fund and shall be used exclusively to pay such contracts and construction costs. Any balance remaining in any construction account after completion of a project shall be transferred to the sinking fund account of the assessment fund. The treasurer of the district shall pay special assessment warrants and any interest coupons attached thereto as they mature and are presented for payment out of the fund on which they are drawn and shall cancel the warrants and any coupons when paid.
N.D.C.C. § 61-16.1-35