N.D. Cent. Code § 40-22-37
If the contractor to whom a contract is let properly performs the work therein designated, the governing body, at least once in each calendar month during the continuance of such contract work, shall meet, receive, and consider estimates furnished by the agent, engineer, or architect acting for the municipality or if not so furnished, then by the contractor, and shall allow such estimates in an amount of the estimated value of the labor and material furnished upon such contract, and of the material then upon the ground for use in such contract, subject to retentions equal to ten percent of each estimate presented until such time as the project is fifty percent completed, with no further retainage on estimates during the continuance of the contract. The governing body may, however, upon completion of ninety-five percent of the contract according to the estimates, pay to the contractor ninety-five percent of the amount retained from previous estimates. Any amount retained after ninety-five percent completion of the contract shall be paid to the contractor in such amounts and at such times as are approved by the municipality, upon estimates by its agent, engineer, or architect or the contractor, with final payment of all moneys due to the contractor to be made immediately following completion and acceptance of the project. The governing body, immediately after considering and allowing any such estimate, shall certify and forward the same to the city auditor or other official having the power to draw warrants, who forthwith shall draw a warrant upon the proper fund and transmit the same promptly to the contractor entitled thereto. In case the governing body shall fail or neglect to receive and allow such estimate or certify any estimate or final payment upon completion and acceptance or the proper officer required to issue such warrant shall fail or neglect to issue a warrant as provided herein, for a period of more than thirty days from the date of such estimate or completion date, then said estimate or final payment, together with any retainage properly payable, shall draw interest from its date at the rate per annum of two percentage points below the Bank of North Dakota prime interest rate as set thirty days from the date of such estimate or completion date until the issuance of a proper warrant therefor. Such interest shall be computed and added to the face of said estimate, final payment, or retainage by the officer required to issue such warrant, shall be included in the warrant when drawn, and shall be charged to the fund from which payment for the improvement is to be made. On the amounts of estimates retained, as provided herein, the governing board, authorized committee, or public body in charge of such work may invest or deposit the retained amounts in any financial association or institution in North Dakota earning interest or dividends for the benefit of the contractor. Any amounts so invested or deposited shall remain in the name of the governing board, authorized committee, or public body in charge of such work until final payment of all money due to the contractor is to be made. Further, no contractor shall use such account in any manner whatsoever until released and received by the contractor upon completion of the contract.
N.D.C.C. § 40-22-37