Interest on unpaid invoices in North Dakota: 6% a year if no rate was agreed; the most you can set depends on the deal

North Dakota's rate when no rate was agreed

6% a year. 6% a year applies to any legal indebtedness unless a different (lawful) rate is contracted for in writing.

• “Interest for any legal indebtedness must be at the rate of six percent per annum unless a different rate not to exceed the rate specified in section 47-14-09 is contracted for in writing.” — N.D.C.C. § 47-14-05, read November 6, 2026

The most you can set in North Dakota

For a homeowner: 6-month U.S. Treasury bill average + 5.5% (floor 7%). N.D.C.C. 47-14-09 caps interest on a 'loan or forbearance of money, goods, or things in action'. The Commissioner declares the figure monthly. It depends: see N.D.C.C. 47-14-09.

For a business customer: It depends: see N.D.C.C. § 47-14-09(2). The cap does not apply to loans made to corporations, LLCs, cooperatives, trusts, or partnerships/associations filing a partnership return, nor to any loan or forbearance over $35,000.

How the most you can set moves: Usury cap = average 6-month T-bill + 5.5%, floor 7%, declared monthly by the ND Commissioner.

• “any greater sum or greater value for the loan or forbearance of money, goods, or things in action than five and one-half percent per annum higher than the current cost of money as reflected by the average rate of interest payable on United States treasury bills maturing in six months in effect for North Dakota for the six months immediately preceding the month in which the transaction occurs, as computed and declared on the last day of each month by the state banking commissioner, but that in any event the maximum allowable interest rate ceiling may not be less than seven percent” — N.D.C.C. § 47-14-09(1), read November 6, 2026
• “The usury rate is the maximum rate of interest which may be charged for loans of money by non-regulated lenders.” — N.D. Dept. of Financial Institutions, Usury Rate (N.D.C.C. § 47-14-09), read November 6, 2026
• “b. Loan made to a foreign or domestic corporation, foreign or domestic limited liability company, cooperative corporation or association, or trust; c. Loan made to a partnership, limited partnership, or association that files a state or federal partnership income tax return; d. Loan or forbearance of money, goods, or things in action the principal amount of which amounts to more than thirty-five thousand dollars” — N.D.C.C. § 47-14-09(2), read November 6, 2026

Late fees in North Dakota

See the state's words below. Rules seen cover loans (late payment penalty must be agreed in signed loan documents) and retail installment sales of personal property (goods), not service invoices.

• “A charge for a late payment penalty may be imposed only if the amount of the late charge or the method of calculation of the late charge has been agreed to by the parties in the loan documents that are signed by the borrower.” — N.D.C.C. § 47-14-05, read November 6, 2026
• “A contract may provide for the payment by the buyer of a delinquency and collection charge on each installment in default for a period of more than ten days in an amount equal to ten percent of the delinquent installment payment or ten dollars, whichever is less” — N.D.C.C. § 51-13-02(2)(e), read November 6, 2026
• “"Retail installment sale" or "sale" means a sale, other than for the purpose of resale, of personal property by a retail seller to a retail buyer for a price payable in one or more deferred payments.” — N.D.C.C. § 51-13-01(11), read November 6, 2026

Does North Dakota want it agreed in advance?

Agreed in advance: yes, in the cases below. A rate above 6% must be 'contracted for in writing'; a late payment penalty must be agreed in loan documents signed by the borrower (the text speaks of loans).

• “Interest for any legal indebtedness must be at the rate of six percent per annum unless a different rate not to exceed the rate specified in section 47-14-09 is contracted for in writing.” — N.D.C.C. § 47-14-05, read November 6, 2026
• “A charge for a late payment penalty may be imposed only if the amount of the late charge or the method of calculation of the late charge has been agreed to by the parties in the loan documents that are signed by the borrower.” — N.D.C.C. § 47-14-05, read November 6, 2026

Homeowners and businesses in North Dakota

North Dakota's own words on it are below.

• “b. Loan made to a foreign or domestic corporation, foreign or domestic limited liability company, cooperative corporation or association, or trust; c. Loan made to a partnership, limited partnership, or association that files a state or federal partnership income tax return; d. Loan or forbearance of money, goods, or things in action the principal amount of which amounts to more than thirty-five thousand dollars” — N.D.C.C. § 47-14-09(2), read November 6, 2026

Prompt payment on private construction in North Dakota

Not found in our check for North Dakota.

• “Every state agency, political subdivision, or school district, which acquires property or services pursuant to a contract with a business shall pay for each complete delivered item of property or service on the date required by contract” — N.D.C.C. § 13-01.1-01, read November 6, 2026
• “Interest must accrue and be made on payments overdue under section 13-01.1-01 at the rate of one and three-fourths percent per month, unless a different rate is specified within the contract upon which the claim is based.” — N.D.C.C. § 13-01.1-02, read November 6, 2026

Work out a late charge in North Dakota

Starts at North Dakota's 6%, the rate when none was agreed, not a maximum.

What was not checked for North Dakota

• North Dakota's text does not say plainly whether its usury cap (47-14-09) reaches a past-due service invoice or only loans.

Check North Dakota's own text

Before you charge: read N.D.C.C. § 47-14-05 and the other North Dakota texts quoted on this page, or ask a lawyer. As of November 6, 2026.

This is a plain-words summary of each state's own laws as of November 6, 2026, not legal advice. Rules have exceptions. Check the state's own text, linked on every state's page, or a lawyer before you charge a late fee or interest.

Compare North Dakota with every state's answer, or with its neighbours just below.

Next door to North Dakota

• Minnesota: 6% if none agreed, depends by agreement
• Montana: 10% if none agreed, depends by agreement
• South Dakota: 15% if none agreed, depends by agreement

Official sources for North Dakota

• N.D.C.C. § 47-14-05 — read November 6, 2026
• N.D. Dept. of Financial Institutions, Usury Rate (N.D.C.C. § 47-14-09) — read November 6, 2026
• N.D.C.C. § 51-13-02(2)(e) — read November 6, 2026
• N.D.C.C. § 13-01.1-01 — read November 6, 2026

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