North Dakota late fee law

6%per year

Attaches to the debt by operation of law when you agreed no rate, so it accrues before any lawsuit and can be stated on a demand letter.

Verified from the official Century Code text: '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.' The same section provides that, unless otherwise agreed in writing, all contracts bear the same rate of interest after maturity as before maturity.

Written contracts may fix a higher rate, subject to the § 47-14-09 usury ceiling: no more than 5.5 percentage points above the current cost of money as reflected by the average rate on six-month U.S. Treasury bills for the preceding six months (computed and declared monthly by the state banking commissioner), with a floor - the maximum allowable ceiling may not be less than 7%. Critically for B2B (verified text): the ceiling does NOT apply to loans made to corporations, LLCs, cooperative corporations/associations, or trusts; partnerships/limited partnerships filing partnership returns; any loan or forbearance whose principal exceeds $35,000; loans by regulated/federally- or state-supervised lending institutions; or bona fide pawn transactions ≤ $10,000 - so most commercial credit is uncapped by contract. Usury forfeits all interest plus 25% of principal (§ 47-14-10) and is a class B misdemeanor (§ 47-14-11).

public

N.D.C.C. ch. 13-01.1: every state agency, political subdivision, or school district acquiring property or services must pay by the contract date or, if none, within 45 days after receipt of the invoice; overdue amounts accrue interest at 1.75% per month unless the contract specifies a different rate. This applies only to public entities - no prompt-payment statute for private commercial or private construction invoices was found.

Distinctive verified rule for loans: § 47-14-05 provides that '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.' Also, § 47-14-09 forbids contracting for interest on overdue interest (with a narrow exception). Ordinary trade-invoice late fees default to contract/liquidated-damages principles.