N.D. Cent. Code § 65-04-20

An employer, subject to section 65-04-22, may pay the annual premium in installments. Interest must be charged at the prevailing base rate posted by the Bank of North Dakota plus two and one-half percent. The interest charged must be at least six percent per annum. Interest must be charged on all premiums deferred under this section. Upon default in payment of any installment, the penalties apply which are provided in sections 65-04-22 and 65-04-33.