Hawaii late fee law

10%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.

When there is no express written contract fixing a different rate, interest is allowed at 10% per year (HRS § 478-2), with an exception for obligations of the State (prime rate, not to exceed 10%). Verified via full statute text on FindLaw's Hawaii Revised Statutes, corroborated by Justia and capitol.hawaii.gov search results (the official capitol.hawaii.gov page returned 403 to direct fetch).

For any transaction OTHER than a consumer credit transaction, a home business loan, or a credit card agreement, it is lawful to stipulate by written contract for any rate of interest not otherwise prohibited by law (HRS § 478-4) - i.e., ordinary B2B/commercial written contracts have no usury cap. Consumer credit transactions and home business loans are capped at 1% per month / 12% per year. HRS § 478-8 separately exempts from usury, among others, credit sales of goods or services where the rate does not exceed 18% per year.

public+private-construction

Public: HRS § 103-10 - the State and counties must pay proper statements for goods/services within 30 calendar days; late amounts bear interest at the Wall Street Journal prime rate for the quarter plus 2%, from day 30 until payment (federal-funds contingency exception). Private construction: HRS § 444-25 - contractors must pay subcontractors within 10 days of the later of invoice or receipt of owner payment; unpaid amounts bear interest at 1.5% per month absent a bona fide dispute (expressly inapplicable to ch. 103 public contracts). No general private non-construction prompt-payment act was found.

No Hawaii statute specifically governing flat late fees on commercial invoices was found; agreed late fees are generally enforceable subject to the liquidated-damages/penalty doctrine. Interest-type charges in written B2B contracts are effectively uncapped under HRS § 478-4; absent a written rate, the 10% default of § 478-2 applies.