Utah 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.

Unless the parties to a lawful written, verbal, or implied contract expressly specify a different rate, the legal rate of interest for the contract - including a contract for services, a loan or forbearance of money, goods, or services, or a claim for breach of contract - is 10% per annum. Verified against the official Utah Legislature code PDF (as amended through 2019).

Utah Code § 15-1-1(1): parties to a lawful contract 'may agree upon any rate of interest' - there is no general usury cap on agreed rates for commercial/B2B credit. Consumer credit is separately regulated under the Utah Consumer Credit Code (Title 70C), which does not apply to commercial transactions.

public

Utah Prompt Payment Act (Utah Code §§ 15-6-1 to 15-6-5) covers state agency purchases: payment due per contract or within 60 days of invoice; overdue amounts accrue interest at 2% above the IRS refund-claim rate, adjusted quarterly (§ 15-6-2). A prime contractor paid by the agency must pay subcontractors/suppliers within 45 days (interest beginning day 31) at 15.5% per annum unless the subcontract says otherwise (§ 15-6-5). Does not apply to contracts disbursing federal funds. No general private-commercial prompt-payment act found.

No distinctive Utah statute on flat late fees for commercial invoices was found; the default rule applies - agreed late fees are enforceable if reasonable, subject to the liquidated-damages/penalty doctrine. Since Utah imposes no usury cap on agreed commercial rates (§ 15-1-1(1)), usury-recharacterization risk for B2B late charges is minimal.