Alaska late fee law

10.5%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.

"The rate of interest in the state is 10.5 percent a year and no more on money after it is due" absent an express written contract rate - i.e., overdue obligations, including unpaid invoices with no agreed rate, bear 10.5% per annum. Statute text verified via FindLaw's reproduction of AS 45.45.010 (official akleg.gov page could not be fetched), corroborated by public-contract statutes that cross-reference the § 45.45.010(a) rate.

Parties may contract in writing for a higher rate, but under AS 45.45.010(b) the agreed rate generally may not exceed the greater of 10% or five percentage points above the Federal Reserve 12th District discount rate on the day the contract is made. Key B2B carve-out: contracts and loan commitments where the principal amount exceeds $25,000 are exempt from the usury limitation entirely, so most commercial credit arrangements above that threshold may bear any agreed rate.

public

Public construction/works contracts only: payment to the prime is due within 30 days (21 days where grant or federal money is used), and primes must pay subcontractors within 8 working days of receiving payment; late payments and wrongfully withheld retainage accrue interest at the AS 45.45.010(a) rate (10.5% per annum). No general private-commercial prompt-payment act was found.

No distinctive Alaska rule on flat commercial late fees was found; default liquidated-damages/penalty analysis applies. Note the usury trap for smaller balances: an agreed late-payment interest rate above the § 45.45.010(b) ceiling can be usurious where the principal is $25,000 or less; above $25,000 the cap does not apply.