Interest on unpaid invoices in Oklahoma: 6% a year if no rate was agreed; the most you can set depends on the deal

Oklahoma's rate when no rate was agreed

6% a year. 6% a year when there is no contract as to the rate.

• “The legal rate of interest shall be six percent (6%) in the absence of any contract as to the rate of interest, and by contract parties may agree to any rate as may be authorized by law, now in effect or hereinafter enacted.” — Okla. Stat. tit. 15, § 266, read November 6, 2026

The most you can set in Oklahoma

For a homeowner: Consumer credit sale: the greater of 30%/21%/15% tiered by balance, or 21% a year. Applies to a 'consumer credit sale' — goods or services bought by an individual primarily for personal, family or household use from a seller who regularly extends credit of that kind, where the debt is in installments or a credit service charge is made.

For a business customer: No cap by agreement for a sale other than a consumer credit sale. 14A § 2-605: for a sale other than a consumer credit sale (e.g. to an organization or for business purposes), the parties may contract for any credit service charge.

• “The credit service charge, calculated according to the actuarial method, may not exceed the equivalent of the greater of either of the following: (a) the total of (i) thirty percent (30%) per year on that part of the unpaid balances of the amount financed which is Three Hundred Dollars ($300.00) or less; (ii) twenty-one percent (21%) per year on that part of the unpaid balances of the amount financed which is more than Three Hundred Dollars ($300.00) but does not exceed One Thousand Dollars ($1,000.00); and (iii) fifteen percent (15%) per year on that part of the unpaid balances of the amount financed which is more than One Thousand Dollars ($1,000.00); or (b) twenty-one percent (21%) per year on the unpaid balances of the amount financed.” — Okla. Stat. tit. 14A, § 2-201(2), read November 6, 2026
• “"consumer credit sale" is a sale of goods, services or an interest in land in which (a) credit is granted by a person who regularly engages as a seller in credit transactions of the same kind; (b) the buyer is a person other than an organization; (c) the goods, services or interest in land are purchased primarily for a personal, family or household purpose; (d) either the debt is payable in installments or a credit service charge is made;” — Okla. Stat. tit. 14A, § 2-104(1), read November 6, 2026
• “2-201(2)(a)(i) $1,980.00 $2,040.00 2-201(2)(a)(ii) $1,980.01 - $6,600.00 $2,040.0 - $6,800.00 2-201(2)(a)(iii) $6,600.01 $6,800.01” — Okla. Dept. of Consumer Credit, Changes in Dollar Amounts – July 1, 2026 (Okla. Stat. tit. 14A, § 1-106), read November 6, 2026
• “With respect to a sale other than a consumer credit sale, the parties may contract for the payment by the buyer of any credit service charge.” — Okla. Stat. tit. 14A, § 2-605, read November 6, 2026

Late fees in Oklahoma

What the text says: Consumer credit sales: after 10 days late, up to the greater of 5% of the unpaid installment or the adjusted dollar amount ($34 from July 1, 2026; $5 in the statute's text); once per installment. Consumer credit sales of goods or services (incl. revolving charge accounts) to individuals for personal, family or household purposes.

• “With respect to a consumer credit sale, refinancing, or consolidation, including a revolving charge account, the parties may contract for a delinquency charge on any installment not paid in full within ten (10) days after its scheduled due date as follows: (a) an amount, not exceeding the greater of five percent (5%) of the unpaid portion of the scheduled installment or Five Dollars ($5.00), subject to adjustment pursuant to Section 1-106 of this title;” — Okla. Stat. tit. 14A, § 2-203(1), read November 6, 2026
• “A delinquency charge under paragraph (a) of subsection (1) of this section may be collected only once on an installment however long it remains in default.” — Okla. Stat. tit. 14A, § 2-203(2), read November 6, 2026
• “2-203(1)(a) $33.00 $34.00” — Okla. Dept. of Consumer Credit, Changes in Dollar Amounts – July 1, 2026 (Okla. Stat. tit. 14A, § 1-106), read November 6, 2026

Does Oklahoma want it agreed in advance?

Agreed in advance: yes, in the cases below. The delinquency charge is one the parties 'may contract for' (14A § 2-203); the 6% legal rate applies 'in the absence of any contract as to the rate' (tit. 15 § 266).

• “With respect to a consumer credit sale, refinancing, or consolidation, including a revolving charge account, the parties may contract for a delinquency charge on any installment not paid in full within ten (10) days after its scheduled due date as follows: (a) an amount, not exceeding the greater of five percent (5%) of the unpaid portion of the scheduled installment or Five Dollars ($5.00), subject to adjustment pursuant to Section 1-106 of this title;” — Okla. Stat. tit. 14A, § 2-203(1), read November 6, 2026
• “The legal rate of interest shall be six percent (6%) in the absence of any contract as to the rate of interest, and by contract parties may agree to any rate as may be authorized by law, now in effect or hereinafter enacted.” — Okla. Stat. tit. 15, § 266, read November 6, 2026

Homeowners and businesses in Oklahoma

Homeowner (individual, household purpose) credit sales fall under the consumer credit sale caps and the delinquency-charge limit; sales to organizations or for business are free to set any agreed credit service charge.

• “"consumer credit sale" is a sale of goods, services or an interest in land in which (a) credit is granted by a person who regularly engages as a seller in credit transactions of the same kind; (b) the buyer is a person other than an organization; (c) the goods, services or interest in land are purchased primarily for a personal, family or household purpose; (d) either the debt is payable in installments or a credit service charge is made;” — Okla. Stat. tit. 14A, § 2-104(1), read November 6, 2026
• “With respect to a sale other than a consumer credit sale, the parties may contract for the payment by the buyer of any credit service charge.” — Okla. Stat. tit. 14A, § 2-605, read November 6, 2026

Prompt payment on private construction in Oklahoma

No interest rate set — payment deadlines only. Private construction projects issued for bid (owner → prime → subcontractor); negotiated projects only partly. Private bid projects: if the owner did not state payment terms, monthly progress payments due within 28 calendar days after billing; subcontractors paid within 10 calendar days after the prime is paid (unless otherwise agreed). Private negotiated projects are outside subsection A. No interest on late payment found in § 820.

• “a. the owner shall make monthly progress payments, and b. payments shall be due within twenty-eight (28) calendar days after receipt of billing.” — Okla. Stat. tit. 15, § 820(A)(2), read November 6, 2026
• “Subcontractors shall be paid by the prime contractor within ten (10) calendar days of payment from the owner, or as otherwise agreed to by the parties.” — Okla. Stat. tit. 15, § 820(A)(4), read November 6, 2026
• “The provisions of subsection A of this section shall not be applicable to private negotiated projects.” — Okla. Stat. tit. 15, § 820(B)(1), read November 6, 2026

Work out a late charge in Oklahoma

Starts at Oklahoma's 6%, the rate when none was agreed, not a maximum.

What was not checked for Oklahoma

• Whether a one-payment service invoice with a late fee, but no installments or credit service charge, is a "consumer credit sale" in Oklahoma turns on 14A § 2-104(1)(d), and was not settled here.

Check Oklahoma's own text

Before you charge: read Okla. Stat. tit. 15, § 266 and the other Oklahoma texts quoted on this page, or ask a lawyer. As of November 6, 2026.

This is a plain-words summary of each state's own laws as of November 6, 2026, not legal advice. Rules have exceptions. Check the state's own text, linked on every state's page, or a lawyer before you charge a late fee or interest.

Compare Oklahoma with every state's answer, or with its neighbours just below.

Next door to Oklahoma

• Arkansas: depends if none agreed, 17% by agreement (not fully confirmed)
• Colorado: 8% if none agreed, depends by agreement
• Kansas: 10% if none agreed, depends by agreement
• Missouri: 9% if none agreed, depends by agreement
• New Mexico: up to 15% if none agreed, depends by agreement
• Texas: 6% if none agreed, depends by agreement

Official sources for Oklahoma

• Okla. Stat. tit. 15, § 266 — read November 6, 2026
• Okla. Stat. tit. 14A, § 2-201(2) — read November 6, 2026
• Okla. Dept. of Consumer Credit, Changes in Dollar Amounts – July 1, 2026 (Okla. Stat. tit. 14A, § 1-106) — read November 6, 2026

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