Interest on unpaid invoices in Louisiana: a floating rate if no rate was agreed; the most you can set depends on the deal

Louisiana's rate when no rate was agreed

See the state's words below. Civil Code art. 2000: damages for late payment of money are interest at the agreed rate or, absent agreement, the legal rate fixed by R.S. 9:3500, which points to the judicial rate of R.S. 13:4202.

How the rate moves: Fed discount rate on first business day of October + 3.25 points, for the next calendar year.

• “When the object of the performance is a sum of money, damages for delay in performance are measured by the interest on that sum from the time it is due, at the rate agreed by the parties or, in the absence of agreement, at the rate of legal interest as fixed by R.S. 9:3500.” — La. Civ. Code art. 2000, read November 6, 2026
• “Legal interest is fixed at the following rates, to wit: (1) At the rate fixed in R.S. 13:4202 on all sums which are the object of a judicial demand, whence this is called judicial interest” — La. R.S. 9:3500(B), read November 6, 2026
• “The effective judicial interest rate for the calendar year following the calculation date shall be three and one-quarter percentage points above the discount rate as ascertained by the commissioner.” — La. R.S. 13:4202(B)(1), read November 6, 2026
• “January 1, 2026 to December 31, 2026 | 7.50%” — Louisiana Office of Financial Institutions, Judicial Interest Rates, read November 6, 2026

The most you can set in Louisiana

For a homeowner: It depends: see La. R.S. 9:3500(C). R.S. 9:3500(C)(1) caps conventional interest at 12% a year and requires it in writing.

For a business customer: No cap under R.S. 9:3500 for obligations for commercial or business purposes. R.S. 9:3500(D) says the article does not apply to a loan for business purposes or to deferring payment of an obligation for business purposes.

• “The amount of the conventional interest cannot exceed twelve percent per annum. The same must be fixed in writing; testimonial proof of it is not admitted in any case.” — La. R.S. 9:3500(C)(1), read November 6, 2026
• “The provisions of this Article shall not apply to a loan made for commercial or business purposes or deferring payment of an obligation for commercial or business purposes.” — La. R.S. 9:3500(D), read November 6, 2026

Late fees in Louisiana

What the text says: Consumer credit transactions: a delinquency charge may be contracted for on a payment not paid in full within 10 days after due — the greater of 5% of the unpaid installment or $10 (or the permitted deferral charge). Consumer credit transactions under the Louisiana Consumer Credit Law (e.g. a consumer credit sale: credit service charge + two and more installments). It depends: see La. R.S. 9:3527 and 9:3516. A plain invoice due in one payment with no credit service charge is not a consumer credit sale as defined.

• “The parties to a consumer credit transaction may contract for the payment of a delinquency charge on any installment or other regular payment not paid in full within ten days after its scheduled or deferred due date in either one of the following amounts: (1) Five percent of the unpaid amount of the delinquent installment, or ten dollars, whichever is greater.” — La. R.S. 9:3527(A), read November 6, 2026
• “A 'consumer credit sale' is the sale of a thing, other than the sale of religious periodicals, books, and other religious materials by bona fide religious associations, or immovable property, in which a credit service charge is charged and the purchaser is permitted to defer all or part of the purchase price or other consideration in two or more installments excluding the down payment when the thing is purchased primarily for personal, family, or household purposes, and the purchaser is a person other than an organization.” — La. R.S. 9:3516, read November 6, 2026

Does Louisiana want it agreed in advance?

Agreed in advance: yes, in the cases below. Contract interest above the legal rate must be fixed in writing (R.S. 9:3500(C)(1)); consumer credit delinquency charges are what the parties 'may contract for' (R.S. 9:3527). Without agreement, only legal interest runs (Civ. Code art. 2000).

• “The same must be fixed in writing; testimonial proof of it is not admitted in any case.” — La. R.S. 9:3500(C)(1), read November 6, 2026
• “at the rate agreed by the parties or, in the absence of agreement, at the rate of legal interest as fixed by R.S. 9:3500.” — La. Civ. Code art. 2000, read November 6, 2026

Homeowners and businesses in Louisiana

Homeowner: 12% conventional cap in writing, or Consumer Credit Law charges if the deal is a consumer credit sale; business customer: R.S. 9:3500 cap does not apply. See R.S. 9:3500(C), (D) and R.S. 9:3516/3527.

• “The provisions of this Article shall not apply to a loan made for commercial or business purposes or deferring payment of an obligation for commercial or business purposes.” — La. R.S. 9:3500(D), read November 6, 2026

Prompt payment on private construction in Louisiana

It depends: see La. R.S. 9:2784. 1.5% of the unpaid amount per month.

• “An unpaid amount as described in this Section shall incur a penalty at the rate of one and one-half percent of the unpaid amount per month.” — La. R.S. 9:2784, read November 6, 2026
• “a written contract between an owner and a contractor for improvements on or construction of a single-family residence may provide that the payment required” — La. R.S. 9:2784, read November 6, 2026

Work out a late charge in Louisiana

Set your own rate.

What was not checked for Louisiana

• The consumer credit exception in La. R.S. 9:3500(C)(4)(b) was seen only in a summary, not read word for word, so it is not quoted here.
• Louisiana's rate for 2027, set each October, was not yet on the Office of Financial Institutions page when this was checked.

Check Louisiana's own text

Before you charge: read La. Civ. Code art. 2000 and the other Louisiana 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 Louisiana with every state's answer, or with its neighbours just below.

Next door to Louisiana

• Arkansas: depends if none agreed, 17% by agreement (not fully confirmed)
• Mississippi: 8% if none agreed, depends by agreement (not fully confirmed)
• Texas: 6% if none agreed, depends by agreement

Official sources for Louisiana

• La. Civ. Code art. 2000 — read November 6, 2026
• La. R.S. 9:3500(B) — read November 6, 2026
• La. R.S. 13:4202(B)(1) — read November 6, 2026
• Louisiana Office of Financial Institutions, Judicial Interest Rates — read November 6, 2026
• La. R.S. 9:3527(A) — read November 6, 2026
• La. R.S. 9:3516 — read November 6, 2026
• La. R.S. 9:2784 — read November 6, 2026

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