Louisiana late fee law

Set by formula or published periodically rather than fixed in statute, so it must be looked up for the period in question.

Louisiana has no fixed statutory number: under La. R.S. 9:3500 (the successor to former Civil Code art. 2924), legal interest on sums that are the object of a judicial demand is the judicial interest rate fixed annually under La. R.S. 13:4202 - the Federal Reserve discount rate ascertained on the first business day of October plus 3.25 percentage points, published by the Commissioner of Financial Institutions (7.5% per annum for calendar year 2026 per the Louisiana Office of Financial Institutions). Verified on legis.la.gov and ofi.la.gov.

Conventional (agreed) interest must be fixed IN WRITING and cannot exceed 12% per annum - but La. R.S. 9:3500 expressly provides that this limitation does not apply to loans made, or deferral of payment of an obligation, for commercial or business purposes, so B2B transactions are effectively exempt from the 12% usury cap. Consumer credit transactions are governed separately by the Louisiana Consumer Credit Law.

public+private-construction

Public works: public entities must make progressive/final payments within 45 days of a certified payment request; wrongfully withheld amounts bear interest of 0.5% per day (capped at 15%) plus reasonable attorney fees (La. R.S. 38:2191). Private (non-residential) construction: contractors must pay subcontractors/suppliers within 14 days of receiving owner payment; failure without reasonable cause incurs a penalty of 0.5% per day of the amount due, capped at 15%, plus reasonable attorney fees (La. R.S. 9:2784). No act covering ordinary private non-construction commercial invoices was found.

Because conventional interest above the legal rate must be fixed in writing (testimonial proof is inadmissible, R.S. 9:3500), late-interest clauses on Louisiana invoices should be in a signed writing. Louisiana's open account statute (La. R.S. 9:2781, commonly invoked for unpaid trade invoices) allows recovery of reasonable attorney fees after a proper written demand - verify current text with counsel. Agreed flat late fees are otherwise judged under Louisiana's stipulated-damages rules (La. Civ. Code arts. 2005 et seq.).