Missouri Late Fee Calculator
Work out interest on an overdue B2B invoice under Missouri law. The legal default rate — what applies when the contract is silent — is 9%, and the statute is quoted verbatim below. All math runs locally in your browser.
On written contracts, from the due date; on open accounts, after the debt is due AND payment has been demanded.
Late fee breakdown
- Interest owed
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- Daily rate
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- Total (invoice + interest)
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Still unpaid? Generate a formal demand letter — it computes the interest and cites Missouri's statute (RSMo 408.020, 408.030, 408.035) for you.
What Missouri law actually says
Notwithstanding the provisions of any other law to the contrary, it is lawful for the parties to agree in writing to any rate of interest, fees, and other terms and conditions in connection with any: (1) Loan to a corporation, general partnership, limited partnership or limited liability company; (2) Extension of credit primarily for agricultural, business, or commercial purposes;
Quoted verbatim from the linked official source — not our paraphrase. How we source and re-check every row is documented in the data methodology.
Maximum late fee in Missouri — written B2B contracts
No statutory cap
RSMo 408.035 lets parties agree in writing to any rate of interest and fees on a loan to a corporation, general partnership, limited partnership or LLC (1) and on any extension of credit primarily for agricultural, business or commercial purposes (2) — no dollar minimum, so B2B trade credit is outside the 10% ceiling regardless of amount or of whether the debtor is an entity or a sole proprietor. The exemption requires a written agreement; with no writing, the 9% default under 408.020 applies.
Basis: RSMo 408.035(1)-(2). Compare all 51 jurisdictions on the full state table and the cap-regime map.
B2B invoices only — not rent, not consumer debt
Everything on this page is about business-to-business invoices. Residential rent late fees live in Missouri's landlord-tenant law and consumer credit has separate, stricter rules — two different bodies of law. The distinction is explained in B2B invoice late fees vs. residential rent.
Use this data
Missouri's row — rate, cap, citation, verbatim quote, verification date — is part of our open 51-jurisdiction dataset: CSV · JSON (CC BY 4.0, cite myinvoicetemplate.com). Set late-fee terms on your next invoice with the free invoice generator, or state them clearly using the wording guidance in the payment terms guide.
Missouri late fee FAQ
Can I charge late fees on overdue invoices in Missouri?
Yes — on business-to-business invoices. If your contract or invoice states a late-fee rate, that rate governs (subject to the cap rules below). If nothing was agreed: 9%. On written contracts, from the due date; on open accounts, after the debt is due AND payment has been demanded. Statute: RSMo 408.020, 408.030, 408.035, verified 2026-08-19. Consumer and rent debts follow separate laws.
What is the maximum late fee I can charge in Missouri?
For a written B2B contract: 10% cap (or the state-published market rate if higher — Q3 2026 market rate is 7.99%, so 10% governs). Exempt: loans to corporations/partnerships/LLCs and any extension of credit primarily for agricultural, business, or commercial purposes (no dollar minimum) — any agreed written rate. Basis: RSMo 408.035(1)-(2). The full cap analysis is in the section above; this covers business-to-business deals only — consumer credit has stricter separate caps.
What interest applies if my contract doesn't mention late fees in Missouri?
The statutory default rate of 9%. On written contracts, from the due date; on open accounts, after the debt is due AND payment has been demanded. Statute: RSMo 408.020, 408.030, 408.035 (verbatim quote on this page, verified 2026-08-19).
Does this cover rent, apartment, or consumer late fees in Missouri?
No. This page covers business-to-business invoices only. Residential rent late fees are governed by Missouri's landlord-tenant law, and consumer credit for personal, family, or household purposes has its own stricter caps and disclosure rules. Those are different statutes than the commercial-interest law cited here.
Where does this data come from, and when was it verified?
Every figure on this page comes from our 51-jurisdiction dataset: each row researched against the controlling statute or the state's official current-rate page, independently re-checked, and stamped with its own verification date — Missouri's row was last verified 2026-08-19. The operative legal text is quoted verbatim on this page with a link to the official source, the methodology is public, every verification pass is logged in the changelog, and the full dataset is downloadable (CC BY 4.0).
Not legal advice. This page summarizes Missouri's commercial-interest statute for general information, with the verification date shown above — it tells you when we last confirmed the figures, not that they are still current today. Statutes change and courts interpret them; verify the cited statute at the official source, or ask a licensed attorney in your state, before charging or demanding interest.