Invoice AI · Guides · Terms

How to charge late fees on invoices, legally

A late fee is allowed, useful and often misused. Here's how to set one that holds up and doesn't cost you the customer.

3 min read · Updated Nov 3, 2026

Key takeaways
  • A late fee is only enforceable if the customer agreed to it before the work: in the quote or contract.
  • Typical: 1 to 1.5% per month (12 to 18% a year), or a flat $25 to $50 after a grace period.
  • Some states cap interest on consumer debts lower than on business debts. Check yours.
  • A fee is a lever for terms, not a revenue line. Waive it the first time if they pay promptly after a reminder.

Can a small business charge late fees?

Yes, in every US state, with two conditions. The customer must have agreed to the fee before the work (so it belongs in the quote or contract, not just the invoice), and the rate must be within your state's limits. Business-to-business fees have more room than fees charged to consumers.

This isn't legal advice; the rules differ by state and we're not lawyers. For anything that might end up in court, have a local attorney read your terms once.

How much is reasonable

Pick one approach and use it for everyone. Fees that appear for some customers and not others are the ones that get argued.

Wording that holds up

Invoices unpaid 14 days after the due date carry a late charge of 1.5% per month on the outstanding balance, from the due date, until paid.
A late fee of $35 applies to invoices unpaid 14 days after the due date.

Say it in the quote. Repeat it on the invoice. Mention it, kindly, in the second reminder: "Just so you know, a 1.5% late charge applies after the 29th; I'd rather not add it."

State rules to watch

Interest and late-fee limits are set by state usury and consumer laws. A few examples of the kind of thing to check (verify for your state and year):

A quick search for "[your state] late fee limit invoice" will find the number. If in doubt, 1 percent per month is safe almost everywhere.

When not to charge the fee

Fees are for the customer who ignores you, not the one who forgot. If a customer pays within a few days of a reminder, waive it and tell them you did. You'll get paid faster next time, and you'll keep the customer. Charge it for the ones who go silent past the final reminder; that's what it's for.

Fees vs. the thing that actually gets you paid

Late fees change behaviour for maybe one customer in ten. Reminders change it for seven in ten. Set a fair fee, mention it once, and spend your effort on the reminder ladder. Invoice AI runs the reminders and notes the fee in the final notice, without ever threatening.

Questions people ask

Is it legal to charge late fees on invoices?

Yes in every US state, if the customer agreed to the fee before the work and the rate is within state limits. We're not lawyers; check your state for the exact cap.

How much can I charge as a late fee?

1 to 1.5% per month, or a flat $25 to $50 after a grace period, is typical and rarely challenged. Higher rates risk being treated as a penalty.

Can I add a late fee if it wasn't in the quote?

You can ask, but it's usually unenforceable and often angers the customer. Put it in the quote for next time.

Should I waive late fees?

Waive it for anyone who pays promptly after a reminder, and tell them. Keep it for customers who go silent past the final notice.

Keep reading

Get paid without chasing.

Watch a 20-second demo, then add your own invoice.

No card needed to try.