How to charge late fees on invoices: policy, wording and math

Here is how to charge late fees: decide your policy, put it in your contract or invoice terms before the work starts, state the rate, the start date and any grace period, then calculate the fee on a clearly labeled line. For example, 1.5 percent per month on a 1,000.00 USD invoice 45 days late is 30.00 USD.

Should you charge late fees at all?

A late fee does two jobs. It discourages clients from putting your invoice at the bottom of the pile, and it compensates you a little for the cost of waiting. It does not usually make you rich. The real value of a late fee clause is that clients who read it tend to pay on time.

There are good reasons not to charge one too. If a long-term client is a day late once, a fee can cost more in goodwill than it brings in. Many freelancers include the clause and waive it the first time, on the basis that having the right is what matters. That is a legitimate choice, as long as you do it on purpose and on your terms.

Before you decide, check the rules where you work. Late fees and interest are regulated differently by country, by US state and by type of customer. Some places cap interest rates or limit what can be added to a consumer bill, and others set statutory rates for business debts. This page is general information, not legal advice.

What the law says in a few places

The rules differ widely, so treat these as examples and verify your own.

• United Kingdom, business customers. GOV.UK says the statutory interest on late commercial payments is 8 percent plus the Bank of England base rate, and that it does not apply if the contract sets a different rate. GOV.UK also lists fixed sums a supplier can charge for recovering a late commercial payment: 40 pounds for debts up to 999.99 pounds, 70 pounds for debts from 1,000 to 9,999.99 pounds, and 100 pounds for debts of 10,000 pounds or more, charged once per payment.
• United States. There is no single national rule for late fees on business invoices. Interest limits and fee rules vary by state, and consumer sales are often treated differently from business sales. Look at your state’s attorney general or consumer protection website, or ask an adviser.
• Elsewhere. Many countries set their own default late payment rules. Check with a local authority or accountant.

In every case, the safest base is the same: the client agreed to the fee in writing before the work was done.

How to charge late fees, step by step

Late fee wording you can adapt

Good wording answers four questions: when does the fee start, how is it calculated, is there a cap, and how is it billed.

Invoices are due 30 days from the invoice date. If payment is not received within 5 days after the due date, a late fee of 1.5% of the unpaid balance applies for each month or part of a month the balance remains unpaid, up to a maximum of 10% of the original invoice amount. Late fees are shown on a separate invoice that refers to the original.

On the invoice itself, a short version is enough: “Late payments are subject to a fee of 1.5% per month, as agreed in the project contract dated 3 October 2026.” Match the invoice wording to the contract exactly. If the two disagree, the client will quote the one that suits them.

Keep the clause in plain language. Avoid threats, and avoid terms you will not enforce. Review it with a lawyer once if your contracts are large or you work across borders.

A worked example: 1,000 dollars, 45 days late

A freelancer invoices 1,000.00 USD with Net 30 terms and a clause that charges 1.5 percent per month or part of a month, simple interest, no grace period. The client pays 45 days after the due date.

The example shows why wording matters. “Per month or part of a month” gives 30.00 USD. “Prorated by day” gives 22.50 USD. Neither is wrong, but the client needs to know in advance which one you mean. The late fee calculator lets you test both.

Flat fee, percentage or interest?

Method	How it works	Good for	Watch out for
Flat fee	A fixed amount, such as 25.00 USD, once the invoice is late	Small invoices, simple wording	A flat fee can be large compared to a small invoice, which may look punitive
One-time percentage	A single charge, such as 5 percent, when the invoice becomes late	Easy to explain	Does not grow over time, so there is less pressure after the first day
Simple monthly interest	A percentage each month, such as 1.5 percent	Most common, grows with delay	Needs a clear rule for part-months
Compound interest	Interest on interest	Rarely needed	Harder to explain, and more likely to run into legal limits

For most small businesses, simple monthly interest with a grace period and a cap balances fairness and pressure.

Mistakes to avoid

• Adding a fee that was never agreed. This is the most common cause of disputes.
• Choosing a rate that is too high. An aggressive rate can break local limits and damage the relationship.
• Vague wording. “Reasonable late charges may apply” gives you nothing to calculate and the client nothing to anticipate.
• No grace period. A fee that starts at midnight on the due date feels harsh for an honest delay.
• Changing the original invoice. Issue a separate fee line or a new document.
• Applying it unevenly. Charging one client and waiving it for another without a reason can cause friction. Waive on purpose and keep notes.
• Using the fee as a threat. State it factually. Tone matters, as covered in how to ask for payment.
• Skipping the follow-up. A late fee only works if you also send the reminder.

Checklist: late fee policy

• You have checked the rules for your state or country and customer type.
• The fee is in your contract or quote before work begins.
• The rate, start date, grace period and cap are stated.
• You know whether part-months count as full months, and the wording says so.
• The invoice repeats the clause and refers to the contract.
• Fees are billed on a separate line or invoice with the calculation shown.
• You have a plan for when you waive the fee, and you record each waiver.
• Reminders go out before the fee starts, not only after.

Where PayToMe fits

The late fee calculator is live and free today, and so is the invoice generator. You can also create, send and get paid for invoices in PayToMe, now in public beta. Automatic late fees and smart reminders, which would apply your policy and send the notices for you, are in development. For related setup, see invoice payment terms.

Sources

This is general information, not legal advice. The UK statutory interest rate of 8 percent plus the Bank of England base rate, and the note that it does not apply if the contract sets another rate, come from GOV.UK: Charging interest on late commercial payments. The fixed recovery sums of 40, 70 and 100 pounds come from GOV.UK: Claim debt recovery costs on late payments. Rules for US states and other countries are not covered here and differ widely, so check with your state or national authority or a qualified professional. The example rates and clause wording are illustrations, not recommendations.