How to tell a customer you are charging a late fee

Break the numbers out in the email: the interest, the fixed fee, the new balance, and the deadline that makes the whole charge disappear if they settle the original. A late fee email that states one lump sum reads as a penalty. One that shows the working and offers a way out reads as a process.

Show the working

Itemise it: interest, fixed fee, new balance, and the deadline that cancels the charge. A lump sum looks like something a person decided this morning. An itemised charge looks like something your system produced, and only one of those is worth arguing with.

An itemised charge reads as system output. A lump sum reads as a decision someone made this morning, and a decision can be argued with.

The warning email, before the charge applies

The message that collects the most money is the one sent before any charge exists.

It is a diary note with a consequence attached, sent while there is still nothing to argue about.

The late fee email, with the charge itemised

The email that applies the charge should state interest, fixed fee, charge total, new balance, daily accrual, and the deadline that cancels it if they settle the original. Six figures, and the customer can check every one.

The contact history and the daily accrual figure do most of the work here, and the daily figure matters more than the total because it is what makes waiting feel expensive.

The email that cancels the charge once they pay is in waiving a late payment fee.

When they refuse to pay it

Some customers will pay the invoice and simply ignore the charge. That is usually fine and is often the outcome you wanted. Some will write back and refuse.

Point at the clause, not at their behaviour. The moment the exchange becomes about how patient you have been, you have moved from a contractual position to an emotional one, and the contractual position is the stronger of the two.

The final notice email before escalation

A final notice states the accrued total, the full contact history, a specific date, and what happens after it. It does not threaten, and it is never followed by a second final notice.

Two rules for this one. State a date, and mean it, because a final notice that is followed by another final notice teaches the customer that none of them are real. And offer the alternative, because a lot of accounts that reach this stage are cash flow problems rather than refusals, and a payment plan collects more than a legal letter does.

What comes after this is a formal letter before action. The full sequence is set out in our invoice escalation ladder.

Never fee a disputed invoice

Never apply a late fee to a genuinely disputed invoice. A queried invoice is not late, it is unresolved, and charging it hands the customer a legitimate grievance to raise instead of the payment.

If a customer has genuinely queried an invoice, the invoice is not late in any useful sense. It is unresolved. Applying a charge to it does three things, all bad: it tells them you were not listening, it gives them a legitimate grievance to raise instead of the payment, and if the dispute turns out to be valid, you charged interest on money you were never owed.

Pause the account, resolve the query, then resume. If part of the invoice is agreed and part is disputed, ask for the agreed part now and hold the charge on the rest.

A vague delay is not a dispute. "We are waiting on approval" and "we do not pay until month end" are stalling, and the charge should apply. A specific objection to a specific line is a dispute, and it should be fixed before anything else happens.

What your market allows

The wording changes slightly depending on where your right to charge comes from.

In the UK and the EU the right is statutory and automatic on business-to-business invoices, so you can reference the legislation as well as your terms. That is a strong position and it is worth stating plainly: the charge exists whether or not the contract mentions it.

Almost everywhere else, including Australia, New Zealand, Canada, the United States, South Africa and Singapore, the right is contractual. The email must reference the clause in your terms, because the clause is the entire basis of the charge. "In line with clause 6 of our terms of business, signed 3 March 2025" is doing real work in those markets, not just sounding formal.

How Paidnice does this, and how simple it is

The reason these emails do not get sent is rarely that people cannot write them. It is that sending one requires deciding to, on a specific morning, about a specific customer.

• The notification is part of the fee policy. When a charge is applied, the customer is told automatically, with the figures already itemised.
• The numbers fill themselves in. Interest to date, the fixed charge, the new balance and the invoice reference are merged into the message, so nothing is typed by hand and nothing is wrong.
• Reminders run before the charge as well as after, so the warning email goes out on schedule rather than when someone remembers.
• Filter by invoice reference, or move the customer to another group, which is how a disputed invoice or a disputed account comes out of the sequence without switching the whole policy off.

Setting it up is one policy and one message template on one customer group.

Common questions

Do I have to warn a customer before charging a late fee?
Legally, usually not, and in the UK the statutory right applies without notice. Practically, always. The warning collects more invoices than the charge does, and it removes the "nobody told us" reply.

What if they say they never agreed to late fees?
In the UK and EU, point to the statutory right, which applies regardless of the contract. Elsewhere, point to the clause and the date they accepted it. If there is no clause, you have a terms problem rather than an email problem.

Should the fee email come from a person or an accounts address?
A person, with a real reply address. An accounts inbox invites being ignored, and the whole point of the message is that someone is watching this account.

How long should I give them to avoid the charge?
Seven to ten calendar days. Long enough to clear an approval process, short enough to fall inside one payment run.

Can I charge a fee and still keep the relationship?
Yes, and consistency is what makes that possible. A charge that applies to everyone every time is a policy. A charge that appears only when someone is annoyed is personal, and that is what damages relationships.

Written by

Denym Bird

Co-founder & CEO of Paidnice

Denym is a software entrepreneur and writes about accounts receivables management for small business.

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