Late fee calculator for invoices
An invoice is overdue. Type the amount and the due date, pick the rule from your terms, and you get the fee, the new total and a sentence to paste into the reminder.
Last updated 14 October 2026
How the fee is worked out
Days late are counted from the day after the due date to the date you set (today by default). Then, depending on the rule:
- Percent per month: amount × rate ÷ 30 × days late. A month is taken as 30 days so a half month costs half, which is what a judge would also expect.
- EU statutory: amount × (reference rate + 8%) ÷ 365 × days late, plus the €40 fixed recovery sum once. Only for business-to-business invoices.
- UK statutory: amount × (base rate + 8%) ÷ 365 × days late, plus £40, £70 or £100 depending on the invoice size.
- Flat fee: the fee once, from day one late.
The new total is the amount plus the fee. "Per day from here" is what every further day adds; put that number in the reminder, it works better than the total.
One example
| Input | Value |
|---|---|
| Invoice | $1,850, due 26 September |
| Today | 8 October, so 12 days late |
| Terms | 1.5% a month |
| Fee | $1,850 × 1.5% ÷ 30 × 12 = $11.10 |
| New total | $1,861.10, and $0.93 more each day |
Eleven dollars is not the point. The point is that the reminder now has a number that grows, and the client's accountant has a reason to move it to the top of the pile.
Before you add it to an invoice
- It has to be in writing before the invoice is due. In your terms, your quote, or on the invoice itself. A fee that appears for the first time in the reminder is unenforceable almost everywhere.
- Keep it boring. 1 to 2% a month, or the statutory rate. A 5% a month fee looks like a penalty and courts in most countries cut it down.
- Private clients are different. Statutory business rates (EU, UK) do not apply to consumers; use a modest contractual rate and check your local consumer rules.
- Say it once, then stop. Mention the fee in the first reminder. Repeating it in every email reads as a threat and slows payment down.
Questions people ask
Can I charge a late fee on a freelance invoice?
Yes, if the client agreed to it before the invoice fell due: in your terms, the quote, or on the invoice. In the EU and UK you can also charge statutory interest on business invoices without any clause at all. For private clients you need a clause and a reasonable rate.
What is a normal late fee?
1 to 2% of the invoice per month is the common range in freelance terms worldwide. Statutory rates are the reference or base rate plus 8 points a year, which comes to roughly 1% a month. Flat fees of $25 to $50 are common for small invoices.
How is the EU late payment interest calculated?
Directive 2011/7/EU: the ECB reference rate at the start of the half-year plus at least 8 percentage points, charged per day on the unpaid amount, plus a fixed €40 recovery sum per invoice. It applies to business-to-business invoices; countries may set a higher rate. Czech Republic uses the CNB repo rate plus 8 points.
How does UK statutory interest work?
Late Payment of Commercial Debts Act: Bank of England base rate plus 8% a year, from the day after the due date, plus a fixed sum per invoice: £40 under £1,000, £70 from £1,000 to £9,999, £100 from £10,000. The base rate used is the one from 31 December or 30 June before the invoice fell due.
Is there a statutory late fee in the US?
No federal rule. You charge what the contract says, subject to state usury limits, which for commercial invoices are rarely an issue at 1 to 1.5% a month. Without a clause you can ask, but you cannot enforce.
Does charging a late fee make clients pay faster?
The clause does more than the fee. Clients with a late fee in the terms pay sooner because their bookkeeper sees it. Charging it is a judgment call: for a good client who slipped once, waive it and say so; for a repeat offender, charge it and keep the money.
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