Invoice Late Fee Calculator
Work out what an overdue invoice is now worth, how fast it is growing, and send a reminder that is firm without being an argument.
Total now due
$2,450
Growing by $1.20 a day while it stays unpaid.
What is owed
- Invoice$2,40098%
- Interest$251%
- Admin fee$251%
If it stays unpaid
- Late charges at 30 days$61.00
- At 60 days$97.00
- At 90 days$133.00
- Total due at 90 days$2,533including invoice
Copy-ready payment reminder
Subject: Overdue invoice INV-0042 — $2,450 now due Hello, Invoice INV-0042 for $2,400 was due 21 days ago and is still showing as unpaid on my side. Under the agreed payment terms of 14 days, late payment carries a 1.5% monthly interest charge and a $25 administrative fee. That currently brings the balance to: Original invoice: $2,400 Administrative fee: $25 Interest (21 days): $25 Total now due: $2,450 Interest continues to accrue at $1.20 a day. If the invoice has been queried or is stuck in an approval step, tell me where it is and I will help move it along. If payment clears this week I am happy to waive the late charges entirely and settle the original amount. Thank you,
Read the full guide
Late payment is a process problem, not a personality problem
The instinct when an invoice goes unpaid is to take it personally and then, oddly, to become apologetic about mentioning it. Both reactions make the situation worse. In the large majority of cases the invoice is not being refused; it is sitting in an approval queue, attached to the wrong purchase order, addressed to somebody who left, or waiting for a payment run that happens on the 25th. None of that resolves itself, and none of it is improved by waiting another fortnight to be polite.
So the correct response is administrative. Work out precisely what is owed, state it plainly with the terms that were agreed, offer to help unblock it, and give a concrete next date. That is what the reminder below does.
What to charge, and why it works even when you do not collect it
A monthly interest charge of 1 to 2 percent on the outstanding amount, plus a small fixed fee for the cost of chasing, is ordinary commercial practice and reads as professional rather than aggressive. In several jurisdictions statutory interest on commercial debt applies whether or not it appears in your contract, and in others it needs to be written into your terms to be enforceable, so put it in writing on every contract and every invoice from now on.
Here is the practical truth: the fee's value is mostly not the money. It is that a stated consequence changes where your invoice sits in a queue. Suppliers with late fees get paid before suppliers without them, because somebody's job is to avoid unnecessary charges. Many freelancers state the fee routinely and waive it routinely, and still get paid faster than they used to.
A sequence that resolves most of these
- Day 1 overdue. A short, friendly note with the invoice attached again. No apology, no accusation. Ask whether it reached the right person.
- Day 7. The reminder from this page, with the charges calculated and the offer to waive them for prompt payment. Send it to your contact and, where you reasonably can, to accounts payable directly.
- Day 14. A phone call. Email is easy to defer; a conversation is not. Ask for a specific payment date and repeat it back in writing afterwards.
- Day 21. Pause further work in writing, stating what resumes on payment. This is the step people avoid and the step that works.
- Day 30 and beyond. A formal final demand, then small-claims or a collection service depending on the amount and where you both are.
Preventing the next one
Nearly every chronic late payer can be handled in advance: take a deposit before starting, invoice immediately on delivery rather than at the end of the month, put terms of 14 days on the invoice itself in plain language, name the late fee, and ask during onboarding who actually approves payments and when their payment run falls. Those five small habits remove most of this work permanently — and the deposit alone removes the worst outcome, where you have delivered everything and hold no leverage at all.
Frequently asked questions
- Can I charge a late fee if it was not in the contract?
- Enforcing one is much harder without written terms, and in several places statutory interest applies anyway on commercial debts. Practically, the fee's value is as a stated consequence rather than as money you chase, so put it in every future contract and invoice.
- What is a reasonable late fee?
- A flat administrative charge plus 1 to 2 percent monthly interest on the outstanding amount is standard for small suppliers. Anything punitive tends to be unenforceable and damages the relationship without improving payment.
- When should I actually send a reminder?
- Day one after the due date, politely and without apology. Most late payments are administrative rather than deliberate, and an invoice that has been queried early gets paid in the next payment run.
- Should I waive the fee if they pay immediately?
- Often yes, and say so explicitly: the fee applies, and you will waive it if payment clears this week. That converts a confrontation into an incentive.
- What if they still do not pay?
- Stop work, put the position in writing with a final date, and treat further work for that client as a decision rather than an obligation. A client who will not pay an overdue invoice rarely becomes one who will pay the next one.