Guide

How much late fee should you charge on an overdue invoice?

A percentage-based late fee is usually too small to matter on small tickets. Here's the maths behind a two-tier structure — a flat fee first, interest second — and the exact wording that makes it collectable.

The standard advice doesn't work on small invoices

Most templates tell you to charge 1.5% to 2% per month on overdue invoices. It sounds reasonable and it's what everyone copies from everyone else. The problem is the number it actually produces.

On a $1,200 invoice, 1.5% a month is $18. Your customer looks at that, shrugs, and pays whenever they get round to it. An $18 penalty doesn't beat the mental cost of writing a cheque, logging into a banking app, or remembering to do it at all. For most residential and small commercial jobs, percentage-based late fees are decorative, not functional.

The crossover point: when percentage actually beats a flat fee

A flat fee works because it's a fixed, visible number that doesn't shrink to nothing on small jobs. Compare a $35 flat fee to 1.5% per month across invoice sizes:

Invoice amount	1.5%/month fee	$35 flat fee	Which wins for you
$500	$7.50	$35	Flat fee, by a mile
$1,200	$18	$35	Flat fee
$2,000	$30	$35	Flat fee
$2,333	$35	$35	Crossover
$5,000	$75	$35	Percentage
$10,000	$150	$35	Percentage

The crossover is $2,333. Below that, a flat fee charges more and is easier for the customer to understand. Above it, percentage interest starts to sting more than a flat fee would. Most jobs from plumbers, electricians, HVAC techs and handymen sit well under that line — which is why a flat rebilling fee, not interest, should be your first move.

The two-tier structure that actually works

Don't pick one mechanism. Stack them so the fee grows the longer the invoice sits unpaid:

• Day 15 (first late stage): flat rebilling fee of $35–$50, charged once. This covers your admin time — reissuing the invoice, sending a reminder, updating your books — and it's large enough to notice on any invoice under about $2,300.
• Day 30 onward: 1.5% per month (18% annualised, or whatever your state caps it at) on the outstanding balance, compounding or simple depending on what you state in your terms. By day 30 the balance that matters is often larger anyway — the customer has ignored two reminders, and interest starts to add up meaningfully the longer it runs.

Worked example on a $2,800 invoice, unpaid at day 45:

• Day 15: $40 flat rebilling fee added. Balance is now $2,840.
• Day 30–45: 1.5% per month on $2,840 for roughly half a month ≈ $21.
• Total owed at day 45: approximately $2,861.

That's a real number a customer notices, built from two mechanisms that are each individually defensible and easy to explain over the phone.

The exact wording to put on your invoice and contract

A late fee is only enforceable if the customer agreed to it before the work happened. Use this pattern, adapted for your state's usury and late fee rules (check with your accountant or a local business attorney — limits vary):

Contract clause (signed before work starts): "Invoices are due within [14/30] days of the invoice date. A late rebilling fee of $[35–50] will be applied to any invoice unpaid 15 days after the due date. Interest of 1.5% per month will accrue on any balance, including fees, that remains unpaid 30 days after the due date."

Invoice footer (printed on every invoice, not just the overdue ones): "Payment due within [X] days. Late fees apply per the terms of your service agreement — see contract."

The wording matters less than where it appears. Put the same clause in both places, word for word, so there's no gap between what the customer signed and what shows up on the bill.

Three conditions that make a late fee collectable, not decorative

1. Signed before work starts. A late fee added to an invoice after the job is done is a request, not a term. Get it into the estimate, work order or service agreement the customer signs upfront. If you don't currently get signatures before starting work, that's the gap to close first — a simple line in your intake process fixes it, and it's worth building into a standard operations checklist alongside deposit and cancellation terms.
2. Printed on every invoice. Consistency is what a small claims judge or a customer's credit card dispute team will look for. If half your invoices carry the clause and half don't, you've undermined your own position on the ones that do.
3. Never applied retroactively. Don't add a late fee to an invoice from six months ago because you've just started enforcing your policy. Apply it going forward, from the date the new terms took effect, to new work only. Retroactive fees are the fastest way to lose a dispute and a customer in the same conversation.

The chase economics: when it's cheaper not to chase

Late fees only matter if pursuing the money doesn't cost more than the fee recovers. Work out your own hourly cost with the hourly rate calculator before you spend an afternoon on the phone.

At an effective cost of $85 an hour — a reasonable blended rate once you count your time as billable — two hours chasing a payment (calls, texts, a follow-up visit, admin) costs you $170. That's before you've factored in the late fee itself, which might only be $35–$50.

• Above roughly $400 outstanding: chasing is worth it. The debt is large enough that recovering it, even with a couple of hours of your time, still nets you money.
• Below roughly $400 outstanding: a payment plan usually beats chasing. Offer two or three instalments by text or email, skip the late fee argument, and get most of the balance moving without burning billable hours you can't recover.

The $400 threshold isn't fixed — it moves with your own hourly cost and how aggressively you chase. Run the numbers for your business using the job profitability calculator, because a small unpaid invoice chased hard can quietly turn a profitable job into a loss once your time is counted properly.

Put it in writing once, then leave it alone

The goal isn't to punish slow payers — most late payments are logistics, not malice. The goal is a fee structure that's big enough to notice, written down before the job starts, and applied the same way every time, so you're not negotiating penalties invoice by invoice. If you don't already have standard terms covering this, it's worth setting up once as part of a wider operations kit alongside deposits, cancellations and scope-change clauses, so late fees are just one line in a system rather than an argument you have every month.