Charging Interest on Overdue Invoices: What Actually Sticks in Canada

Your invoice says “1.5% interest charged on overdue accounts.” Has any client of yours ever actually paid it?

Most small business owners print that line and never test it. Here’s what’s really going on with charging interest on overdue invoices in Canada, question by question.

Do you have to say so before you can charge it?

Yes, essentially. Interest on a late payment isn’t something you’re automatically entitled to add after the fact — it has to have been part of what the client agreed to when they accepted the work. That usually means it was in your written quote, contract, or on the invoice terms the client saw before the balance became overdue. Adding an interest line to a follow-up email six weeks after the due date, with no earlier mention of it, is the kind of thing that won’t survive a serious challenge.

What rate can you actually put on it?

There’s no single number every Canadian business is entitled to charge, and no flat percentage worth memorizing — the right way to set the figure is to check current commercial norms and legal limits with a bookkeeper or business lawyer before you finalize your terms, rather than copying a rate off a template you found online. If you’re used to a prescribed statutory rate applying automatically the way some systems work at home, that’s the adjustment: Canadian commercial interest is a contract term you set, not a number the law hands you.

Is a flat late fee different from interest?

Functionally, yes. A flat late fee (say, a fixed dollar amount added once a payment passes a certain age) is structured differently from a compounding interest rate, and the two get treated differently by anyone assessing whether the charge is fair and enforceable. Mixing the language — calling a flat fee “interest” or vice versa on your invoice — creates ambiguity that works against you if a client ever disputes it. So is a late payment fee enforceable in Canada? On the same basis as interest: only if the client agreed to it before the balance went overdue.

Can you charge interest with no written contract at all?

Much harder. Verbal agreements aren’t nothing in Canadian contract law, but proving what was actually agreed on an interest rate, after the fact, with no paper trail, is a weak position to argue from. If you’re working on handshake terms with a new Canadian client — something that may feel normal if that’s how business got done where you’re from — put the payment terms in writing before the first invoice goes out, even if it’s just a line in a confirmation email.

Is there a rate so high it stops being enforceable?

Setting a rate meaningfully above what’s commercially normal is worth checking with a lawyer before you commit to it in writing — very high rates can cross into territory Canadian law treats seriously, and that’s not a line to guess at. This is one of the few places where getting professional advice before you print the invoice terms costs far less than finding out afterward.

Does anyone actually pay it?

Rarely, in practice. Most small business owners who’ve chased overdue accounts will tell you the interest line does more work as a deterrent and a negotiating chip than as money that actually lands in the account. The invoice terms matter more for the conversation they let you have than for the cheque they eventually produce.

Before you finalize interest terms on your own invoices, get a business lawyer or accountant to check the wording — it’s a short conversation now, against a much longer one if a client disputes it later. Cape2Canada’s guides are built around the immigration side of the move; for the fine print on collecting what you’re owed, that’s a Canadian professional’s job.