Put the fee on the invoice, not only in a chase email
Clients should see late-fee policy on the invoice PDF (or the signed agreement) before work starts or before the due date—not as a surprise in an overdue thread. A short note under payment terms works: what triggers the fee, how it is calculated, and that the pay-now balance will reflect any applied fee on a revised invoice. If the fee was never disclosed, skip it and use a clear status request instead.
Sample clause language you can adapt
Invoice note example: “Payment is due by the due date on this invoice. Balances unpaid more than 7 days after the due date may incur a late fee of X% of the overdue balance (or $Y, whichever is greater), applied once per overdue invoice.” Email disclosure example: “As noted on invoice INV-1042, a late fee may apply after [date]. Pay the current balance here: [pay-now link].” Keep numbers consistent across PDF, email, and any revised invoice so the client is not comparing two different totals.
When not to charge a late fee
Skip fees when scope is disputed, the invoice was late or incomplete, this is a first slip with a long-term client, or local rules make the clause risky. Fees also land poorly on small consumer jobs versus clear B2B terms. In those cases, send a polite overdue status ask with the original PDF and pay-now link, then decide whether a revised invoice with an updated balance is worth the relationship cost.
Clear terms beat surprise fees
Start free, put payment terms on a professional invoice with a pay-now link, and follow up on the same record when a balance is late.
Start for free