An unpaid invoice reminder should feel like a clear nudge — not a confrontation. The goal is simple: remind them what's open, make it easy to pay or reply, and protect the relationship.
When to send a reminder for an unpaid invoice
- 1–3 days after due — friendly check-in ("did this land?")
- 7–14 days overdue — clearer unpaid invoice reminder with amount + due date
- After a broken promise — reference the date they gave you
- Long silence — firmer ask with a concrete next step or deadline
If they already disputed a line item or asked a question, answer that first. A blind reminder for an unpaid invoice on top of an open dispute feels tone-deaf.
A polite unpaid invoice reminder you can send
Subject: Reminder — invoice [INV-2041] ([amount]) Hi [Name], Quick reminder that invoice [INV-2041] for [amount] was due on [due date] and still shows as unpaid on my side. If payment is already in motion, great — ignore this. If anything's unclear on the invoice, reply and I'll sort it. Thanks, [Your name]
Three rules that keep reminders polite
- Assume competence, not bad faith. Most late payments are process, not spite.
- Put the facts up front. Number, amount, due date — then the ask.
- Offer an off-ramp. "If something's blocking payment, tell me" lowers defensiveness and often surfaces the real issue.
What not to do
- All-caps subject lines or "URGENT SECOND NOTICE" on the first overdue day
- CC'ing their boss before you've tried a normal reminder
- Threatening legal action in the first or second email
- Sending the same generic reminder forever with no tone change
A simple reminder cadence
Day 0: invoice. Day +due+2: friendly follow-up. Day +10: unpaid invoice reminder. Day +21: firmer note. After that, decide whether to escalate, pause work, or write it off — based on the relationship, not emotion in the moment.
Need copy-paste variants? See invoice follow-up email templates. If they promised a date and missed it, read what to do when they said "I'll pay Friday".