Step 1 — Confirm it is actually overdue
Before sending anything, confirm the invoice was issued correctly: right address, right amount, right due date, sent to the right contact. About one in ten 'overdue' invoices turns out to have been sent to a stale email or stuck in a spam filter. A 30-second check prevents you from chasing an invoice the buyer never received.
Step 2 — Send the friendly reminder (day +1 to +3)
A short, warm message that re-attaches the invoice and asks if there is anything to clarify. Most invoices clear in this window. This is also when you find out about hidden blockers — a missing PO number, a procurement form, or a vacationing approver.
Step 3 — Personal follow-up (day +7 to +10)
If the friendly reminder produced silence, switch from automated to personal. A short note from a real person — ideally the person who did the work — gets a much higher response rate than another templated email. Ask for a specific date the buyer expects to pay, not just a general acknowledgement.
Step 4 — Firm reminder with consequences (day +14 to +21)
Now the message gets structural: amount owed, original due date, days overdue, late-fee policy if disclosed, and a clear request for a confirmed payment date. Pause any new work for the same customer until the overdue invoice is resolved. Continuing to deliver into a non-paying customer is the single most common way small businesses end up with five-figure write-offs.
Step 5 — Final notice and escalation (day +30+)
The final notice names the deadline and the next step. After the deadline passes, your options depend on the size of the invoice and the relationship: a debt collection agency for mid-sized B2B invoices, small-claims court for documented contractual amounts, or a write-off for very small consumer invoices where recovery costs more than the invoice.
Whichever route you take, keep a clean paper trail of every reminder sent and every response received. Documentation is what turns a frustrating non-payment into a recoverable claim.
A worked example
Consider a £3,200 invoice issued 1 March, due 15 March. On 17 March (day +2), an automated reminder goes out — no response. On 22 March (day +7), a personal follow-up from the project lead — buyer replies that procurement needs a PO number. PO is added on 24 March; payment clears 1 April. Total owner time: 12 minutes. No relationship damage. That is what a working sequence looks like.