Resource
How to chase overdue invoices: a schedule and wording
Most overdue invoices are paid after a clear, well-timed reminder. The ones that are not usually have a reason: wrong contact, missing PO number, a dispute, or a cash problem on the customer’s side. A fixed schedule surfaces the reason early. This guide gives a schedule, sample wording that stays firm but courteous, and the points where a person decides.
Written by Kyn Technology Pte Ltd (UEN 202622080C), which builds invoice chasing systems. Adjust the days to your payment terms. This is practical guidance, not legal advice.
Schedule at a glance
| When | Message | Tone | Sent by |
|---|---|---|---|
| 3 days before due | Courtesy note | Friendly | Accounts |
| 1–3 days overdue | First reminder | Polite | Accounts |
| 7–14 days overdue | Second reminder and call | Firm | Accounts, copy to account owner |
| 21–30 days overdue | Third reminder | Formal | Owner or finance lead |
| After third | Owner decides next step | — | Owner |
Nine steps
1. Set terms before the work starts
Collections start at the quote. State payment terms, deposit, due dates, payment methods and the contact for accounts on the quote and the invoice. A customer cannot be held to terms they never saw. Ask the customer who handles payment on their side, and get that person’s email.
2. Send the invoice correctly
Send each invoice to the accounts contact, with the PO number if the customer issued one, the due date in the first line, and bank details or a payment link. Many late payments are invoices sitting with the wrong person or missing a PO number the customer’s finance team needs.
3. Courtesy reminder: 3 days before the due date
A short note that the invoice falls due soon. No pressure, no request for a reply. Its job is to surface problems early: wrong contact, missing PO, a dispute nobody mentioned.
4. First reminder: 1 to 3 days overdue
Polite and factual. State the invoice number, amount and due date, attach the invoice again, and ask them to confirm a payment date. Assume an oversight.
5. Second reminder: 7 to 14 days overdue
Firmer. Restate the amount and how many days overdue it is, reference the first reminder, and ask for a payment date by a specific day. Copy the person who signed the quote. Follow up with a phone call.
6. Third reminder: 21 to 30 days overdue
Formal. State the next step you will take and when: pausing further work, holding delivery, or referring the matter on. Only state a consequence you will carry out. The business owner or finance lead should approve this message.
7. Record every promise to pay
When a customer replies with a date, record it and stop the sequence until that date. If the date passes without payment, resume at the next stage and mention the missed promise. A promise that is not recorded is forgotten.
8. Stop on a dispute
If the customer disputes the invoice, stop reminders on that invoice and hand the thread to the account owner. Reminding a customer about an invoice they have disputed damages the relationship and rarely gets it paid.
9. Escalate beyond reminders
After the third reminder, the decision belongs to the owner: a payment plan, a stop on new work, a formal letter of demand, or a claim. In Singapore, small claims may go through the Small Claims Tribunals, subject to its limits and rules. Take legal advice before formal steps.
Sample wording
Courtesy note
Subject: Invoice INV-1042 due 15 October. Dear Ms Tan, a reminder that invoice INV-1042 for SGD 4,800.00 falls due on 15 October. A copy is attached, with our bank details. Please let us know if anything is needed to process it. Thank you.
First reminder
Subject: Invoice INV-1042 now overdue. Dear Ms Tan, invoice INV-1042 for SGD 4,800.00 was due on 15 October and remains unpaid in our records. If payment has been made, please send the remittance advice and we will update our records. Otherwise, could you confirm when we can expect payment? The invoice is attached. Thank you.
Second reminder
Subject: Second reminder, invoice INV-1042, 10 days overdue. Dear Ms Tan, we wrote on 16 October about invoice INV-1042 for SGD 4,800.00, now 10 days overdue. Please confirm a payment date by 28 October. If there is a problem with the invoice, please tell us so we can resolve it. I will call you on Thursday to follow up. Regards.
Third reminder
Subject: Final reminder, invoice INV-1042, 25 days overdue. Dear Mr Lim, invoice INV-1042 for SGD 4,800.00 is 25 days overdue despite reminders on 16 and 25 October. Unless payment is received by 14 November, we will pause work on your account until it is settled. We would prefer to resolve this directly. Please contact me to agree a payment date. Regards.
Names, amounts and dates above are illustrative.
Tracking
A reminder schedule only works if each invoice’s state is visible. Track, per invoice:
- Due date, days overdue and amount outstanding.
- Deposit and balance separately, where jobs are billed in stages.
- Last reminder sent, and the next one due.
- Promise-to-pay date, if any.
- Dispute status.
- Customer history: how many invoices paid late in the last 12 months.
What to automate
The tracking, the dates and the drafting are mechanical. The sending decision, disputes and escalation are not. A system KYN built for an events studio uses this split: the system reads the mailbox for payments and promises, tracks deposits and balances, flags late payers, and drafts first, second and third reminders. A person sends each one.
See invoice chasing and collections automation for how it is built, bank reconciliation for confirming payments against the bank, and /pricing for fees.
Frequently asked questions
How soon should I send the first reminder?
Within 1 to 3 days of the due date. A courtesy note 3 days before the due date catches wrong contacts and missing PO numbers before the invoice is late.
Should reminders go by email or WhatsApp?
Email is the default for invoices, because it carries the attachment and reaches the accounts team. WhatsApp can work for smaller customers who have agreed to be contacted that way, sent from the official WhatsApp Business Platform.
Can I charge interest on late payments?
Only where your contract or terms allow it. Take legal advice on the wording before relying on it.
What if the customer says they have already paid?
Ask for the remittance advice, then check it against the bank statement. Pause reminders on that invoice until it is confirmed.
When should I stop work for a customer who has not paid?
That is a business decision, made by the owner. State it in the third reminder only if you will carry it out, and check your contract first.
Should reminders be sent automatically?
The courtesy note and first reminder can be, if you are comfortable with that. Firmer reminders should be reviewed by a person, because they often need context the system does not have.