For Australian small businesses and sole traders with overdue invoices

Work out the interest owed and send a firm letter.

Upload the overdue invoice and your terms. Get an interest calculation and a polite, firm payment demand.

Upload the unpaid invoice and the contract or terms that set an interest rate on late payments. You get the interest worked out day by day and a payment demand letter you can edit and send.

Pre-order

Pre-orders open now. First deliveries from November 2026. Full refund if we can't deliver by the agreed date.

How it works

  1. 01

    Upload the invoice and terms

    Add the overdue invoice, the payment terms or contract, and any payments or messages since the due date.

  2. 02

    We calculate and draft

    We work out interest from the due date using the rate in your terms, show the working, and draft a firm, polite demand with a clear deadline to pay.

  3. 03

    You check and send

    You check the numbers and the tone, add anything we missed, and send it yourself.

Many small businesses don't chase late invoices because the letter feels awkward and the maths is fiddly. We do both, using only the rate you actually agreed with the customer. If there's no agreed rate, we say so rather than make one up.

Pricing

Letter + calculation

A$49 inc. GST

  • Interest calculation using your contract rate, with the working shown
  • One payment demand letter for you to edit
  • Covers part payments made since the due date
  • Delivered within 2 business days
Pre-order — Letter + calculation

Follow-up sequence

Recommended

A$149 inc. GST

  • Everything in Letter + calculation
  • A friendly reminder, a firm demand and a final notice, timed for you
  • Interest updated at each step
  • A short summary of the debt for your accountant or lawyer
  • Delivered within 2 business days
Pre-order — Follow-up sequence

Pre-order

No payment now. We’ll email you before anything is charged.

We use your email for this pre-order and, if you opt in, product updates. To be removed, email privacy@lynxbay.au.

FAQ

Is this legal or financial advice?

No. We do the arithmetic from your terms and draft a letter in your name. We're not a law firm or a debt collector. If the customer disputes the debt, or you're thinking about court or a tribunal, get legal advice.

What if my terms don't mention interest?

Then there may be no agreed rate to claim. In NSW, Legal Aid NSW says that without an agreement about interest you can use the pre-judgment interest rate under the court rules, which the Local Court publishes. Other states and courts have their own rules, so we won't add statutory interest to a letter. We'll point you to where to check.

Will the letter make them pay?

We can't promise that. A clear, polite letter with the numbers set out is a reasonable first step, and it also gives you a record that you asked.

Is the letter AI-generated?

It's AI-assisted. It's a draft for you to check and send.

What happens to my invoices?

We use them only to deliver your order. We delete them 30 days after delivery and never use them to train AI models.

Lynx Bay Pty Ltd doesn't give legal or financial advice and isn't a law firm or debt collection agency. We don't verify, certify or guarantee that any amount is legally owed or will be paid, and we're not connected to any court, tribunal or government body. Calculations and letters are drafts for you to check.