Quick answer
A quote is an offer you send before work begins, stating the price and scope you’re proposing. An invoice is a request for payment you send after (or as) you deliver the work. A quote is not a tax invoice and can’t be used to claim GST credits; only the invoice does that. Once a client accepts a quote, it becomes a binding agreement on price — so quote carefully.
Quote vs invoice: the core differences
| Quote | Invoice | |
|---|---|---|
| Timing | Before the work | During or after the work |
| Purpose | Offer a price to win the job | Request payment for the job |
| Creates a debt? | No | Yes |
| GST credit for client? | No | Yes (if a valid tax invoice) |
| Has a due date? | Has an expiry date | Has a payment due date |
| Unique number? | Quote number (optional) | Required invoice number |
What about an estimate?
An estimate sits before a quote. It’s a rough, non-binding indication of likely cost — useful when you can’t pin down the exact scope yet (“probably $2,000–$2,500 depending on what we find”). A quote, by contrast, is a firm price. Label which one you’re sending so the client knows whether the number can move.
When to send a quote
- The client asked “how much?” before committing
- The job is large enough that price certainty matters to both sides
- You want to lock in scope so extra work can be billed as a variation
Always put an expiry date on a quote (“valid for 30 days”). Material and labour costs move, and an open-ended quote can come back to bite you months later.
When to send an invoice
- The work is done (or a milestone/deposit is due)
- You need to actually get paid — an invoice creates the debt
- The client needs a tax invoice to claim a GST credit
Unlike a quote, an invoice must carry a unique invoice number and, if you’re GST-registered, be labelled a “Tax Invoice”. See what must be on a tax invoice for the full field list.
How a quote becomes an invoice
When the client accepts and the work is underway or done, you turn the quote into an invoice. The smart way is to reuse the exact same line items and totals so the numbers always match the agreement — then add an invoice number, an issue date, and a payment due date. A client who sees an invoice total that differs from the accepted quote will query it, and that’s a delay you don’t want.
Free Invoice App keeps your line items, client details, and GST settings in one place, so producing the matching invoice is fast and consistent. Get started free or see pricing.
Frequently asked questions
Is a quote legally binding in Australia?
Once accepted, a quote generally binds you to the price and scope stated — so be precise and add an expiry date. An estimate is different: a rough, non-binding indication of cost.
Is a quote a tax invoice?
No. A quote is an offer before the work; a tax invoice is the payment request after, and it’s the document the ATO recognises for GST. A client can’t claim a GST credit from a quote.
Do I charge GST on a quote?
If you’re GST-registered, show GST so the client sees the true total, and state whether prices are GST-inclusive or exclusive. The GST only becomes payable when you issue the tax invoice.
How do I turn a quote into an invoice?
Reuse the accepted quote’s line items and totals, add an invoice number and due date, label it “Tax Invoice” if registered, and send it. Good tools convert a quote to an invoice in one click so the figures match.