The documents in order
| Document | When | What it does | Legal weight |
|---|---|---|---|
| Estimate | Before the work | Approximate price; may change | Not a fixed offer |
| Quote | Before the work | Fixed price for a defined scope, valid until a date | An offer; once accepted, part of the contract |
| Invoice | After the work, or at agreed stages | Requests payment for what was supplied | Records the sale and the amount owed |
| Tax invoice | As for an invoice, from a GST-registered business | As above, plus the details the buyer needs to claim GST credits | Must meet the ATO's requirements |
| Receipt | After payment | Confirms payment was received | Proof of transaction for the customer |
What a quote is for
A quote fixes the price and the scope before anyone commits. It protects the customer from a surprise bill and protects you from scope creep: anything not in the quote is a variation, priced separately. A good quote names the work line by line, states what is excluded, shows GST if you are registered, and carries an "Accept by" date after which it lapses.
Legally, a quote is an offer. When the customer accepts it (in writing is best, even a reply email), it usually becomes part of the contract between you. That is why vague quotes cause disputes. If you cannot fix a price, send an estimate instead, say so clearly, and say what would change the figure. Under the Australian Consumer Law, calling an estimate a quote and then charging more can be misleading.
What an invoice is for
An invoice records a sale and asks for payment. It should describe what was actually supplied, which may differ from the quote if there were variations; list those as separate lines and reference the quote number so the customer can match them.
If you are registered for GST, the invoice is a tax invoice and must contain the ATO's required details: it must be clear it is intended as a tax invoice, show your identity and ABN, the date, a description of each item with quantity and price, the GST (or the statement that the total includes GST), which items are taxable, and from $1,000 the buyer's identity or ABN. You must provide one within 28 days if asked, unless the sale is $82.5 or less. A quote cannot do this job, because a quote is not a sale.
Turning a quote into an invoice
Because the scope and lines are already in the quote, the invoice should start from it. In the quote generator, open an accepted quote and click "Convert to invoice". The client, lines, GST settings and payment details are copied into a new tax invoice with today's date and the next invoice number; the quote stays in your history as the record of what was agreed. Edit lines for variations before you download.
For staged jobs, invoice the deposit and each progress payment separately. Each is a tax invoice for the amount it bills, with its own GST.
Where receipts fit
A receipt confirms the customer paid. It matters most for cash payments and for customers who need proof for a claim or reimbursement. If you are GST-registered and the receipt includes every tax-invoice detail, it doubles as a tax invoice. The receipt generator can create one from a paid invoice in a click.
Numbering
Keep separate sequences for each document type (Q-1001, INV-1001, R-1001). It avoids confusion when a customer refers to "number 1004", and it keeps your invoice numbers unbroken, which bookkeepers and auditors like. The generator keeps the three sequences for you and lets you set the prefixes and next numbers.