What actually makes an invoice a "tax invoice"
A tax invoice isn't just an invoice with a bigger name. It's a specific document the Australian Taxation Office defines, and only a business registered for GST can issue one. If you're not registered, the correct document is a plain invoice, with no GST added and no GST amount shown, because there's nothing to claim. If you are registered, a tax invoice has to identify itself as one, show your identity and ABN, the date, a description of what was sold, and the GST-inclusive total, with the GST amount either shown separately or stated as included in the price. Miss one of those and, strictly, what you've handed over isn't a valid tax invoice, which matters more to your customer than to you, because they need a valid one to claim their own GST credit.
The rule that catches people out
Below a GST-inclusive total of $1,000, a tax invoice can skip the buyer's details entirely. Just your information and the sale is enough. At $1,000 or more, the buyer's identity has to be on it: their name, business name, address or ABN, any one of those is sufficient. It's an easy rule to forget on a single large job, because most of the invoices a trade business raises in a week sit well under that mark, and then a whole bathroom renovation or fit-out comes through at $4,000 and the ordinary template is missing a field. This generator flags it automatically once your total crosses the line, but the underlying rule is worth knowing rather than just trusting a tool to catch. See the ATO's own page on tax invoices for the complete list of what has to be on one.
Why your ABN has to be on there
An ABN on an invoice does more than fill a line. It tells the person paying you that you're a legitimate business, not someone working under the table, and it lets a GST-registered customer claim the credit they're entitled to. Leave it off, or quote it wrong, and you've handed them a document that can't do either job.
There's a sharper consequence too. If you supply goods or services in the course of running a business and you don't quote an ABN, the business paying you can be required to withhold tax from the payment at the top rate, rather than paying the invoice in full and leaving you to sort the tax out at year's end. The ATO's own guidance on registering for GST covers when an ABN needs to be quoted and to whom, and most bookkeepers will tell you the same thing from experience: a missing ABN is the fastest way to turn a straightforward payment into a phone call neither side wanted to make.
Ex-GST or inclusive. Pick one and say so
Every line item here is treated as the ex-GST price, because that's the number a business actually controls. GST gets added on top, automatically, at whatever rate applies. The alternative, entering GST-inclusive prices and backing the tax out, works mathematically but invites the exact confusion covered on our GST calculator: a customer who was quoted "$500" assuming that's the final figure, when you meant $500 before tax. Stating ex-GST consistently, on quotes as well as invoices, removes the ambiguity before it becomes an argument about who owes what.
What happens after you send it
Once an invoice goes out, it isn't done. It's a record you're required to keep. The ATO's rules on record keeping for business generally require five years' retention from when the transaction was completed, longer for depreciating assets and multi-year claims. That's not a suggestion: a missing tax invoice is the difference between a GST credit you can substantiate and one the ATO can disallow on review. A PDF saved the day you sent it, filed by date or customer, does the job. You don't need accounting software to be compliant, you need a folder you'll actually be able to find in three years.
Quote, estimate or variation: not the same word
Before an invoice gets written, three earlier documents shape what ends up on it, and tradies use the words loosely. A quote is meant to be a firm figure. Give a customer a quote and, in most circumstances, that's the price the job is done for, not an opening bid for renegotiation once the walls are open. An estimate is deliberately different: a rough figure, offered honestly as rough, with no promise attached to it. Consumer Affairs Victoria's guidance on giving quotes for tradespeople and small works is blunt about it: put the figure in writing, and agree upfront how you'll handle any changes to the price or timeframe once work starts, rather than discovering the gap for the first time when the invoice lands.
A variation is what happens when the job changes after the quote was accepted, an extra power point, a different tile, ground that turned out to be rock instead of soil. None of that belongs folded quietly into the final invoice as if it was there from the start. A variation should be its own short document, what changed, why, and the new figure, agreed before the extra work happens rather than after. An invoice that jumps from the quoted total to a bigger number with no paper trail in between is the fastest way to turn a happy customer into a dispute, even when every extra dollar was completely reasonable.
Recipient-created tax invoices: when the other side writes it
Everything above assumes you're the one issuing the invoice, and for almost every trade job, that's correct. There's one exception worth knowing about even if you'll never use it: a recipient-created tax invoice (RCTI), where the buyer, not the supplier, writes the tax invoice and the supplier accepts it instead of raising their own. The ATO only allows this for specific arrangements set out in its recipient-created tax invoices determination. Both parties have to be GST-registered, and there has to be a written agreement setting out how it will work before a single RCTI is issued.
Some larger builders and head contractors insist on RCTIs from their subcontractors, generating a self-billing invoice against completed work rather than waiting on the sub to send one. If a head contractor ever hands you an RCTI agreement to sign, read what you're actually agreeing to. You're trading the usual control over what your own invoice says for whatever their system produces, which makes it worth checking every RCTI they issue against what was actually done on site, not just trusting the total.
When a job changes after you've already invoiced
If GST was already charged on the original figure and the price changes afterwards, whether the job grew, shrank, or a discount landed later, the original invoice usually isn't reissued. What corrects it is an adjustment note: a short document recording the date, the reason for the change, and the dollar difference between the old price and the new one. It matters because your customer's GST credit is tied to the figure you originally told them, and if that number moves without a record explaining why, both sides' activity statements stop matching reality.
For most trade jobs this only comes up on the larger contracts, where a scope change happens after invoicing rather than before it. On a standard job, getting the variation agreed and priced before the invoice goes out avoids ever needing one at all.
Payment terms, and what to do when they slip
Every invoice this tool builds now carries a due date, worked out from the invoice date and whichever payment term you choose: on receipt, 7 days, 14 days or 30 days. There's no single standard here, whatever industry forums might tell you. What matters is that the term is on the invoice in writing, agreed with the customer before the job starts rather than announced for the first time when the bill arrives, and applied the same way to every job so nobody can claim they were treated differently.
Shorter terms get you paid sooner, which matters more to a sole trader carrying materials on a card than it does to a business sitting on cash reserves. Longer terms are sometimes unavoidable on commercial and government work, where the client sets the term rather than negotiating it. Whatever you choose, write it down. A payment term nobody agreed to is just a hope.
When a due date passes with nothing in the account, the first move is the boring one: a short, polite reminder, sent the day after, not two weeks later. Reference the invoice number, restate the amount and the due date, and ask when it'll be paid rather than accusing anyone of anything. Most late payments are genuinely just forgotten, not disputed. If a second reminder gets no response, a phone call usually moves things faster than a third email, and if it still goes nowhere, that's when a formal letter of demand, or for smaller amounts a state tribunal's small claims process, becomes worth considering rather than writing the job off.
"I never got your invoice"
It happens on almost every trade eventually. You sent the PDF, the customer swears it never arrived, and now you're chasing payment on something they claim they never saw. A few habits turn this into a five-minute fix instead of a stand-off. Send from an address you actually check, not a personal inbox that quietly filters business mail into spam. Keep a copy of every invoice filed by date or job, so it can be resent in thirty seconds rather than rebuilt from memory. And if it keeps happening with the same customer, ask for a one-line reply confirming receipt. That closes off the excuse for good.
A plasterer I know reckons he used to lose three or four invoices a month this way, not sent wrong, just never opened at the other end. Once he started BCC'ing himself on every invoice, that stopped completely. Small habit, real difference. And for the record, a digital copy is enough to satisfy the ATO's record-keeping rules. A printed folder isn't required, as long as what you keep is a true, clear copy you can reproduce if asked.
Using this generator properly
This tool builds a tax invoice (or a plain invoice, if you're not GST-registered) from the details you enter, and gives you a clean, printable version at the bottom of the page. Use your browser's print dialog and save as PDF rather than a screenshot, so the customer gets something that opens and prints properly at their end too. Nothing you type here is sent anywhere; the whole thing runs in your browser and the only record is the PDF you save. It remembers your business, payment and logo details in this browser between visits, never your customer's details and never the line items, and offers the next invoice number automatically once you've used one, so a sole trader invoicing every week isn't retyping the same ABN and BSB each time. What it won't do is tell you which of those invoices have actually been paid: that's bookkeeping, a different job to generating the invoice in the first place, and mixing the two up is how a business ends up chasing a customer who already paid, or missing one who never did. If your invoicing volume is more than the odd job, a proper quoting-and-invoicing system removes the manual entry entirely (numbering, GST handling and customer records all following on from the quote instead of being retyped for every job), which is the kind of admin our business systems work is built to take off your plate. And if the invoices you're sending don't match the site or Google listing a customer found you through, that mismatch costs trust before the job even starts, worth checking against our web design and pricing pages while you're at it.