GST for tradies: a plain-English guide

General information, not tax advice

This guide explains how GST works for a typical small trade business, using the ATO’s own pages, linked at the end. Tax depends on your circumstances. Before you act on anything here, check it with your accountant or BAS agent, or with the ATO.

Do you have to register?

You must register for GST when your GST turnover reaches A$75,000. The ATO tests it two ways, and either one counts:

• Current turnover: this month plus the previous 11 months.
• Projected turnover: this month plus the next 11 months.

GST turnover is your sales excluding GST, not your profit. A sole trader who invoices A$6,500 a month is at A$78,000 a year and must register, even if materials and fuel take half of it. Non-profits register at A$150,000. You need an ABN to register.

Register within 21 days of reaching the threshold. The ATO says if you should have registered and did not, you may have to pay GST on your sales since the date you were required to register, even though you never charged it, plus penalties and interest. In practice that is one eleventh of those sales, out of your own pocket.

You can also register voluntarily below the threshold. Then you must charge GST and lodge a BAS like any other registered business, and you can claim GST credits on what you buy.

How to work out GST

GST is 10% of the price before GST. To find the GST inside a price that already includes it, divide by 11.

A common mistake is taking 10% off a GST-inclusive price. On a A$1,320 job that gives A$132, which is A$12 too much.

Quote and price with GST included

When you show prices to consumers, the ACCC says the price must be a single total that includes GST and any unavoidable fees. A homeowner reading “A$1,200 + GST” in small print can be misled, and the ACCC has warned service businesses about exactly this.

Prices quoted only to other businesses do not have to include GST, but the ACCC calls GST-inclusive pricing best practice. Many trades quote everyone GST-inclusive and show the GST amount underneath, which suits both. Our guide to quotes and estimates covers what else a quote needs.

Sales without GST

Not every sale carries GST. Some are GST-free and some are input-taxed. If a tax invoice mixes taxable and GST-free lines, it must show how much of each item is taxable.

If you are not sure whether something you sell is taxable, check with the ATO or your accountant before leaving the GST off. Getting it wrong means either overcharging your customer or paying the GST yourself later.

Tax invoices, briefly

Once registered, title your invoices “Tax invoice” and show your ABN, the date, what you sold, and the GST. For sales of A$1,000 or more, add the buyer’s name or ABN. If a customer asks for a tax invoice for a sale over A$82.50, you have 28 days to give one. Before you register, call it an “Invoice” and do not add GST. The full list, with ATO sources, is in our tax invoice requirements guide.

Cash or accruals: when the GST is due

Businesses with aggregated turnover under A$10 million can choose how they account for GST:

• Cash basis. You report GST in the period the customer pays you, and claim credits in the period you pay your suppliers.
• Accruals basis. You report GST in the period you issue the invoice or receive any payment, whichever comes first, and you report the full GST even if you have only been part paid.

On accruals, an invoice the customer has not paid still costs you its GST at BAS time. If late payers are common in your business, that is worth talking through with your accountant, and it is one more reason to chase overdue invoices.

Your BAS: the three GST boxes

Businesses with GST turnover under A$10 million use Simpler BAS, and report three GST figures:

• G1 Total sales. All your sales, including GST-free ones. You choose whether to report including or excluding GST, and tick the box to say which.
• 1A GST on sales. The GST you collected.
• 1B GST on purchases. The GST credits you can claim on business costs.

You pay the ATO 1A minus 1B, or get a refund if 1B is larger. Whole dollars only.

A worked example. In a quarter you invoice A$33,000 including GST, all taxable. G1 is A$33,000 (reported including GST) and 1A is A$3,000. You bought materials, fuel and tools with A$800 of GST in them, so 1B is A$800. You pay A$2,200. Your BAS may also include PAYG withholding if you have employees, and PAYG instalments; those are separate from GST.

When your BAS is due

Businesses with GST turnover under A$20 million generally lodge quarterly. The ATO’s quarterly due dates are:

As at 30 October 2026, the July to September BAS was due on 28 October, and the next one is due 28 February 2027. Lodging online can give you extra time, and registered tax and BAS agents may have more. Businesses registered voluntarily below A$75,000 can choose to report GST annually.

Paying subcontractors: TPAR and ABNs

If your business pays contractors for building and construction, cleaning, and some other services, the ATO requires a taxable payments annual report (TPAR) by 28 August each year, listing what you paid them. Wages and materials-only payments are not included. Keep each subbie’s ABN, name and address on file through the year so August is not a scramble.

If a supplier does not quote an ABN and no exception applies, you generally must withhold 47% of the payment and send it to the ATO. The same applies in reverse: always put your ABN on your own invoices.

Keep records for five years

Keep sales and purchase invoices, adjustment notes and your GST workings for five years. Digital copies are fine. A receipt photo stored against the job is far easier to find at BAS time than a shoebox.

A habit that makes BAS time easier

GST is the ATO’s money passing through your account. A simple habit many tradies use is to move one eleventh of every payment into a separate account the day it arrives. When the BAS is due, the money is already there. This is a common practice, not a rule, and your accountant may suggest a different approach.

How Karya Falak helps with GST

• Prices are entered including GST by default, and each line can be GST, GST-free or input-taxed.
• Invoices are titled “Tax invoice” only when your business is registered for GST.
• The GST on sales report gives your G1 and 1A figures on a cash or accruals basis, with a CSV export.
• GST credits (1B) stay with Xero, QuickBooks or your bookkeeper, where your purchases are recorded. Issued invoices and payments sync to either.
• Job costing keeps receipts with each job, for your own figures.

Sources and date checked

Rules checked 30 October 2026 against ato.gov.au, business.gov.au, ACCC and state regulator guidance. General information only, not tax or legal advice. Thresholds, due dates and rates can change, so confirm the figures for your business with your accountant, your BAS agent or the ATO before you lodge.