GST and invoicing in Australia (2026): BAS, invoices, Peppol

Australia's goods and services tax (GST) is a 10% tax on most goods, services and other items sold or consumed in Australia. It is collected by the Australian Taxation Office (ATO) under the A New Tax System (Goods and Services Tax) Act 1999, and businesses report it on their business activity statement (BAS). This guide covers what a small business needs in 2026: when to register, what to charge, when the BAS is due, what a valid tax invoice looks like and what is happening with Peppol eInvoicing.

GST in Australia at a glance

GST-free sales carry no GST, but you can still claim GST credits on the purchases you use to make them. The main GST-free items are most basic food, some education courses and course materials, some medical, health and care services and products, some childcare, water, sewerage and drainage, international transport, exports, and the sale of a business as a going concern. Exported goods are GST-free if they leave Australia within 60 days of the first payment or the invoice.

Input-taxed sales also carry no GST, but you cannot claim GST credits for the purchases used to make them. The most common are financial supplies, such as lending money, and selling or renting out residential premises.

Who must register for GST

You must register for GST:

• when your GST turnover (gross business income, not profit, minus GST) is $75,000 or more
• when you start a business and expect to reach $75,000 in the first year
• if your non-profit organisation's GST turnover is $150,000 or more
• if you provide taxi or limousine travel, including ride-sourcing, whatever your turnover
• if you want to claim fuel tax credits

You need an ABN before you register, and you must register within 21 days of becoming required to. Check your turnover every month: the ATO can backdate your registration by up to four years, and you may then owe GST on past sales even though you did not charge it. Registering voluntarily is possible below the threshold, but you generally have to stay registered for at least 12 months.

BAS: reporting and paying GST

If you lodge your quarterly BAS online, or through a registered tax or BAS agent, you may get extra time; this does not apply to the October to December quarter, whose 28 February date already includes a one-month extension. When a due date falls on a weekend or public holiday, you have until the next business day.

Cash or accruals. Businesses with an aggregated turnover under $10 million can account for GST on a cash basis, reporting GST when they receive or make payments. Most larger businesses must use the non-cash (accruals) basis.

Paying late. Unpaid BAS amounts attract the general interest charge (GIC). If you owe $200,000 or less, you may be able to set up a payment plan in ATO online services; contact the ATO before the due date if you cannot pay.

Tax invoices: what the law requires

You must give a customer a tax invoice within 28 days if they ask for one, unless the sale is $82.50 or less including GST. Your customers, in turn, need a tax invoice to claim GST credits on purchases above that amount.

For sales under $1,000, a tax invoice must include enough information to clearly determine these seven details:

1. 1That the document is intended to be a tax invoice
2. 2The seller's identity
3. 3The seller's ABN
4. 4The date the invoice was issued
5. 5A brief description of the items sold, including the quantity (if applicable) and the price
6. 6The GST amount (if any), shown separately or, when GST is exactly one-eleventh of the total, with the statement “Total price includes GST”
7. 7The extent to which each sale on the invoice is a taxable sale

For sales of $1,000 or more, the invoice must also show the buyer's identity or ABN. Many businesses use this fuller format for every invoice.

Other rules worth knowing:

• Mixed invoices: when an invoice includes both taxable and GST-free or input-taxed items, it must show which items are taxable, the GST payable and the total.
• Digital invoices are fine: a PDF sent by email is a valid tax invoice if it contains all the required information.
• Rounding: round GST to the nearest cent (0.5 cents rounds up), either on the invoice total or line by line under the ATO's rules.
• Recipient-created tax invoices (RCTIs): the buyer may issue the tax invoice instead of you only if you are both registered for GST, you agree in writing and the ATO allows RCTIs for that type of supply.
• Numbering: an invoice number is not one of the seven required details, but unique, sequential numbers make it far easier to match payments, credits and adjustment notes.

Corrections: adjustment notes

If a sale is cancelled, the price changes or goods are returned after you have reported the GST, you make an adjustment on your BAS. To make a decreasing adjustment, you generally need to give your customer a valid adjustment note (often called a credit note), unless the GST adjustment is $75 or less. The ATO's ruling GSTR 2013/2 sets out what an adjustment note must contain.

How long to keep records

Keep most business records, including tax invoices and adjustment notes, for five years from when you prepared or obtained them, or completed the transactions, whichever is later.

Peppol eInvoicing in Australia

Australia has adopted Peppol as its standard for eInvoicing: invoices travel as structured data directly from the supplier's software to the buyer's software, through accredited service providers on the Peppol network. The ATO is the Australian Peppol Authority, but it cannot see your invoices: eInvoicing in Australia is not a compliance or revenue measure. More than 400,000 Australian businesses are on the network.

The ATO accepts a Peppol eInvoice issued under the A-NZ Invoice Specification as a tax invoice even if it does not carry the words “tax invoice”, provided it contains all the mandatory data.

Between businesses, eInvoicing is voluntary. There is no mandate for private businesses to send or receive eInvoices.

Government is moving to eInvoicing by default:

If you supply government, or a large customer asks you to send Peppol eInvoices, you will need Peppol-enabled software or a Peppol access point provider for that part.

A worked example in Australian dollars

You run a small marketing agency registered for GST, reporting quarterly. From July to September you invoice clients $50,000 plus 10% GST.

1. 1GST on sales: $50,000 × 10% = $5,000; your clients pay $55,000.
2. 2GST credits: you buy a laptop for $3,300 including $300 GST and pay a subcontractor $11,000 including $1,000 GST, with valid tax invoices. GST credits = $300 + $1,000 = $1,300.
3. 3Net GST: $5,000 − $1,300 = $3,700, due with your BAS by 28 October.

To find the GST in a GST-inclusive price, divide by 11: $1,100 ÷ 11 = $100 GST, so the price before GST is $1,000.

Common GST mistakes in Australia

1. 1Crossing $75,000 without noticing. Check your GST turnover every month and register within 21 days.
2. 2Leaving out the buyer's identity or ABN on invoices of $1,000 or more.
3. 3Claiming GST credits without a tax invoice for purchases over $82.50.
4. 4Charging GST on GST-free sales, such as basic food or exports, or claiming credits for input-taxed sales such as residential rent.
5. 5Reducing GST without an adjustment note when the adjustment is above $75.
6. 6Assuming the online extension applies to every quarter. The 28 February date for the December quarter does not move.
7. 7Sending a PDF when a government customer expects a Peppol eInvoice.

How Clientlly helps

Clientlly takes care of the invoicing and records behind your BAS:

• Sequential invoice numbering per series, with the 10% rate and GST-free lines on every invoice.
• Credit notes linked to the original invoice, so adjustments are easy to trace.
• Sales and purchase GST books per rate, including exports, and GST reports for you and your accountant or BAS agent, with Excel and PDF exports.
• Receipt scanning that reads the GST automatically, so your credits are backed by the documents.
• Multiple currencies, invoice PDFs in your client's language, a card payment link on the invoice and a record of when each invoice was opened.
• Automatic reminders 3, 14 and 30 days after the due date, recurring invoices for retainers, and a mobile app. See our guide to getting paid faster.

Clientlly is not a Peppol access point; if a customer requires Peppol eInvoices, you will need a Peppol-enabled provider for that part. See the invoicing features, the accounting module and how to move your data across.