Your first BAS: a tradie's plain-English walkthrough

How to do your first BAS in Australia: the ATO sends you a BAS once you register for GST. You report the GST you collected on your invoices, subtract the GST you paid on purchases, and lodge online by the quarterly due date. It is shorter than it looks.

General information only. For your situation, check with the ATO or a registered BAS agent.

What is a BAS, in plain English?

A Business Activity Statement is the form you use to tell the ATO how much GST you collected, how much you are claiming back, and to pay the difference. Think of it this way: once you are registered for GST, you are the ATO's collection point. You add 10% on top of your invoices, hold it for a quarter, then hand it over, minus the GST you already paid out on your own tools and materials.

That is genuinely most of it. The ATO's BAS page covers the formal detail, but most sole tradies are on what the ATO calls Simpler BAS, which means you only report three numbers. The form is shorter than the dread suggests.

Why did I even get a BAS?

You got a BAS because you registered for GST, and the ATO sends one automatically to every GST-registered business. You must register for GST once your GST turnover reaches $75,000, within 21 days of crossing it. Turnover means total income, not profit. A lot of tradies miss that: if you invoiced $80,000 but only cleared $50,000 after costs, you are over the threshold.

If you registered voluntarily under the threshold, you still lodge. If you are reading this unsure whether you should be registered at all, start with our guide on whether you need to register for GST as a tradie, then come back. And if you are right at the start, your first ABN checklist covers the step before all of this.

What actually goes on it?

For most tradies on Simpler BAS, three numbers: G1, 1A and 1B. G1 is your total sales for the quarter, GST included. 1A is the GST you collected on those sales. 1B is the GST you paid on business purchases. Then 1A minus 1B is what you owe, or what the ATO refunds you if you spent big that quarter.

A worked example with round numbers:

• You invoiced $33,000 including GST this quarter. GST collected (1A) is $3,000.
• You spent $5,500 including GST on materials and a new nail gun. GST paid (1B) is $500.
• You owe the ATO $3,000 minus $500, which is $2,500.

If you pay wages there are also PAYG withholding labels, but a first-timer with no staff can ignore them. If you do have staff, that is a good moment to get a bookkeeper.

Where do the numbers come from?

The numbers come from your records: every invoice you sent is your GST collected, and every business receipt is your GST paid. This is the actual hard part of BAS, and nobody warns you. The first one we did meant a Sunday night adding up invoice GST line by line, and it is exactly as fun as it sounds.

If your invoices live in a shoebox or a dozen photo screenshots, BAS week is an archaeology dig. If they are tracked as you go, it is a five-minute job. Chippie tallies the GST on every invoice as you raise it, so the GST-collected side (your 1A) is already there when BAS time comes. You still need your purchase GST from receipts or your bookkeeper, but half the job is done. Getting your invoices right in the first place is what makes those figures reliable.

When is my BAS due?

Most small businesses lodge quarterly, and the due dates follow the same pattern every year:

Dates current for 2025-26, verified June 2026; they repeat each year but check the ATO page for your statement. Lodging online may give you an extra two weeks to lodge and pay a quarterly BAS, which matters when cash flow is tight. Paying is due when lodging is due, so plan for both together.

How to lodge your first BAS online

Lodging is a short online form, and you can review everything before you submit. The ATO's lodgement page lists all the channels, but for most people it goes:

1. Sole traders log in to ATO online services through myGov. Companies and partnerships use Online services for business.
2. Open the activity statement waiting in your account.
3. Enter G1, 1A and 1B (plus wage labels if you have staff).
4. Check the calculated amount matches what you expected.
5. Lodge, then pay by the due date using the payment options shown.

Had no activity this quarter? Lodge a nil BAS. It takes two minutes and keeps you clean with the ATO.

What if I stuff it up or lodge late?

Lodging late can attract a failure-to-lodge penalty and interest, but the ATO is far more forgiving of someone who lodges late and talks to them than someone who goes quiet. If you cannot pay, lodge anyway and set up a payment plan. If you made a mistake, BAS figures can be revised.

And if the whole thing makes your stomach drop, a registered BAS agent or bookkeeper is a normal, legitimate cost of running a business, not an admission of failure. Plenty of very good tradies never touch their own BAS.

FAQ

Do I have to lodge a BAS if I made no money this quarter? Yes. Lodge a nil BAS. The ATO expects a statement for every period you are registered, even a quarter with no activity, and a nil lodgement is quick to do online.

How often do I lodge a BAS? Most small businesses lodge quarterly. Some lodge monthly or annually depending on turnover and what the ATO assigned when you registered. Your BAS itself shows your cycle and due date.

Can I do my own BAS or do I need an accountant? You can absolutely do your own online, especially on Simpler BAS with three numbers. A BAS agent or bookkeeper is optional, and worth it once you have staff or messy records.

What is the difference between 1A and 1B? 1A is the GST you collected on your sales. 1B is the GST you paid on business purchases. You pay the ATO the difference, or receive a refund if 1B is bigger.

What happens if I lodge my BAS late? Possibly a failure-to-lodge penalty and interest. Lodge as soon as you can anyway, and contact the ATO about a payment plan if you cannot pay. Lodging late beats not lodging.

Sorting your invoices as you go is what makes BAS a non-event. Chippie's free tier tracks the GST on every invoice you send, so the collected side is already added up when the quarter ends. Free for one user, no card needed.