What Is a BAS and How Do You Lodge It? A Plain-English Guide for Australian Small Businesses
Business Activity Statements don't have to be stressful. Here's everything you need to know about BAS — what it is, when it's due, and how to lodge it without the headache.
If you run a small business in Australia and you’re registered for GST, you’ve almost certainly heard the term BAS. For many business owners it’s one of those things that sits in the back of your mind, generating a low hum of anxiety every quarter. It doesn’t have to be that way.
This guide breaks down what a Business Activity Statement actually is, when you need to lodge one, and how to make the whole process painless.
What is a BAS?
A Business Activity Statement is a form you submit to the Australian Taxation Office (ATO) to report and pay several tax obligations, including GST, PAYG instalments, PAYG withholding, and fringe benefits tax.
Think of it as a regular check-in with the ATO. You’re telling them how much GST you collected from customers, how much GST you paid on business purchases, and the difference — which you either owe or get refunded.
Who needs to lodge a BAS?
You need to lodge a BAS if your business is registered for GST. In Australia, GST registration is mandatory once your annual turnover reaches $75,000 (or $150,000 for not-for-profits). Even if you’re under that threshold, you can voluntarily register — which can sometimes work in your favour if you’re claiming a lot of GST credits on purchases.
How often do you lodge?
Most small businesses lodge quarterly, but you have options. If your turnover is $20 million or more, you’ll need to lodge monthly. Some businesses with a turnover under $10 million can elect to lodge annually, though quarterly is by far the most common.
The quarterly due dates are straightforward: 28 October, 28 February, 28 April, and 28 July. If the 28th falls on a weekend or public holiday, you get until the next business day.
What goes into a BAS?
The core of your BAS is the GST calculation. You’ll report your total sales for the period, the GST you collected on those sales, your total purchases, and the GST you paid on those purchases. The difference between GST collected and GST paid is what you owe (or what the ATO owes you).
Beyond GST, your BAS might also include PAYG withholding if you have employees, PAYG income tax instalments on your own business income, and any other taxes relevant to your situation.
How to lodge your BAS
There are a few ways to lodge. You can do it yourself through the ATO’s online portal (myGov), use accounting software that lodges directly, or have your accountant or BAS agent handle it.
The simplest approach for most small businesses is to use accounting software that tracks your GST automatically throughout the quarter. When it’s time to lodge, the numbers are already there — you just review and submit. No frantic receipt-hunting required.
Common BAS mistakes to avoid
The most frequent errors come from poor record-keeping during the quarter. Claiming GST credits on purchases that don’t include GST, forgetting to include all income, or mixing up GST-free and taxable supplies can all lead to problems.
Another common issue is waiting until the deadline to start preparing. If your books aren’t up to date, you’ll be scrambling — and that’s when mistakes happen.
Making BAS simple
The best way to take the stress out of BAS is to keep your books current throughout the quarter. When your bank transactions are reconciled regularly and your invoices are categorised correctly, your BAS practically prepares itself.
Modern accounting software can automate most of this. Bank feeds pull in transactions daily, smart categorisation handles the repetitive work, and when the quarter ends, your BAS figures are ready to review in minutes rather than hours.
That’s the goal: spend your time running your business, not wrestling with compliance paperwork.