When to register business for GST (Australia)

Understanding when to register business for GST is one of the most important early decisions you’ll make as a small business owner. Register too early and you may create extra admin before you need it. Register too late and you could face unexpected tax bills, penalties, and cash flow stress.

Some business owners choose to register for GST from day one, even if they expect low income initially. Others — particularly sole traders and side-hustle operators — delay registration until it becomes compulsory. While both approaches can be valid, problems often arise when businesses don’t realise they’ve crossed the GST threshold.

If you exceed the threshold and haven’t registered, the ATO can require you to pay GST on sales anyway — even if you didn’t include GST in your prices. This can mean losing one-eleventh of your income, which can be a painful surprise for a growing business.

When is GST registration compulsory?

So, exactly when should you register your business for GST?

GST registration becomes compulsory when your business’s GST turnover reaches $75,000 or more in a financial year (or $150,000 for not-for-profit organisations). GST turnover generally includes your total sales, excluding GST itself.

A helpful rule of thumb is to break this down monthly:

  • If you’re consistently earning $6,250 or more per month, you’re on track to hit the $75,000 threshold.

  • At this point, you should closely review your turnover and future income expectations.

Good practice is to:

  • Review your turnover every quarter

  • Switch to monthly checks once you’re approaching the threshold

This regular monitoring is key to knowing when to register business for GST before it’s too late.

✅ Important: Once you exceed the threshold, you must register for GST within 21 days.

Using online accounting software can make this much easier. Real-time reports allow you to track turnover accurately and avoid accidentally missing the registration point.

What happens if you register too late?

Late registration can be costly. If the ATO determines you should have been registered earlier, they can:

  • Backdate your GST registration

  • Require you to pay GST on past sales

  • Apply penalties and interest in some cases

If your prices didn’t include GST, that GST often has to come out of your own pocket. This is why understanding when to register business for GST is so critical for protecting your income and cash flow.

Can you register for GST voluntarily?

Yes, you don’t have to wait until GST registration is compulsory.

If your turnover is under $75,000, you can voluntarily register for GST. Some reasons businesses choose to do this include:

  • Claiming GST credits on expenses

  • Appearing more established to clients or suppliers

  • Working with customers who expect GST-registered invoices

If you voluntarily register, you may also be eligible to lodge an annual BAS, rather than quarterly, which can reduce compliance time for small businesses.

However, voluntary registration isn’t right for everyone. It increases reporting obligations, so it’s worth weighing up the benefits before deciding when to register business for GST.

Special rules that affect when to register business for GST

In some situations, GST registration rules are different.

Ride-sharing and commercial driving

  • If you earn income through ride-sharing platforms such as Uber, Ola, or DiDi, you must register for GST immediately, regardless of turnover. All commercial ride-sharing income is subject to GST from the first dollar.

Fuel tax credits

  • If you want to claim fuel tax credits, your business must be registered for GST.

Not-for-profit organisations

  • Not-for-profit entities have a higher registration threshold of $150,000 per financial year, but the same monitoring principles apply.

Non-resident businesses

  • If your business is not an Australian resident, the rules for calculating GST turnover can differ. Getting advice before registering is important to ensure you comply correctly.

How to prepare before you reach the threshold

If you’re getting close to the GST threshold, preparation makes the transition smoother:

  • Review your pricing to ensure GST can be added without hurting margins

  • Set up or review your accounting software

  • Understand your BAS reporting obligations

  • Get advice on cash flow planning once GST applies

Being proactive helps you confidently manage when to register business for GST, rather than reacting under pressure.

Need help deciding when to register business for GST?

Starting and growing a business involves many decisions, and GST registration is just one of them — but it’s an important one. If you’re unsure when to register business for GST, we can review your turnover, explain the pros and cons of early registration, and help you get set up with the right accounting software so GST doesn’t become a burden as your business grows.