If your business earns (or expects to earn) $75,000 or more per year, you need to register for GST.
It’s one of those rules that can creep up on small business owners — and if you miss it, the ATO may backdate your registration, charge penalties, and hit you with interest. Whether you’re running a startup, a side hustle, or a family business, this blog will help you understand if you need to register and what happens if you don’t.
When do you need to register for GST?
Most businesses must register for GST when:
- Your GST turnover is $75,000 or more per year
- You expect to hit that threshold in your first year
- You drive for Uber, deliver for a rideshare app, or operate a taxi or limo service (no threshold — registration is mandatory)
- You run a non-profit with $150,000+ turnover
- You want to claim fuel tax credits
If you’re not sure where you sit, it’s a good idea to check monthly whether you’ve passed the threshold — or are likely to. The ATO gives you 21 days to register once you’re required to do so.
How to work out your GST turnover
Your GST turnover is your total business income, excluding:
- GST itself
- Sales not connected with your business
- Input-taxed sales (like residential rent)
- Private or overseas sales
You’ll need to consider:
- Your past 12 months’ income (current GST turnover), and
- Your next 12 months’ forecast (projected GST turnover)
If either is $75,000 or more, you’re required to register.
Example: Barry is a sole trader selling car parts. In May, his income is $2,560, and his total for the past 12 months is $31,170 — under the threshold. But if his next 11 months look likely to exceed $75,000, he needs to register within 21 days of hitting that projection.
What happens if you don’t register when you should?
Failing to register can mean:
- Paying GST on past sales — even if you didn’t include it in your pricing
- Lodging backdated BAS statements
- Facing interest and penalties
In short, it can cost you money, time, and sleep. Especially if your records aren’t up to scratch.
If you realise you’ve missed a deadline, you can request to backdate your registration — but only up to 4 years (unless there’s evidence of fraud). The sooner you catch it, the easier it is to fix.
How to register for GST
If you need to register, make sure you have an Australian Business Number (ABN) first. Then you can register via ATO Online Services for Business, by phone, or through your registered BAS agent.
Once registered:
- You must charge 10% GST on taxable sales
- Issue tax invoices for sales over $82.50
- Lodge regular BAS statements
- Track accounts payable and receivable
- Claim GST credits on eligible business purchases
These obligations are where basic bookkeeping becomes critical — especially tracking accounts payable and receivable, and ensuring everything is compliant come BAS time.
Should I register even if I’m under the threshold?
GST registration is optional if you’re under $75,000. Some business owners choose to register early so they can claim GST on business expenses or look more established to clients or suppliers.
However, charging with GST included adds extra admin, which is why many owners outsource bookkeeping to keep things simple.
GST FAQs: What are small business owners asking?
What’s the easiest way to register for GST?
Online via the ATO or through your registered BAS or tax agent.
Can I claim GST on purchases made before I registered?
No — you can only claim GST credits from your official registration date.
Do I need separate registrations for multiple businesses?
No — one GST registration per ABN, even if you run several businesses.
Can bookkeeping help with GST compliance?
Absolutely. An affordable bookkeeping service for small businesses can keep you compliant, help with BAS, payroll, and more.
So, do you need to register?
If your annual turnover is $75,000 or more — yes, you need to register. If you’re under, it’s optional — but worth considering if you plan to grow quickly or want to claim GST credits.
Avoiding registration or leaving it too late can lead to financial stress, ATO scrutiny, and avoidable admin. The good news? You don’t have to figure it out alone.
At Simplify, we specialise in bookkeeping for small businesses and startups, with a friendly, affordable team that keeps your bookkeeping in order — so you can focus on growing your business.
Let’s take the stress out of your books. Get in touch with Simplify today.
