You have just landed a run of bigger jobs, revenue is climbing, and somewhere in the back of your mind a question is nagging: do I need to register for GST yet? Get the timing wrong and you can end up personally out of pocket, paying the ATO 10% on sales you never charged GST on, plus penalties.

Most business owners we meet either register too late and cop a nasty bill, or register too early and take on paperwork they did not need. Neither is fatal, but both are avoidable.

This guide explains exactly when you have to register for GST in Australia, when it is worth doing voluntarily, how to register, and what changes the day you do. It is written for established Melbourne business owners who want to get this right and move on.

What is GST registration, in plain English?

GST (Goods and Services Tax) is a flat 10% tax on most goods and services sold in Australia. When your business is registered for GST, you add 10% to your prices, collect it from your customers, and pass it on to the ATO through your Business Activity Statement (BAS). In return, you can claim back the GST you pay on your own business purchases; these are called GST credits.

Registration is what switches all of this on. Until you are registered, you must not charge GST; once you are registered, you must. That is why the timing matters so much.

The $75,000 GST registration threshold

The core rule is simple. You must register for GST when your business’s GST turnover reaches $75,000 or more in a 12-month period. Turnover here means your gross income from sales, not your profit, and before expenses.

This catches NDIS providers in particular, because GST-free supports still count towards the threshold. Our guide to GST on NDIS therapy services explains which supports are actually GST-free and which are not.

Critically, the test is forward-looking as well as backward-looking. You have to register if either of these is true:

• Your current GST turnover, this month plus the previous 11 months, is $75,000 or more; or
• Your projected GST turnover, this month plus the next 11 months, is likely to be $75,000 or more.

That projected test catches a lot of growing businesses. If you sign a contract or win work that you know will push you over $75,000 in the coming year, the obligation to register is triggered then, not at the end of the financial year.

A few important variations on the threshold:

• Non-profit organisations have a higher threshold of $150,000.
• Taxi, limousine and ride-sourcing drivers (including rideshare) must register for GST regardless of turnover; there is no threshold at all.
• If you want to claim fuel tax credits, you must be registered for GST.

You have 21 days: do not sit on it

Once you become aware that your turnover has reached, or will reach, the threshold, you have 21 days to register. Miss that window and the ATO can require you to pay GST on all the sales you made from the date you should have registered, even though you never charged your customers that 10%. On $200,000 of sales, that is roughly $18,000 coming straight out of your margin, plus potential penalties and interest.

This is the single most expensive GST mistake we see. It is entirely preventable with a bit of forward planning and someone keeping an eye on your rolling turnover.

Should you register for GST voluntarily?

If your turnover is under $75,000 you can still choose to register. Whether you should comes down to who your customers are and what you buy.

When voluntary registration makes sense

• Your customers are other businesses. They claim back the GST you charge, so your 10% is not a real cost to them, and you get to claim GST credits on your own purchases.
• You have significant start-up or equipment costs. Registering lets you claim back the GST on those purchases, which can be a meaningful cash refund early on.
• You are close to the threshold anyway. Registering early avoids the scramble, and the risk of blowing past $75,000 without noticing.

When it is usually not worth it

• You sell mostly to consumers (the general public), who cannot claim the GST back, so adding 10% either makes you dearer than competitors or eats your margin.
• You want to keep BAS paperwork and cash-flow management to a minimum while you are small.

How to register for GST

You need an Australian Business Number (ABN) before you can register for GST; the two are linked. Once you have an ABN, you can register in a few ways:

• Through the ATO’s Business Portal or the ATO’s registering for GST page;
• Through the online Business Registration Service when you first apply for your ABN;
• By phoning the ATO; or
• Through your registered tax or BAS agent, the simplest option, because they confirm the right registration date and reporting cycle for you.

When you register you will also choose how often you lodge your BAS, usually quarterly for small business, though monthly and annual options exist. Getting this cycle right matters for cash flow.

What changes the day you are registered

Registration brings three ongoing obligations:

• Charge 10% GST on your taxable sales and issue tax invoices that show the GST.
• Lodge a BAS each period, reporting the GST you collected and the GST credits you are claiming.
• Pay the net GST to the ATO (or receive a refund if your credits exceed what you collected).

Coding your transactions correctly from day one keeps this clean; our guide on GST coding walks through the common traps. If you want the mechanics of the statement itself, start with what a BAS actually is and the key lodgement dates.

At registration you also choose how you will report GST. That choice is worth real money if your customers pay slowly, so read GST cash vs accruals before you accept the default.

Frequently Asked Questions

• Facebook
• Instagram
• LinkedIn
• YouTube
• TikTok
• X