GST should be simple. You charge 10% on what you sell, you claim back the 10% on what you buy for business, and you send the difference to the ATO every quarter.
In practice, it gets confusing because not everything has GST. Bank fees? No GST. Insurance? Yes GST (mostly). Council rates? No. Uber? Yes. Government fines? No. Accounting fees? Yes.
This guide gives you one place to check. Bookmark it for BAS time.
GST basics in 60 seconds
- GST rate: 10% (always). No reduced rates in Australia.
- Registration threshold: $75,000 annual turnover (mandatory). Optional below that.
- How to calculate GST in a price: Divide the total by 11. A $110 purchase has $10 GST.
- How to add GST to a price: Multiply by 1.1. A $100 service becomes $110 inc GST.
- You charge GST on: Most goods and services you sell (if you are GST-registered).
- You claim GST on: Business purchases where the seller charged GST.
- BAS: Lodge quarterly. Report GST collected minus GST paid. Pay or get refunded the difference.
The complete GST status reference
Business income — what has GST
| Income type | GST? | Notes |
|---|---|---|
| Service fees you charge clients | Yes | If you are GST-registered |
| Product sales | Yes | Standard taxable supply |
| Interest earned | No | Input-taxed (financial supply) |
| Government grants | Varies | Check if grant is for a taxable supply |
| Insurance payouts | Yes (usually) | Decreasing adjustment may apply |
| Dividends received | No | Not a supply |
| Rent from commercial property | Yes | If you are GST-registered |
| Rent from residential property | No | Input-taxed |
Business expenses — claiming GST credits
| Expense | Claim GST? | BAS label |
|---|---|---|
| Materials (Bunnings, trade suppliers) | Yes | G11 |
| Fuel | Yes | G11 |
| Phone / internet | Yes | G11 |
| Office supplies (Officeworks) | Yes | G11 |
| Tools and equipment under $300 | Yes | G11 |
| Equipment over $300 | Yes | G10 (capital) |
| Vehicle purchase | Yes | G10 (capital) |
| Computer / laptop | Yes | G10 if over $300 |
| Commercial rent | Yes | G11 |
| Accounting fees | Yes | G11 |
| Legal fees | Yes | G11 |
| Uber / taxi | Yes | G11 |
| Software subscriptions (AU) | Yes | G11 |
| Insurance premiums | Yes | G11 (GST on premium only, not stamp duty) |
| Advertising (Google Ads, Meta) | Yes | G11 (if billed from AU entity) |
Expenses with NO GST (do not claim)
| Expense | Why no GST |
|---|---|
| Bank fees, merchant fees | Input-taxed financial supply |
| Interest on business loan | Input-taxed financial supply |
| Wages, superannuation | Not a taxable supply |
| Workers compensation insurance | Exempt from GST |
| Council rates | Government levy, not a supply |
| Vehicle registration | Government fee (CTP has GST, rego does not) |
| Government fines, penalties | Not a supply |
| Donations | Not a supply |
| Residential rent | Input-taxed |
| Stamp duty | Government duty |
| Basic food (groceries) | GST-free (but prepared food has GST) |
The magic number. To get the GST component of any GST-inclusive amount, divide by 11. $550 ÷ 11 = $50 GST.
The problem with bank statements
Your bank CSV shows the merchant name and amount. It does not show the GST breakdown. When you see "BUNNINGS MAROOCHYDORE -$247.50", you have to know that Bunnings charges GST, so the GST component is $247.50 ÷ 11 = $22.50.
For 300 transactions per quarter, doing this manually is painful. You have to look at every single line and decide:
- Is this a business expense or personal?
- Does this merchant charge GST?
- What category is this?
This is exactly the problem TaxBench solves. Upload your bank CSV, and the AI determines the GST status of every transaction based on the merchant name and description. It knows Bunnings charges GST, bank fees don't, and Coles groceries are GST-free (mostly). You review, correct, done.
Mixed-use expenses
If you use something for both business and personal (like a mobile phone or car), you can only claim the business portion of the GST. Common splits:
- Mobile phone: If 60% business use, claim 60% of the GST
- Car: Log your business km percentage. Claim that % of fuel, insurance, and servicing GST
- Home office: Calculate your floor area percentage. Claim that % of internet, electricity GST
Keep a record of how you calculated the split. The ATO can ask.
When you cannot claim GST (even if it was charged)
Some situations where GST was included in the price but you cannot claim it:
- Not registered for GST: You must be GST-registered to claim input tax credits
- No tax invoice: For purchases over $82.50 (inc GST), you need a valid tax invoice to claim
- Personal expenses: Even if a receipt shows GST, you cannot claim it if it was not a business purchase
- Entertainment: Client entertainment expenses generally cannot have their GST claimed (with some exceptions)
- Penalties and fines: Even if a late payment fee includes GST, some cannot be claimed
Stop guessing which expenses have GST
Upload your bank CSV to TaxBench. AI identifies the GST status of every transaction. Review it, correct any mistakes, and get your BAS summary in minutes.
Try TaxBench — $29 per upload →Sole traders, companies, trusts, partnerships. All Australian banks supported.
Quick formulas
| What you want | Formula | Example |
|---|---|---|
| GST in a price | Total ÷ 11 | $330 ÷ 11 = $30 GST |
| Price before GST | Total ÷ 1.1 | $330 ÷ 1.1 = $300 ex GST |
| Add GST to a price | Price × 1.1 | $300 × 1.1 = $330 inc GST |
| Net GST (BAS) | 1A − 1B | $5,000 − $3,200 = $1,800 to pay ATO |
Bottom line
GST tracking is not conceptually hard. The pain is in the volume: hundreds of transactions, each needing a GST status decision. The reference tables in this guide cover 90% of what sole traders encounter. For the other 10%, check the supplier's tax invoice or ask your accountant.
Or upload your bank CSV and let the AI figure it out for you.