How to Calculate GST in Australia
The complete guide to adding, removing, and reporting GST for Australian businesses — with formulas, worked examples, BAS deadlines, and tax invoice rules.
In this guide
GST calculation — at a glance
- GST rate: 10% (flat rate since 1 July 2000)
- Add GST: Price × 1.1
- Remove GST: Price ÷ 1.1
- GST component only: Price ÷ 11
- Registration threshold: $75,000 annual turnover ($150,000 for non-profits)
- Car limit (2025-26): $69,674 — max GST credit of $6,334
- Tax invoice required: For GST credit claims on purchases over $82.50 inc GST
The three GST formulas
Every GST calculation in Australia comes down to three formulas. They all rely on the same 10% rate — the only GST rate in Australia since the tax was introduced on 1 July 2000.
1. Adding GST to a price
When you know the GST-exclusive price and need to calculate the total including GST, multiply by 1.1:
GST-inclusive price = Price (ex GST) × 1.1
This works because GST is 10% of the ex-GST price. Multiplying by 1.1 adds 10% in a single step. For example, $500 × 1.1 = $550 inc GST.
2. Removing GST from a price
When you have a GST-inclusive price and need the ex-GST amount, divide by 1.1:
GST-exclusive price = Price (inc GST) ÷ 1.1
This reverses the addition. For example, $550 ÷ 1.1 = $500 ex GST.
3. Finding the GST amount only
To extract just the GST component from a GST-inclusive price, divide by 11:
GST amount = Price (inc GST) ÷ 11
Why 11? Because a GST-inclusive price contains 11 equal parts — 10 parts are the ex-GST price and 1 part is the GST. Dividing by 11 isolates that 1 part. For example, $550 ÷ 11 = $50 GST.
Try it yourself
Enter any amount and instantly see the ex-GST price, GST component, and GST-inclusive total.
Try the GST CalculatorWorked examples
These examples cover the three most common situations where Australian businesses need to calculate GST: invoicing a client, processing a receipt, and preparing a quarterly BAS.
Example 1: Adding GST to a consulting invoice
A web designer charges $3,000 for a project (ex GST). They're GST-registered and need to issue a tax invoice:
| Calculation | Result |
|---|---|
| Subtotal (ex GST) | $3,000.00 |
| GST ($3,000 × 10% or $3,000 ÷ 10) | $300.00 |
| Invoice total (inc GST) | $3,300.00 |
The tax invoice must show the GST amount ($300) separately, or state "Total price includes GST".
Try it yourself
Calculate GST on a $3,000 consulting invoice and see the full breakdown.
Try this calculationExample 2: Removing GST from a receipt
A business buys office equipment for $880 inc GST. They need the GST-exclusive amount for bookkeeping and the GST amount for their BAS input tax credit:
| Calculation | Result |
|---|---|
| Total paid (inc GST) | $880.00 |
| GST amount ($880 ÷ 11) | $80.00 |
| Price ex GST ($880 ÷ 1.1) | $800.00 |
The $80.00 GST can be claimed as an input tax credit on the next BAS, provided the purchase is for a creditable business purpose and you hold a valid tax invoice.
Example 3: Calculating net GST for a quarterly BAS
A small business had $55,000 in sales (inc GST) and $22,000 in business purchases (inc GST) during Q3 (January–March 2026):
| BAS Line | Amount |
|---|---|
| 1A: GST on sales ($55,000 ÷ 11) | $5,000.00 |
| 1B: GST on purchases ($22,000 ÷ 11) | $2,000.00 |
| Net GST payable to ATO | $3,000.00 |
The business owes $3,000 to the ATO — the difference between GST collected on sales and GST paid on purchases. If purchases exceed sales, the ATO refunds the difference.
What this means for you
For a business with $200,000 annual turnover (all taxable, inc GST)
~$18,182 in GST collected per year
That's roughly $4,545 per quarter reported on your BAS. Your actual payment to the ATO will be lower after subtracting input tax credits on business purchases.
BAS Estimator
Enter your quarterly sales and purchases to estimate your net GST payable or refund.
Quick reference: common GST calculations
The table below shows GST breakdowns for amounts Australian businesses deal with regularly — from invoices and contractor quotes to rent and software subscriptions.
| Scenario | Ex GST | GST | Inc GST |
|---|---|---|---|
| Freelancer invoicing $2,000 | $2,000.00 | $200.00 | $2,200.00 |
| Retail sale of $49.95 inc GST | $45.41 | $4.54 | $49.95 |
| Contractor quote $15,000 | $15,000.00 | $1,500.00 | $16,500.00 |
| Commercial rent $5,500/month | $5,000.00 | $500.00 | $5,500.00 |
| Office supplies $330 inc GST | $300.00 | $30.00 | $330.00 |
| SaaS subscription $109 inc GST | $99.09 | $9.91 | $109.00 |
| Consulting day rate $1,650 | $1,500.00 | $150.00 | $1,650.00 |
When to register for GST
Not every business needs to register for GST. Whether you must register depends on your annual GST turnover and what type of business you run.
Mandatory registration
You must register for GST if:
- Your business has a current or projected GST turnover of $75,000 or more per year
- Your non-profit organisation has a turnover of $150,000 or more per year
- You provide taxi or ride-sharing services (e.g. Uber, Didi) — regardless of turnover
- You want to claim fuel tax credits for your business
The $75,000 threshold is assessed on a rolling 12-month basis — both looking back at the past 12 months and forward at the next 12 months. Once you hit the threshold, you have 21 days to register.
Voluntary registration
If your turnover is below $75,000, you can still choose to register. This is often worthwhile if you regularly purchase from GST-registered suppliers, as you'll be able to claim input tax credits on those purchases. However, once registered, you must charge GST on all your taxable sales and lodge BAS returns.
What you must do once registered
- Include GST in the price of taxable goods and services you sell
- Issue tax invoices when requested by GST-registered buyers
- Lodge Business Activity Statements (BAS) — usually quarterly
- Pay the net GST amount to the ATO by the due date
- Keep GST records for at least 5 years
ATO Reference
Registering for GST
Official ATO guidance on when to register, how to register online, and your obligations once registered.
View on ATO websiteGST Registration Threshold Checker
Enter your turnover to check whether you need to register for GST.
Taxable vs GST-free vs input taxed sales
Not everything sold in Australia attracts GST. The tax law classifies supplies into three categories, each with different GST treatment and different rules for claiming input tax credits.
| Type | GST Treatment | Examples |
|---|---|---|
Taxable | 10% GST applies | Most goods & services, commercial rent, consulting fees, software subscriptions |
GST-free | No GST charged | Fresh food, medical services, education, childcare, exports, water & sewerage |
Input taxed | No GST charged, no input tax credits | Residential rent, financial services (loans, share trading), some insurance premiums |
Key distinction: With GST-free sales, you don't charge GST but you can still claim input tax credits on related business purchases. With input taxed sales, you don't charge GST and you cannot claim input tax credits on related purchases. This makes the input taxed category more costly for businesses.
What this means for you
For a medical practice (GST-free services) spending $50,000/year on business supplies (inc GST)
~$4,545 in reclaimable GST credits per year
Even though you don't charge GST on your services, you can still claim back GST on equipment, rent (if commercial), and other business purchases.
ATO Reference
Types of supplies — taxable, GST-free, and input taxed
The ATO's breakdown of how different types of supplies are treated for GST purposes.
View on ATO websiteTax invoice requirements
If you're GST-registered, you must issue a tax invoice within 28 days of a request from a GST-registered buyer. Tax invoices are also critical for claiming input tax credits — you need one for any purchase over $82.50 (inc GST).
What must be on a tax invoice?
| Required Information | Under $1,000 | $1,000 or more |
|---|---|---|
| Seller's identity (name or business name) | Yes | Yes |
| Seller's ABN | Yes | Yes |
| Date of issue | Yes | Yes |
| Description of items sold | Yes | Yes |
| GST amount (or statement that total includes GST) | Yes | Yes |
| Total price including GST | Yes | Yes |
| Buyer's identity or ABN | No | Yes |
| Quantity of each item | No | Yes |
The $82.50 rule
For purchases of $82.50 or less (inc GST), you can claim a GST credit without a tax invoice. This covers most small day-to-day expenses like stationery, parking, and coffee for a client meeting. Above $82.50, you need a valid tax invoice or you risk the ATO disallowing the credit.
Digital tax invoices
Tax invoices don't need to be paper. PDFs, emails, and electronic invoices all count, as long as they contain the required information. The ATO accepts any format that can be retrieved and read.
ATO Reference
Tax invoices
Full ATO guidance on when to issue tax invoices, what information they must contain, and special rules for recipient-created tax invoices.
View on ATO websiteInvoice GST Calculator
Build a multi-line invoice with GST breakdowns per item, category totals, and export options.
BAS reporting & deadlines
Once registered for GST, you report and pay your GST through your Business Activity Statement (BAS). Most small businesses lodge quarterly, though monthly and annual options exist.
Quarterly BAS deadlines — 2025-26 financial year
| Quarter | Period | Self-lodgement |
|---|---|---|
Q1 | Jul – Sep 2025 | 28 Oct 2025 |
Q2 | Oct – Dec 2025 | 28 Feb 2026 |
Q3 | Jan – Mar 2026 | 28 Apr 2026 |
Q4 | Apr – Jun 2026 | 28 Jul 2026 |
If you lodge online, you may get an extra 2 weeks for quarters 1, 3, and 4. Quarter 2 already includes a one-month extension (28 Feb instead of 28 Jan), so no additional time applies.
Simpler BAS
Since 2017, small businesses with GST turnover under $10 million use Simpler BAS by default. This means you only need to report three fields for GST: G1 (total sales), 1A (GST on sales), and 1B (GST on purchases). The ATO no longer requires you to report export sales, GST-free sales, or capital purchases separately on Simpler BAS.
What the BAS fields mean
G1 — Total sales: Your total sales for the period (including GST-free sales). This is the GST-exclusive amount if you use accrual accounting, or the amount received if you use cash accounting.
1A — GST on sales: The total GST you've collected on your taxable sales. For most businesses, this is your taxable sales divided by 11.
1B — GST on purchases: The total GST included in your business purchases (your input tax credits). Subtract this from 1A to get your net GST payable.
Net GST = 1A − 1B. If the result is positive, you owe the ATO. If negative, you're entitled to a refund.
ATO Reference
Due dates for lodging and paying your BAS
The ATO's official BAS due dates, including options for electronic lodgement extensions.
View on ATO websiteCash vs accrual GST accounting
How you account for GST affects when you report it on your BAS. There are two methods, and the right choice depends on your business size and cash flow.
Cash basis
Report GST in the period you receive or make payment.
- Simpler for small businesses
- You don't owe GST on unpaid invoices
- Better for businesses with long payment terms
- Available if turnover is under $10 million or you use cash accounting for income tax
Accrual (non-cash) basis
Report GST when you issue or receive an invoice, regardless of payment.
- Matches GST to the period the sale or purchase occurred
- Required for businesses over $10 million turnover
- Better reflects your true financial position
- You may owe GST before the customer has paid you
What this means for you
For a tradie who invoices $16,500 (inc GST) in March but doesn't get paid until May
Cash basis: report $1,500 GST in the Apr–Jun quarter (Q4)
On cash, you report when paid (May = Q4). On accrual, you'd report in Jan–Mar (Q3) when invoiced — even though you haven't been paid yet.
Common GST mistakes to avoid
The ATO actively audits GST compliance. These are the most common errors that trigger scrutiny or result in penalties — and how to avoid them.
1. Claiming GST credits without a valid tax invoice
For purchases over $82.50 (inc GST), you must hold a valid tax invoice to claim the GST credit. Without it, the ATO can disallow the claim.
2. Claiming GST on purchases that are input taxed or GST-free
There's no GST to claim on bank fees (input taxed), fresh food (GST-free), or wages. Check the GST status before claiming credits.
3. Not apportioning GST for mixed-use purchases
If a purchase is used partly for business and partly for personal use (e.g. a car used 60% for business), you can only claim 60% of the GST credit.
4. Reporting GST-inclusive amounts where GST-exclusive amounts are required
BAS labels G1 (total sales) should be GST-exclusive if you report on a non-cash basis. Mixing up inclusive and exclusive figures inflates your GST payable.
5. Missing the registration threshold and charging GST late
Once your GST turnover reaches $75,000 in a 12-month period (past or projected), you have 21 days to register. The ATO can backdate your GST obligations to when you should have registered.
6. Forgetting GST on asset sales
Selling a business asset (vehicle, equipment, property) that you claimed GST credits on is a taxable sale. You must include 1/11th of the sale price as GST on your BAS.
Correcting BAS errors
If you discover a GST error, you can usually correct it on your next BAS rather than revising the original — provided the net error is under $10,000 and you correct it within 4 years. Voluntarily correcting errors means you won't face penalties for the mistake.
Input Tax Credit Checker
Check whether you can claim GST credits on a specific purchase — with decision-tree guidance.
GST on imports & digital services
GST applies to most goods and services imported into Australia, including digital products purchased from overseas suppliers.
Imported goods over $1,000
For goods valued over $1,000, GST is collected by Australian Border Force at the point of import. You pay 10% of the customs value (the price of the goods, excluding international freight and insurance). If the goods are for business use, you can claim the GST back as an input tax credit on your next BAS.
Low-value imported goods ($1,000 or less)
Since 1 July 2018, overseas suppliers with Australian sales exceeding $75,000 must register for Australian GST and collect 10% GST at the point of sale. This applies to physical goods sold via online marketplaces and shipped to Australian consumers. If you're a GST-registered business and provide your ABN, the overseas supplier should not charge you GST (you'll account for it via reverse charge if applicable).
Digital products and services
Since 1 July 2017, GST applies to digital products and services supplied to Australian consumers by non-resident businesses. This includes streaming subscriptions (Netflix, Spotify), e-books, software, online courses, and digital consulting services. Major platforms like Google, Apple, and Amazon collect and remit GST on these sales automatically.
ATO Reference
GST on imported services, digital products and low value goods
ATO guide covering how GST applies to goods and digital services purchased from overseas suppliers.
View on ATO websiteNeed to calculate GST quickly?
Our calculator instantly adds or removes 10% GST, generates invoice breakdowns, and estimates your quarterly BAS — all based on current ATO rates for 2025-26.
Use the GST Calculator →Frequently asked questions
Related guides
GST-Free Items in Australia
Full list of goods and services exempt from GST, with examples and edge cases.
GST Registration Threshold
When you must register, how the $75K threshold works, and voluntary registration pros and cons.
Contractor vs Employee Tax
How GST, income tax, and super obligations differ for contractors and employees.
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