Free Tool • BAS Ready

GST Calculator Australia — BAS & GST Obligations

Instantly convert GST inclusive/exclusive amounts and estimate BAS GST payable

Fast, free calculator optimized for Australian businesses with CSV export

How to Use This Calculator

Enter Your Details

  • Annual revenue (GST inclusive/exclusive)
  • Annual expenses (GST inclusive/exclusive)
  • Select GST registration status
  • Choose quarterly or monthly BAS

Review Results

  • GST collected on sales
  • GST paid on purchases
  • Net GST payable/refundable
  • Export as PDF or CSV

How to Use This Calculator

Enter Your Figures

  • • Total revenue (sales/income) for the period
  • • Total expenses (purchases/costs) for the period
  • • Specify if GST is included or excluded
  • • Calculator works for any period (BAS or annual)

Instant BAS Results

  • • GST collected from customers
  • • GST paid on business expenses
  • • Net GST owing or refund
  • • Clear breakdown for BAS lodgement

Calculator will extract GST from your amounts (divide by 11)

$

Enter your total sales or income

$

Enter your business expenses

Understanding GST in Australia

Goods and Services Tax (GST) is a 10% broad-based tax on most goods, services and other items sold or consumed in Australia. If you're registered for GST, you need to include it in your prices and remit the difference to the ATO through your Business Activity Statement (BAS).

GST Collected

The GST you charge your customers on sales. This is 10% of the GST-inclusive price.

GST Paid

The GST you pay on business purchases and expenses. This is 10% of the GST-inclusive purchase price.

Net GST Amount

Your net GST obligation is calculated as: GST Collected - GST Paid

  • If positive: You owe this amount to the ATO
  • If negative: The ATO owes you a refund
  • If zero: Your GST obligations are balanced

Business Activity Statement (BAS)

The BAS is your main way of reporting and paying your business tax obligations to the ATO. GST-registered businesses must lodge a BAS quarterly or monthly depending on your turnover.

Lodgement Frequencies

  • • Monthly: If turnover > $20 million
  • • Quarterly: If turnover $2-20 million
  • • Annual: If turnover < $2 million (with activity statement)

Due Dates

  • • Monthly: 21st of the following month
  • • Quarterly: One month after quarter end
  • • Annual: 31 May (following tax year)

GST Tips for Businesses

✅ Keep Accurate Records

Maintain detailed records of all GST-inclusive and GST-exclusive transactions. Use accounting software to track GST automatically.

✅ Understand GST Treatment

Some items are GST-free (basic food, education) or input-taxed (financial services, residential rent). Know what applies to your business.

✅ Claim Input Tax Credits

Don't forget to claim GST credits on business purchases. This reduces your net GST payable or increases your refund.

✅ Lodge on Time

Late lodgement penalties apply. Set up reminders and use accounting software to ensure timely BAS submission.

💡 Track Your GST Automatically

Stop calculating manually. Upload receipts and track all your GST-eligible expenses in one place.

2-minute setup
No credit card required
Free tier available

Join 500+ Australians already tracking their tax deductions

Understanding GST in Australia

Goods and Services Tax (GST) is a 10% tax applied to most goods and services sold in Australia. As a business registered for GST, you collect GST from customers and pay GST on business purchases, reporting the net amount to the ATO via your Business Activity Statement (BAS).

Key concept: Your BAS reports the difference between GST collected (from sales) and GST paid (on purchases). If you collected more than you paid, you owe the ATO. If you paid more, you get a refund.

How to Use This Calculator

GST Inclusive/Exclusive

Convert between GST-inclusive prices (what customers pay) and GST-exclusive amounts (your base price). Enter any amount and instantly see:

  • • GST component (10% of exclusive amount)
  • • Base amount (excluding GST)
  • • Total including GST

BAS GST Calculation

Estimate your BAS GST obligation by entering total sales and purchases for the period. The calculator shows:

  • • GST collected on sales
  • • GST paid on purchases
  • • Net GST payable (or refundable)

Common GST Calculations Explained

Adding GST (10% to price)

Example: Product costs $100 (ex GST)

• GST amount: $100 × 10% = $10

• Price including GST: $100 + $10 = $110

Quick formula: Multiply by 1.1 (e.g., $100 × 1.1 = $110)

Removing GST (reverse calculation)

Example: Customer paid $110 (inc GST)

• Base amount: $110 ÷ 1.1 = $100

• GST component: $110 - $100 = $10

Quick formula: Divide by 11 to get GST (e.g., $110 ÷ 11 = $10)

Calculating BAS Net GST

Example: Quarter sales $55,000 (inc GST), purchases $33,000 (inc GST)

• GST collected: $55,000 ÷ 11 = $5,000

• GST paid: $33,000 ÷ 11 = $3,000

• Net GST payable: $5,000 - $3,000 = $2,000

Common GST Mistakes to Avoid

❌ Multiplying by 0.1 instead of dividing by 11

To extract GST from an inclusive price, divide by 11, not multiply by 0.1. Example: $110 inc GST → GST is $110÷11=$10, not $110×0.1=$11.

❌ Forgetting GST-free items

Some items are GST-free (basic food, some medical, education). Don't include these in your GST calculations unless you're certain they attract GST.

❌ Mixing inclusive and exclusive amounts

Always clarify whether amounts are GST-inclusive or exclusive. Mixing them up leads to incorrect BAS reporting and potential penalties.

When to Use This Calculator

✅ Perfect For:

  • • Converting prices for quotes and invoices
  • • Estimating BAS GST before lodgement
  • • Checking supplier invoices for GST accuracy
  • • Planning cashflow for GST payments
  • • Quick GST calculations during bookkeeping

⚠️ Note:

  • • This is an estimate tool, not official BAS lodgement
  • • Always verify with your accounting software
  • • Consult your accountant for complex GST scenarios
  • • Check ATO guidance for GST-free items
⚠️

Important Disclaimer

This calculator provides estimates for GST obligations and BAS amounts. Actual GST treatment may vary based on your business structure, GST-free items, and input-taxed supplies. Always consult a registered tax agent or BAS agent for accurate GST advice and lodgement assistance.

💡 Save This Calculation Automatically

Track all your receipts and deductions in one place

2-minute setup
No credit card required
Free tier available

Join 500+ Australians already tracking their tax deductions