How to Calculate GST on a Price in Australia

How to calculate GST on a price

If you have a price that does not include GST and want to add 10% GST, multiply the price by 0.10 to calculate the GST amount. Then add the GST to the original price.

For example, if your price is $100 before GST:

How to add GST to a price

An easy way to add 10% GST to a GST-exclusive price is to multiply the price by 1.10.

For example:

This method gives you the final price including 10% GST directly.

How to remove GST from a GST-inclusive price

If a price already includes GST, you cannot simply subtract 10% from the total to remove the GST. The GST-inclusive price represents 110% of the original GST-exclusive price.

To find the price before GST, divide the GST-inclusive price by 1.10.

For example, if the total price is $110 including GST:

How to calculate the GST component of a GST-inclusive price

If you already have a GST-inclusive price and only want to know how much of that amount is GST, divide the total by 11.

For example, if a customer pays $550 including GST:

This is useful when you have a GST-inclusive amount and need to separate the GST component from the total.

GST calculation examples

Here are some common examples of GST calculations using the Australian 10% GST rate.

Example 1: Adding GST to $50

Example 2: Adding GST to $500

Example 3: Removing GST from $330

Example 4: Finding GST from $1,100 including GST

GST and Australian businesses

Whether you need to charge GST depends on your GST registration status and the type of sale. In general, a business with GST turnover of $75,000 or more must register for GST, although different rules can apply to certain businesses and activities.

Businesses below the threshold can also choose to register voluntarily in some circumstances.

If you are registered for GST, you generally include GST in the price of taxable sales and report the GST through your business activity statements.

Not every sale is treated the same way for GST purposes. Some goods and services can be GST-free or input taxed, so you should check the GST treatment that applies to your particular sale.

Common GST calculation mistakes

Subtracting 10% from a GST-inclusive price

If a price already includes GST, subtracting 10% from the total does not give you the correct GST-exclusive price. Divide the GST-inclusive price by 1.10 instead.

Confusing the GST amount with the GST-inclusive total

The GST component is only part of the final price. For a GST-inclusive amount, divide the total by 11 to find the GST component.

Adding GST when GST does not apply

Not every sale has the same GST treatment. Check whether the sale is taxable, GST-free or otherwise treated differently before adding GST to a price.

Rounding too early

When working with multiple items, rounding individual calculations too early can sometimes create small differences in the final total. Keep appropriate decimal precision during calculations and round the final amounts as needed.

Using GST on a quote or invoice

When preparing a quote or invoice, make it clear whether the prices shown include GST. If GST applies, clearly identify the GST amount and the final total.

For example, a GST-inclusive quote could show a subtotal of $500, GST of $50 and a total of $550.

Keeping the GST amount and final total clear can make it easier for both you and your customer to understand the price.

For more information about creating quotes, see our guide to writing a quote for a customer in Australia.