How GST is calculated

GST can be added to a base amount or removed from a GST-inclusive amount. The selected rate should match the applicable classification for the transaction.

Adding GST

Multiply the base amount by the rate, then add that GST amount to the base amount.

Removing GST

Divide the inclusive amount by one plus the rate, then subtract the base amount from the inclusive amount.

Rate applicability

Common selections are shortcuts only. The applicable rate depends on the relevant goods or services classification.

Frequently asked questions

How do I add GST?

Enter the base amount, select a rate and use Add GST.

How do I remove GST?

Enter the inclusive amount, select a rate and use Remove GST.

Calculations are based on the formulas and assumptions shown. Actual financial outcomes may differ.

Use the GST calculator