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New Zealand 15% GST Calculator

How to Correctly Calculate Goods & Services Tax Costs for New Zealand

These New Zealand GST calculators work out:

  • The GST to add to an GST Exclusive amount
  • The GST content of a GST Inclusive amount
  • The original costs based just on the GST amount

Enter any known amount into the appropriate box to calculate the other 2 figures.

  • Add 15% GST to a GST Exclusive Price
  • Find the GST component of a GST Inclusive Price
  • Find GST Exclusive Price from full cost including GST
Cost Excluding GST

GST Amount

Cost Including GST

The mathematics behind calculating GST in NZ

Basic GST Calculations.

Adding GST

Goods and Services Tax in NZ is 15%

To add 15% GST onto $100

  • $100 x 15% = $15 GST
  • $100 + $15 GST = $115 GST Inclusive.

Adding GST

Subtracting GST

Inland Revenue (IRD) recommends the following formula to find the GST amount from a GST inclusive price.

  • GST Inclusive Price X 3 ÷ 23 = GST Amount

Working backwards to find the GST and GST exclusive amounts from the total GST inclusive price.

  • $115 X 3 ÷ 23 = $15 GST

To work out the GST exclusive amount simply subtract the GST from the GST inclusive amount to get the original GST exclusive cost.

  • $115 – $15 GST = $100

We're now back to the start with a GST exclusive price.

When using the correct formula, you can see the $15 GST cost remains the same when adding GST on and finding the GST amount from the inclusive price.

Subtracting GST

Subtracting GST The Wrong Way! Don't Just Remove 15%

Just subtracting 15% from the GST inclusive price won't work.

  • 15% of $115 = $17.25 (not $15)

To subtract 15% from our $115 GST inclusive figure from above…

  • $115 – 15% = $97.75 (not $100)

Need help with anything else?

Contact Devine Accounting to book an initial consultation.