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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.