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How to calculate GST at 15% using Excel formulas

sharyn bainesI have been asked twice in one week to please explain how to calculate GST at 15% using Excel formulas.

You can find information on how to calculate GST  (Goods and Services Tax) on the NZ Inland Revenue website. I’ve taken this a step further and put together a tutorial on how to put these calculations into Excel formulas.


Calculate GST at 15% using Excel formulas

Download the example workbook and follow along with the instruction. We’ll also give you a ‘completed’ copy of the formulas so that you can check your formulas against the completed copy.

Get the workbook

Let’s start by calculating the GST component of a GST exclusive amount.  To do this you simply multiply the value, excluding GST by 15% or by 0.15.  To find the total including GST simply add the two values together.

Let’s now have a look at calculating the total including GST.  This time multiply the total by 115% or by 1.15

Now let’s look at writing a formula to calculate the GST content of a GST inclusive amount.  This formula contains two parts.  First, multiply the GST inclusive amount by 3 and then divide this figure by 23.


In the video tutorial below I show you in Excel how to calculate GST:

  • find the GST component to be added to a GST exclusive figure
  • calculate the total figure including GST
  • extract the GST component of a GST inclusive figure

The steps in the tutorial will work in Excel versions 2010, 2013 and 2016

For more information on our Microsoft Excel training courses please visit our Excel course information page.

For more assistance with understanding GST (Goods and Services Tax) within New Zealand please visit the NZ Inland Revenue page for all things GST related.

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