Tax & Income guide · New Zealand
GST Inclusive vs Exclusive Prices — NZ Guide
Add or remove New Zealand’s 15% GST without the common subtraction error, and know when the calculator cannot decide whether GST applies at all.
Reviewed 26 August 2026
Reviewed by KiwiTools editorial team — NZ calculator researchers; tax settings checked against Inland Revenue
General information only, not tax, financial, employment or legal advice. Check your tax code, agreement and current Inland Revenue guidance for your circumstances.
Key points
Three numbers worth remembering
Add GST to an exclusive price by multiplying by 1.15.
Remove GST from an inclusive total by dividing by 1.15.
The GST sitting inside an inclusive price is 3/23 of that total—not 15% of it.
Add GST and remove GST without mixing up the base
The add and remove percentages look different because 15% is calculated from the exclusive price.
| Check | Correct operation | $200 example | $230 example |
|---|---|---|---|
| Add GST | Exclusive × 1.15 | $200 → $230 | Not applicable |
| Remove GST | Inclusive ÷ 1.15 | Not applicable | $230 → $200 |
| GST component | Exclusive × 15% or inclusive × 3/23 | $30 | $30 |
| Wrong shortcut | Do not subtract 15% from inclusive | — | $230 − 15% = $195.50 |
Adding GST starts from the smaller number
A $480 quote excluding GST attracts $72 of GST, producing a $552 total. The arithmetic is $480 × 0.15 for the tax or $480 × 1.15 for the inclusive price.
Write “plus GST” or “including GST” beside the amount. Most spreadsheet mistakes are recoverable; a customer discovering the basis only after accepting a quote is a relationship problem as well as an arithmetic one.
Read the related nz income tax brackets guideRead the related how paye works guide
Removing GST is not subtraction by 15%
From the $552 inclusive total, divide by 1.15 to recover $480. Subtracting 15% gives $469.20, which is wrong because the original $72 was 15% of $480—not 15% of $552.
The tax component inside an inclusive amount is 3/23. Here, $552 × 3 ÷ 23 is $72. The exclusive base can also be found as 20/23 of the total.
Choose one rounding method and keep the trail
An invoice with many lines can differ by a cent depending on whether GST is rounded per line or on the subtotal. Use the accounting method required for the transaction and keep the net, tax and gross figures visible.
For a quick quote, calculate at full precision and round currency at the output. Repeatedly copying a rounded intermediate amount can create a larger mismatch across a long invoice.
The calculator cannot classify the supply
New Zealand’s standard rate is 15% for most taxable supplies, but zero-rated, exempt and mixed transactions exist. Residential rent, some land transactions and international supplies can follow different rules.
Arithmetic is the easy half. Whether a seller is registered, whether GST must be charged and whether a buyer can claim it are tax questions. Use Inland Revenue guidance or an adviser when the classification is uncertain.
Frequently asked questions
How do I add GST in New Zealand?
Multiply the exclusive price by 1.15. The GST component is the exclusive price multiplied by 0.15.
How do I remove GST?
Divide the inclusive total by 1.15, or multiply it by 20/23 to find the exclusive amount.
Why is GST 3/23 of an inclusive price?
Because $115 contains $15 GST: 15/115 simplifies to 3/23.
Can I subtract 15% from an inclusive price?
No. That calculates 15% of the larger inclusive total and removes too much.
Does every price in New Zealand include GST?
No. The seller, customer context and supply type matter. Confirm whether an amount is expressly inclusive or exclusive.
Can an unregistered business charge GST?
GST registration and charging rules are legal tax matters. Check current Inland Revenue guidance rather than using the calculator to infer registration.
Put the guide into practice
Continue with related KiwiTools calculators
Test your own numbers, compare scenarios and return to the guide to check assumptions and limitations.