New Zealand GST calculator
Add GST to an exclusive price or extract the GST included in a total, in NZD.
Before you calculate. Select the treatment applicable to your supply. Human tax review is pending.
Provisional rounding: GST to cents, exact half-cents down. Current statutory rounding verification is incomplete; not an invoice-compliance tool.
Amount: up to two decimals and NZ$1,000,000,000,000. Manual percentage: up to six decimals and 1,000%. Non-negative inputs only; these are input caps, not legal limits.
Choose the treatment applicable to your supply. No rate is selected automatically.
- Excluding GST
- GST amount
- Including GST
Select the treatment to see the calculation and rounding assumptions.
Reference examples at 15% · add GST
Illustrative arithmetic, not a decision that these supplies are standard-rated.
| Input (NZD) | Excluding GST | GST | Including GST |
|---|---|---|---|
| NZ$100 | NZ$100.00 | NZ$15.00 | NZ$115.00 |
| NZ$115 | NZ$115.00 | NZ$17.25 | NZ$132.25 |
| NZ$2000 | NZ$2000.00 | NZ$300.00 | NZ$2300.00 |
Standard-rated, zero-rated and exempt
IRD distinguishes ordinary standard-rated supplies, zero-rated supplies that meet specific conditions, and exempt supplies. The 15% reference is for an ordinary supply already confirmed as standard-rated by a GST-registered seller. Choosing 0% does not establish zero-rating eligibility or input-tax entitlement. Exempt and outside-scope choices return no numerical calculation; they are not silently converted to zero-rated supplies.
Add GST or extract the included GST
For the standard reference: GST = exclusive price × 15 ÷ 100. For an inclusive price: GST = total × 3 ÷ 23. Subtract that GST component to obtain the exclusive price; do not subtract 15% of the total. The calculation keeps decimal precision until the GST component is rounded.
IRD's independent worked examples reconcile NZ$100 exclusive, NZ$15 GST and NZ$115 inclusive. Its charging guidance also gives NZ$13.04 GST within a NZ$100 inclusive price. These examples are regression fixtures, not a determination of your supply's tax treatment.
IRD worked examplesRounding and scope limits
This calculator rounds the GST component to the nearest cent, with exact half-cents down, then reconciles the other amount. This remains a provisional display policy, not a verified universal New Zealand rounding requirement.
Section 19O, read on the official legislation website on , describes optional rounding of tax amounts shown in taxable supply or correction information, with individual-amount or supply-total alternatives and consistency within a taxable period. The published version is dated . The publisher warns of amendments not yet incorporated; amendment applicability and professional review remain incomplete. This one-amount tool does not aggregate invoices or enforce taxable-period consistency.
Synthetic boundary: NZ$0.10 exclusive at 15% produces NZ$0.015 before rounding, displayed here as NZ$0.01 GST and NZ$0.11 total. This is a policy test, not an independent official example. Other country tools and the generic formula generator use different rounding policies; their midpoint results may differ.
One NZD amount only. No mixed baskets, line-item invoices, cash-payment rounding, refunds, registration decisions, property rules, imports/exports, special supplies, deductions, return filing or GST-credit calculations are implemented. Manual percentages are illustrative arithmetic and retain this calculator's disclosed rounding policy.
Internal technical assessment
This is our assessment of software checks, not a customer review or independent tax certification. Automated tests reproduce IRD's addition and extraction examples and check cent boundaries. Worked examples, chart and result use the same engine. Current-law rounding verification and professional review remain incomplete.
Official sources and dates
Latest source check: . Seven IRD texts matched the retained references. Section 19O was read directly in the official browser page after automated retrieval failed. Its amendment warning remains relevant. IRD's historical commentary dates the standard-rate change to . No historical or future transaction lookup is provided.
- IRD: What GST is Official guidance. Check conditions for your supply.
- IRD: Calculating your GST Official guidance. Check conditions for your supply.
- IRD: Charging GST Official guidance. Check conditions for your supply.
- IRD: Zero-rated supplies Official guidance. Check conditions for your supply.
- IRD: Exempt supplies Official guidance. Check conditions for your supply.
- IRD: 2010 GST rate increase and transition Historical reference, not confirmation of current applicability.
- IRD: Archived 1986 rounding commentary (historical only) Historical reference, not confirmation of current applicability.
- GST Act section 19O: fractional cent amounts Published section read on the official website; amendment applicability and professional review remain pending.