NZ GST Calculator — 15% Add & 3/23 Extract
Add 15% GST or extract embedded GST using New Zealand's official 3/23 statutory fraction with instant penny precision and multi-item quote builder.
Add 15% GST or extract embedded GST using New Zealand's official 3/23 statutory fraction with instant penny precision and multi-item quote builder.
Add 15% GST or extract embedded GST using New Zealand's official 3/23 statutory fraction with instant penny precision and multi-item quote builder. Calculate exact, penny-accurate projections compliant with 2026 Inland Revenue (IRD) • ACC • Reserve Bank of New Zealand (RBNZ) standards using Calconova's deterministic IEEE-754 (Decimal.js) calculation engine with instant breakdowns.
Adds 15% GST to the net base amount
Inland Revenue requires multiplying by 3 and dividing by 23 to eliminate recurring decimal rounding errors on GST returns.
\text{Add GST (Exclusive to Inclusive):} \\
GST = Amount_{Excl} \times 15\% \\
Amount_{Incl} = Amount_{Excl} \times 1.15 \\
\\
\text{Extract GST (Inclusive to Exclusive):} \\
GST = Amount_{Incl} \times \frac{3}{23} \approx Amount_{Incl} \times 0.1304348 \\
Amount_{Excl} = Amount_{Incl} \times \frac{20}{23}Under New Zealand Goods and Services Tax Act 1985, standard GST is 15%. To extract the embedded tax from a GST-inclusive price, Inland Revenue specifies multiplying by 3 and dividing by 23 (15 / 115 simplifies exactly to 3 / 23). This guarantees zero rounding discrepancy compared to dividing by 1.15.
All calculations, amortizations, and scenario projections displayed on this page are strictly for informational and educational purposes. Nothing herein constitutes investment, financial, tax, or legal advice. Actual Reserve Bank of New Zealand (RBNZ) interest rates, IRD PAYE brackets, ACC Earner's Levy, KiwiSaver regulations, and lender criteria may vary. Calconova explicitly disclaims all liability for any decisions taken based upon these calculations. Consult a qualified financial advisor, CPA, or official Inland Revenue documentation prior to executing financial commitments.
The standard Goods and Services Tax (GST) rate in New Zealand is 15%. This rate has been in effect since 1 October 2010, when it was increased from 12.5%.
In a GST-inclusive price, if the net cost is 100 and GST is 15, the gross total is 115. The proportion of GST in the gross price is 15 / 115, which reduces mathematically to 3 / 23 (approximately 13.0435%).
Any business, sole trader, or contractor with an annual turnover exceeding $60,000 in the past 12 months, or expected to exceed $60,000 in the next 12 months, is legally required to register for GST with Inland Revenue.
Exports of goods and services outside New Zealand are zero-rated (0% GST). Residential rental income, mortgages, bank interest, and financial services are exempt supplies where GST is not charged.
Calculate NZ sole trader income tax, ACC CoverPlus levies, 3-instalment provisional tax obligations, and recommended Hnry-style invoice set-aside percentages.
Calculate IRD Schedule 4 Withholding Tax (WT code) deductions on contractor invoices, GST components, net payouts, and end-of-year tax reconciliation.
Calculate your exact New Zealand net take-home pay under Inland Revenue (IRD) 2025/2026 tax brackets, ACC Earner's Levy (1.60%), KiwiSaver, IETC credit, and Student Loan deductions.