GST.co.nz is New Zealand's most comprehensive free resource dedicated entirely to the Goods and Services Tax. With 20 purpose-built calculators and 10 in-depth guides, it covers every aspect of GST from basic add/remove calculations through to property transaction rules, penalty calculations, and audit risk assessment.
The site is built and maintained by James Graham, the founder of Calculate.co.nz, New Zealand's largest collection of free financial calculators. GST.co.nz was created because GST deserves its own dedicated platform: a single place where every GST question can be answered with a purpose-built tool and a clear, practitioner-written explanation.
Every calculator on this site is verified against the Goods and Services Tax Act 1985 and current Inland Revenue guidance. All rates and thresholds are updated for the 2026/27 tax year. The central configuration system means that when rates change, every calculator and guide on the site updates simultaneously from a single source of truth.
GST.co.nz is part of the Calculate.co.nz and Realtor.co.nz group. All tools are provided free of charge, with no paywalls, no sign-ups, and no premium tiers. If you need a GST tool, it's here.
If you'd like to connect, you can find James on LinkedIn.
If you've found a bug, or would like to contact us, or learn more about GST.co.nz.
GST.co.nz is part of the Calculate.co.nz group, New Zealand's largest collection of free financial calculators and tools. For PAYE, mortgage, KiwiSaver, and 200+ other calculators, visit Calculate.co.nz.
All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice. GST calculations should be verified against the Goods and Services Tax Act 1985 and current IRD guidance.
GST.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform.
All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.
© 2019 to 2026 GST.co.nz. All rights reserved.