Editorial standards

People use Calculate.co.nz to make real financial decisions, so accuracy is the standard everything is held to. This page explains how our calculators and guides are built, sourced and checked.

Built from primary sources

Every calculator is built from scratch against primary New Zealand sources rather than copied from other websites. Depending on the tool, those sources include Inland Revenue (IRD), the relevant Acts and regulations, the Ministry of Business, Innovation and Employment (MBIE), the Ministry of Social Development (MSD), the Reserve Bank of New Zealand (RBNZ), Stats NZ and Waka Kotahi NZ Transport Agency. Where a figure comes from a specific rate or threshold, that source is the one we track.

Original work only

We never copy workings, content or wording from competitor sites. Each calculator's logic is implemented and tested independently from the underlying rules, and each guide is written in our own words. This protects accuracy and keeps the tools genuinely ours.

How accuracy is checked

• Each calculator is verified against a worked example so the formula and the published result agree.
• Rates, thresholds and rules are matched to the current tax year (currently 2026/27) and the source they come from.
• Shared figures live in central data files, so a rate is defined once and flows to every tool that uses it. This removes the risk of one calculator being updated while another is missed.
• Automated checks run across the library to catch broken logic, missing structured data or stale figures.

Plain language

Guides are written to be understood by anyone, without jargon walls or assumptions about prior knowledge. The aim is not only to give a number, but to help you understand it well enough to make the next decision yourself.

Independence and scope

Calculate.co.nz is independent and part of the Realtor.co.nz group. No bank, insurer or product provider decides what is built or what is shown. The tools are provided for education and as indicative estimates. They are not personalised financial, tax, legal or investment advice, and for significant decisions you should confirm the figures with Inland Revenue or a qualified professional.

Keeping data current

Rates and rules change, so sources are reviewed on a twice-monthly cycle and tools are updated when something changes. The full process is described in how we keep data current.

Corrections

If you find an error or something unclear, please tell us. Corrections are made promptly, and the change history of the library is recorded so maintenance is visible.

Maintained by James Graham. Last reviewed 2026-06-02.