GST invoicing requirements NZ 2026: the complete guide

New Zealand's GST rules haven't changed dramatically in recent years, but compliance expectations have tightened as IRD invests more in data analytics and audit capability. This guide covers every requirement your invoices must meet in 2026 — and what happens if they don't.

GST registration: when it becomes mandatory

GST registration is mandatory when your taxable supplies exceed $60,000 in any 12-month period (looking back or projecting forward). Taxable supplies include most goods and services sold in NZ — there are exemptions for financial services, residential rent, and a handful of other categories.

Once you cross the threshold, you must register within 21 days. Late registration means you're personally liable for the GST you should have collected from the date you should have registered — not from the date you actually registered.

The three types of invoices under NZ GST law

IRD recognises different invoice standards based on transaction value:

Simplified invoice (under $50 GST inclusive): A receipt is sufficient. Must show: supplier name, GST number, date, description, and GST-inclusive price (with a statement that GST is included at 15%).

Tax invoice ($50–$999.99 GST inclusive): The full tax invoice requirements apply — see below.

Full tax invoice ($1,000+ GST inclusive): All tax invoice requirements plus the buyer's name and address.

Mandatory fields on a tax invoice

Every NZ tax invoice must contain all of the following:

1. The words "Tax Invoice" 2. Supplier's name (legal name or registered trading name) 3. Supplier's GST registration number in XXX-XXX-XXX format 4. Date of issue 5. Description of the supply — specific enough to identify what was provided 6. Quantity or volume of goods/services (required for invoices over $1,000) 7. Buyer's name and address (required for invoices over $1,000) 8. GST amount charged, OR a statement that the price includes GST 9. Total amount payable 10. Unique invoice number (not legally required under GST Act but required under income tax record-keeping rules)

What counts as a valid GST number?

Your NZ GST registration number is the same as your IRD number. It's issued when you register for GST through myIR. Format: XXX-XXX-XXX (9 digits, hyphenated).

You must display it on every tax invoice. If you display it incorrectly or display a number that doesn't belong to you, the invoice is non-compliant and your clients cannot claim GST on it.

Filing frequency and GST periods

NZ businesses file GST returns either monthly, two-monthly, or six-monthly:

Monthly — required if your annual taxable supplies exceed $24 million. Optional otherwise. Best for businesses with volatile cash flow or regular refunds.

Two-monthly — the default for most businesses. Returns are due by the 28th of the month following the end of each two-month period.

Six-monthly — available if your annual taxable supplies are under $500,000. Simplest for small operators.

Your filing frequency is set when you register. To change it, apply through myIR.

Invoice basis vs payments basis

Invoice basis (default): GST is owed in the period the invoice is issued, regardless of when you're paid. This means you may owe GST on invoices your clients haven't paid yet. Applies to all businesses.

Payments basis: GST is only owed when you actually receive payment. Available only to businesses with annual taxable supplies under $2 million. Requires an election in myIR.

Record-keeping requirements

GST records must be kept for 7 years from the end of the income year they relate to. Records must be: - Kept in English or in a form that IRD can read - Available for inspection by IRD within a reasonable time - Accurate and complete

Digital records are fully acceptable. Scanned copies of paper receipts are fine. Cloud storage (including PayWren) satisfies the accessibility requirement.

Common GST compliance failures in 2026

Based on IRD's published audit focus areas, these are the most common issues:

Claiming GST on non-deductible expenses — entertainment at 50%, private use of assets, and residential accommodation are not fully GST-claimable.

Failure to return GST on associated party transactions — if you supply goods/services to a related party below market value, GST is based on open market value.

Missing or incorrect GST numbers on invoices — increasingly flagged through IRD's data-matching systems.

Incorrect treatment of zero-rated supplies — exported goods and services are zero-rated (0% GST), not GST-free. The distinction matters for your GST return.