What needs to be on my first tax invoice — and what's just convention?

What to watch for

Six things to actually check — most of which your software either handles automatically or has a setting for.

1. The "TAX INVOICE" header is convention, not law. The term in the Act is "taxable supply information", and you're not required to put the words "TAX INVOICE" anywhere on the document.² Your invoice can say "Invoice", "Statement", "Account", or carry no heading at all. Most accounting tools still produce "Tax Invoice" headers because the templates haven't been refreshed; that's fine — it's harmless inertia, not a compliance issue. If you're customising a template and the in-caps "TAX INVOICE" feels old-fashioned, you can drop it.

2. Your software almost certainly defaults to the over-$1,000 format for every invoice. Which is fine. The law has three tiers — under $200 (no TSI required at all, just records of the transaction), $200–$1,000 (simplified TSI: supplier name, GST number, date, description, GST-inclusive amount), and over $1,000 (all of the above plus the recipient's name and address).³ Defaulting to the over-$1,000 format for everything over-delivers but doesn't hurt anyone — your $300 invoice can carry the recipient's address; that's not a problem. The failure mode worth knowing about is the reverse: if your tool is somehow producing under-delivered invoices on larger jobs (no description, no recipient details on a $5,000 invoice), that's the customer's GST-credit-claim risk turning into your problem. Spot-check a recent invoice over $1,000 to confirm your tool is including recipient name and address.

3. The software can't tell whether you're GST-registered. Check the toggle before sending. This is the most-often-broken rule and it's not a formatting problem. If you're not registered for GST — under the $60,000 threshold and not voluntarily registered — your invoices must not charge GST or display a GST number. Most accounting tools ask you to set your GST status during setup; if you ticked "yes" before you actually registered (or kept it on after deregistering), the tool will keep adding 15% to your invoices. That's collecting tax you can't legally remit, and it's a real problem if it surfaces in an audit or a customer dispute. Worth a five-minute check in your settings before you send the first invoice. Cross-link: see the entry on GST registration for whether you should be registered in the first place.

4. The 28-day rule starts from a request, not from the date of supply. A GST-registered customer can request taxable supply information from you, and you have 28 days from the date of the request to provide it. The obligation sits in sections 19K and 19L of the GST Act, and failing to provide the information within that window when it’s required is an offence under section 143.⁴ In practice you're issuing the TSI at invoice time, so this almost never bites — but the structural reason it matters is that your records have to be retrievable. If a customer comes back six months or a year later asking for a copy of an old invoice, you need to be able to find it. Accounting software handles retrieval automatically; if you're running on a spreadsheet and emailed PDFs, you need a system. The 28-day clock starts from the request, not from when you get around to it.

5. Invoice numbering is convention, not law — but it earns its place when you change systems. Sequential invoice numbers aren't required by the Act. Your software is sequencing them automatically; you don't have to think about it. The watch-out is what happens when you switch tools — moving from a spreadsheet to a proper accounting platform, or from one platform to another. The new system will start fresh from 1 (or whatever you set); your old numbers stay where they are. Don't let the gap between systems create a numbering gap that looks like a missing invoice. If you're voiding invoices, void them in the system rather than just deleting them — voids leave a trail; deletions don't, and gaps in a sequence look suspicious in an audit context.

6. "Payment terms" and "due date" aren't legal requirements — they're commercial choices. Nothing in the Act says when an invoice has to be paid. Your contractual terms with the customer set that. Most accounting tools have a default — "Net 7", "Net 20", "20th of the month following" — set somewhere in your settings. The watch-out: relative phrasing ("due in 7 days") is dramatically less effective than a specific date ("due 31 May 2026") at getting paid on time. If your tool is using relative phrasing by default, see if you can change the setting to display the actual calculated due date. Specificity sets expectations the customer can plan against; relative phrasing turns into ambiguity.

A separate point on the relationship between your software and the law. The accounting tool is a vehicle, not a guarantee. It produces output that will almost always be compliant, but the responsibility for whether the output is right sits with you — particularly on the things the software can't infer (your GST status, whether you're issuing to the right entity, whether the description is accurate enough that the customer can claim their GST credit). The rules deliberately give businesses flexibility on packaging — you can provide taxable supply information in an email, an invoice, an exchange via accounting software, or any combination — recognising that real businesses run on tools, not on paperwork. What matters is that the same information is available; how you package it is up to you. If you're using a modern accounting or POS tool, your job is to know what good output looks like and spot-check that it's producing it. If you're hand-rolling an invoice for a one-off — the first invoice before you've set up software, a one-off from a personal email, a side-hustle that hasn't graduated to a tool — the same rules apply but you're carrying the formatting responsibility yourself.

Where this entry stops

This entry covers what's required vs convention for a standard NZ tax invoice, GST-registered or not, software-produced or hand-rolled. It doesn't cover:

• Claiming back GST on your inputs. Input tax credits, what counts as a deductible business expense, and the records you need on the receiving side of transactions — different rules, different framework. Routes to your accountant and to IRD's input-tax-credit guidance.
• The decision about whether to register for GST in the first place. Different question with its own trade-offs (voluntary registration considerations, filing-frequency choices, accounting-basis choices). See the entry on GST registration.
• Buyer-created tax invoices. A specific arrangement where the customer issues the invoice rather than the supplier — common in some industries (livestock, scrap metal, primary produce). The April 2023 rules removed the IRD-approval requirement that used to apply, but the mechanics are still specific and warrant their own treatment. Routes to IRD or your accountant.
• Cross-border invoicing. International sales, GST on imported services, distantly-taxable goods, the offshore-supplier rules — all separate frameworks. Specialist territory.
• E-invoicing via Peppol. The technical standard for structured electronic invoicing — not required, but increasingly common between larger trading partners and a near-default for invoices to government agencies. Worth knowing about; worth not over-engineering at first-invoice stage.

If you're invoicing government agencies or large corporates with formal procurement processes, they'll often have their own format requirements layered on top of the legal minimum (purchase order numbers, line-item references, specific payment-terms wording). Meet their format and you'll meet the GST rules automatically. If you're chasing an unpaid invoice, that's a separate problem with its own playbook. And if your software is doing something you're not sure about — or if you're carrying the formatting yourself and want a second pair of eyes on a template — half an hour with an accountant is meaningfully cheaper than a wrong call that compounds across a year of invoices.

A correctly formed invoice is one a registered customer can act on the day it lands — they claim their input tax credit, AP doesn't bounce it, "due 31 May" gets paid where "due in 7 days" gets filed. Build the template once; every invoice after is faster out and faster back as cash. Get it wrong and you're re-issuing, chasing, and explaining the same things on every sale.

Last verified 27 May 2026 against the Goods and Services Tax Act 1985 sections 19E to 19Q at legislation.govt.nz, cross-checked against current commentary from PwC, Grant Thornton, and NZ accounting practitioners on the April 2023 changes. Full source list: references. The taxable-supply-information rules have been stable since 1 April 2023; this entry's framing is unlikely to drift unless the underlying thresholds change.