If you run a GST-registered business in New Zealand, filing your GST return correctly is one of those jobs that can look straightforward until a missing invoice, incorrect accounting period or unusual transaction changes the numbers.
When we work through a GST return in NZ, we’re not simply looking at how much GST has been collected and subtracting GST paid on expenses. We also need to make sure the business is using the correct accounting basis, transactions are in the right taxable period, GST has only been claimed where appropriate, and any adjustments have been dealt with correctly.
Information and rules in this guide were checked against Inland Revenue guidance on 2 September 2026. Tax rules can change, so current IRD guidance should always be checked before relying on a rate, threshold or filing deadline.
Quick answer
If your business is registered for GST, you generally need to file a GST return for every taxable period, including periods where there is no GST to pay or claim.
Inland Revenue states that a GST return is normally due on the 28th of the month following the end of the taxable period. There are two important exceptions:
- A period ending 31 March is due by 7 May.
- A period ending 30 November is due by 15 January.
Your GST payment is generally due on the same day as the return. If a due date falls on a weekend or public holiday, the next working day normally applies.
The return can usually be filed through myIR or directly from compatible accounting software. Inland Revenue requires information covering sales and income, purchases and expenses, and any relevant debit or credit adjustments.
One of the most important things we tell business owners is not to treat a GST return as an isolated compliance exercise. The numbers should reconcile with your bookkeeping, bank accounts and accounting records.
What this means for a New Zealand business
How often you need to file a GST return depends on your GST filing frequency.
As at September 2026, Inland Revenue provides three main filing frequencies:
| Filing frequency | General eligibility |
| Monthly | Available to anyone and compulsory where sales exceed $24 million in a 12-month period |
| Two-monthly | Available where sales are under $24 million in a 12-month period |
| Six-monthly | Available where sales are under $500,000 in a 12-month period |
Many smaller businesses use two-monthly filing, although the right frequency depends on the size and nature of the business. Businesses regularly receiving GST refunds may prefer monthly filing, while a very small business with relatively few transactions may qualify for six-monthly filing.
Your accounting basis is equally important.
Under the payments basis, GST is generally recognised when you receive payment from customers or pay suppliers. This basis is generally available where total sales are $2 million or less over the relevant 12-month period.
Under the invoice basis, GST can become reportable when an invoice is issued or received even though the money may not yet have changed hands.
A hybrid basis is also available, although Inland Revenue notes that it is not commonly used by small businesses.
Using the wrong basis when preparing a return can move income or expenses into the wrong GST period and produce an incorrect result.
If you are not yet registered, we recommend first reading our guide to GST registration in New Zealand so you understand when registration is required and how your GST obligations begin.
How it works step by step
When we prepare or review a GST return, we generally work through the following process.
1. Confirm the taxable period
First, we make sure we know exactly which dates the GST return covers.
This sounds obvious, but transactions around the beginning or end of a GST period are a common source of errors.
2. Confirm the accounting basis
We check whether the business uses the payments, invoice or hybrid basis.
This determines when transactions need to be recognised.
For example, imagine a customer is invoiced for $11,500 including GST on 25 August, but they do not pay until 10 September.
Under the invoice basis, that transaction may need to be accounted for when invoiced.
Under the payments basis, the timing will generally follow when the payment is received.
3. Reconcile sales and income
We check that the sales figures agree with the accounting system and, where appropriate, bank records.
We also look for transactions that may need different GST treatment, including zero-rated or exempt supplies.
4. Review purchases and expenses
Next, we review business expenses where GST is being claimed.
The key word here is business.
Just because money has left a business bank account does not automatically mean GST can be claimed.
We need to consider whether the purchase relates to the taxable activity and whether appropriate supporting information is held.
5. Check adjustments
Some GST returns require debit or credit adjustments.
These can arise from matters such as corrections, bad debts, changes in how an asset is used or other situations where the normal sale-and-purchase calculation does not tell the whole story.
6. Review the return before filing
Before we submit a return, we compare it against previous periods and ask whether the result makes commercial sense.
A sudden large GST refund or unexpectedly high GST payment is not automatically wrong, but it is a reason to investigate the underlying transactions before filing.
7. File and arrange payment
The completed return can usually be submitted through myIR or supported accounting software.
If GST is payable, we make sure the payment deadline is recorded as well as the filing deadline.
Calculations, records or decisions involved
The standard GST rate on most taxable goods and services in New Zealand is 15% as at September 2026.
When a price already includes GST, the GST component can generally be calculated using 3/23 of the GST-inclusive amount.
For example:
GST-inclusive sales: $11,500
GST component: $11,500 × 3 ÷ 23 = $1,500
Assume the business also has eligible GST-inclusive expenses of $4,600:
GST component of expenses: $4,600 × 3 ÷ 23 = $600
In this simplified example:
GST collected: $1,500
Less GST claimed: $600
GST payable: $900
Real GST returns can be considerably more complicated because of adjustments, private use, assets, zero-rated supplies, exempt income and timing differences.
What records do I need?
Good record keeping makes GST filing much easier.
Inland Revenue states that businesses must generally keep records of cash and electronic sales and purchases for seven years. These can include:
- taxable supply information
- supply correction information
- invoices and receipts
- bank statements
- credit card records
- cashbook records
- point-of-sale records.
Since 1 April 2023, New Zealand has used the broader concept of taxable supply information rather than relying solely on the old requirement for a traditional “tax invoice”. The information retained must still support the amounts included in the GST return.
Humphries Associates already has a useful guide explaining the changes to GST record keeping.
Common mistakes and risks
The GST mistakes we see are often less about complicated tax law and more about inconsistent processes.
Filing in the wrong period
An invoice or payment is sometimes included based on when somebody notices it rather than according to the business’s GST accounting basis.
Claiming GST on expenses without sufficient support
GST claims need to be supported by appropriate taxable supply information.
A bank transaction by itself does not necessarily establish that the GST claim is correct.
Mixing personal and business expenditure
Private expenditure can easily find its way into accounting software, particularly where the same card or bank account is being used for both purposes.
Missing adjustments
Assets, bad debts, private use and unusual transactions can create GST adjustments that normal bookkeeping may not automatically identify.
Treating all income the same
Not every dollar received necessarily has the same GST treatment. Some supplies may be zero-rated or exempt.
Forgetting a nil return
A return still needs to be filed for every taxable period even where there is no GST activity.
Filing or paying late
This is particularly avoidable.
As at September 2026, Inland Revenue says the GST late-filing penalty is $50 for businesses using the payments basis and $250 for businesses using the invoice or hybrid basis. Late payments can also attract penalties and interest.
Ignoring a mistake after filing
If an error is discovered, do not simply hope it disappears in the next period.
Inland Revenue provides several ways to correct genuine GST return errors, depending on the circumstances and size of the error. These can include amending the original return through myIR, making an eligible correction in a later return, or asking Inland Revenue to make a change.
If the issue is significant or you are unsure which correction method applies, get advice before changing the numbers.
Practical checklist
Before filing a GST return, we recommend checking:
- Am I using the correct GST taxable period?
- Is my accounting basis payments, invoice or hybrid?
- Have all sales for the period been included?
- Have my bank accounts and accounting records been reconciled?
- Are GST claims supported by appropriate records?
- Have I removed private or non-business expenses where required?
- Have zero-rated or exempt transactions been treated correctly?
- Are there any unusual transactions or asset purchases?
- Are debit or credit adjustments required?
- Does the final GST amount look reasonable compared with previous periods?
- Have I checked the current filing and payment date?
- Have I kept copies of the records supporting the return?
The more consistently you complete these checks during the year, the easier each GST filing becomes.
When to speak with an accountant or business adviser
Some GST returns are perfectly manageable through good bookkeeping software and a consistent process.
We would recommend getting professional advice when:
- the business has fallen behind with GST returns
- records are incomplete or unreconciled
- there is uncertainty about the correct GST accounting basis
- a major asset has been bought or sold
- business assets are also being used privately
- the business has property-related transactions
- there are unusual, zero-rated or exempt supplies
- a previously filed GST return contains a material mistake
- the business has received an IRD query, review or audit request
- GST payments are creating significant cash-flow pressure.
GST obligations can also interact with other taxes. For example, businesses paying provisional tax may need to consider how their GST periods align with their balance date. Our guide to provisional tax in New Zealand explains that system in more detail.
If you want help preparing and filing GST or other business tax returns, you can read about our Tax Return Services.
For questions about your own circumstances, contact Humphries Associates and talk with an accountant or business adviser.
Frequently Asked Questions
What is the short answer for a New Zealand business?
If you are registered for GST, you need to file GST returns for your taxable periods, including nil returns. Returns are generally due on the 28th of the following month, with special dates applying to periods ending 31 March and 30 November.
What records or information will I need?
You would normally expect to have complete sales and purchase records, bank and credit card transactions, taxable supply information, relevant invoices and receipts, details of adjustments and reconciled accounting records. Inland Revenue generally requires tax records to be retained for seven years.
What are the most common GST mistakes?
Common problems include using the wrong accounting period, claiming GST on ineligible expenses, mixing business and private expenditure, missing adjustments, incorrectly treating zero-rated or exempt income, failing to keep appropriate records and filing after the due date.
When should I get professional advice?
We recommend getting advice where there are unusual or high-value transactions, incomplete records, GST errors from previous periods, property or asset transactions, mixed business and private use, overdue returns, or uncertainty about how GST rules apply to your situation.
This article provides general information only. GST treatment depends on the facts of each transaction and the circumstances of the business. It should not be treated as personalised tax, accounting or financial advice.