GST due dates and a cash buffer plan that actually works

GST is one of the most common reasons New Zealand businesses end up needing money in a hurry. Not because it’s unexpected — the dates are published years ahead — but because GST money arrives mixed in with everything else. It sits in the trading account looking like profit, gets spent on wages and suppliers, and then the return falls due. This guide sets out the dates, explains how your filing frequency shapes the problem, and gives you a set-aside method simple enough to actually keep doing.

What are the GST basics in 2026?

According to Inland Revenue:

• Rate: GST is charged at 15%.
• Registration: you must register if your turnover was at least $60,000 in the last 12 months, or you expect it will be in the next 12 months.
• Returns: you file a return for each taxable period and pay any GST owing.

The GST portion of a GST-inclusive price is 3/23 of the total. So of every $115 a customer pays, $15 belongs to Inland Revenue (if you’re registered and the sale is standard-rated).

When is GST due?

In most taxable periods, both filing and payment fall on the 28th day of the following month. Inland Revenue’s key dates show the pattern — for example, the period ending 30 September is due 28 October. Two periods are different every year:

Period ends	Due
30 November	15 January
31 March	7 May
Most other periods	Usually the 28th of the following month — check myIR

The January and May dates exist because of the summer holidays and the end of the standard tax year. Both catch businesses out. The 15 January date lands just as many owners are coming back from a summer break with low takings — see our summer shutdown guide.

If a deadline lands on a Saturday, Sunday or public holiday, it generally shifts to the next working day. Always confirm the exact date in myIR.

Which filing frequency suits my cash flow?

Inland Revenue offers three main frequencies, depending on turnover:

Frequency	Available when
Monthly	Required if sales exceed $24 million in 12 months; available to others
Two-monthly	Sales under $24 million
Six-monthly	Sales under $500,000

Inland Revenue also says your GST filing frequency must align with your income tax balance date.

Each choice has a cash-flow personality:

• Monthly means small, frequent payments. Less time for GST to be accidentally spent — but more admin.
• Two-monthly is the most common middle ground.
• Six-monthly means less admin but large, infrequent payments. If you’re not disciplined about setting money aside, a six-monthly bill can be a shock.

If GST crunches keep happening, moving to a more frequent filing cycle can help. It shrinks each payment and shortens the time money sits around tempting you. You can change frequency in myIR when your circumstances change.

What’s the simplest set-aside method?

The method that works for most small businesses is boring, which is why it works:

1. Open a separate account — call it “GST and tax”. Some banks let you name sub-accounts.
2. Pick a transfer day — every Monday, for example.
3. Move 3/23 of last week’s GST-inclusive takings into the GST account. If your sales are mostly standard-rated, that’s simple. If you want to net off GST on expenses, move a bit less — but err on the side of more.
4. Don’t touch it except to pay Inland Revenue.
5. Reconcile when you file. Any surplus can come back to trading or stay as a tax buffer.

Your accounting software can show your GST position in real time, which makes step 3 easy. Some owners automate the transfer with a weekly automatic payment.

What should I do if a GST payment is already looming and I’m short?

First, file the return on time even if you can’t pay in full — an unfiled return is worse than an unpaid one. Then:

• Check what’s genuinely owed in myIR.
• Contact Inland Revenue or apply for an instalment arrangement in myIR. Inland Revenue notes it charges interest on overdue amounts and includes it in instalments.
• Consider funding if an arrangement doesn’t fit, or if Inland Revenue has escalated. A business loan to pay IRD can clear the balance in one payment, often directly to Inland Revenue.

Inland Revenue has been increasingly active on overdue GST and employer debt through 2025 and 2026, so a GST balance that’s left to grow is more likely to attract collection action than it once was.

If you’d like to talk it through, start a quick enquiry — there’s no credit check to enquire.

How does a line of credit fit with GST?

A business line of credit is not a substitute for setting GST aside, but it’s a useful safety net. If a GST payment falls in a quiet week — January is the classic — you can draw on the line, pay on time and repay as sales recover. The key is to treat it as a timing bridge, not as the place your GST money lives.

What about provisional tax?

GST isn’t the only tax with fixed dates. If your residual income tax was more than $5,000 last year, provisional tax instalments also apply. Our provisional tax guide shows how to line those up with GST so they don’t collide.

What about GST refunds after a big purchase?

GST works in both directions. If you buy a large piece of equipment or fit out new premises, the GST you paid may exceed the GST you collected in that period, and you may be due a refund once your return is processed. That’s helpful, but it creates its own timing gap: you pay the full GST-inclusive price today and receive the GST back later. Plan for it. Some owners choose a shorter filing period around a major purchase so the refund comes back sooner — talk to your accountant about whether that suits you. And if a supplier deposit or equipment purchase needs funding in the meantime, factor the expected refund into your repayment plan rather than counting it as spare cash.

What are the common GST cash mistakes?

• Treating the whole bank balance as spendable. Part of it is Inland Revenue’s.
• Choosing six-monthly filing without a set-aside habit.
• Forgetting the 15 January date when planning summer holidays.
• Leaving returns unfiled because the money isn’t there.
• Not reviewing filing frequency after the business grows.

Illustrative example: a Wellington cafe changes its rhythm

This example is illustrative only. A Wellington cafe files six-monthly and keeps getting caught by its GST bill, borrowing short-term twice in a year to pay it. The owner switches to two-monthly filing, opens a separate GST account and sets a Monday automatic payment equal to an estimate of the week’s GST. Within six months, every GST payment is made from the GST account with a small surplus left over. The occasional quiet-week gap is covered by a modest line of credit, drawn and repaid within weeks.

How do I put this into practice this week?

• Find your next GST due date in myIR and put it in your calendar with a reminder ten days before.
• Open a separate GST account if you don’t have one.
• Set a weekly transfer, even a rough one.
• Check whether your filing frequency still suits the business.
• Add your myIR GST summary to your funding readiness pack.

When a GST bill is bigger than the bank balance

It happens to well-run businesses, especially after a slow season or a period of growth. If a GST payment is coming and the money isn’t there, a short, accurate enquiry is the quickest way to see your options. It takes about a minute and there’s no credit check when you first enquire. We don’t push your details out to a crowd of lenders — one team reads them, and a real person calls you with options that fit your situation. Please tell us the real GST figure from myIR so we can match you properly the first time.

See if you qualify →