If you run a business in New Zealand, provisional tax is simply a way of paying your expected income tax progressively during the year rather than facing one large bill later.
In most cases, you will become liable for provisional tax in NZ if your residual income tax from your previous income tax return was more than $5,000. Residual income tax, often shortened to RIT, is broadly the income tax you still have to pay after deducting tax credits such as PAYE. Inland Revenue confirms that the $5,000 threshold remains current.
At Humphries Associates, we find the difficult part is usually not understanding what provisional tax is. It is working out how much to pay, which calculation method makes sense, when the provisional tax due dates fall, and how those payments affect business cash flow.
Information and thresholds in this guide were checked against Inland Revenue guidance on 2 September 2026. Tax rules can change, and the correct treatment will depend on your circumstances.
Quick answer
For most New Zealand businesses with a standard 31 March balance date, provisional tax calculated under the standard or estimation option is generally paid in three instalments:
| Instalment | General due date |
| First | 28 August |
| Second | 15 January |
| Third | 7 May |
These are the current general dates for taxpayers using the standard or estimation option. Different dates can apply if you have a non-standard balance date, file GST six-monthly, use the ratio option or use the Accounting Income Method (AIM).
You normally do not need to decide whether provisional tax applies from scratch. Once your tax return has been prepared, your residual income tax helps determine whether you fall into the provisional tax system.
If you would like us to prepare your return and help manage the resulting tax obligations, our Tax Return Services cover income tax preparation, filing and tax payment planning.
What this means for a New Zealand business
Provisional tax is not an additional tax.
It is essentially income tax paid in advance towards the tax bill for the current financial year.
For example, imagine we prepare your business accounts and your previous year’s tax return shows residual income tax of $30,000. Because this is above $5,000, provisional tax will generally apply in the following year.
Instead of waiting until the end of that following year and paying the entire amount at once, you make provisional tax payments during the year.
This is important for cash-flow planning.
One of the biggest provisional tax problems we see is a profitable business treating the money sitting in its bank account as available working capital without allowing for tax. When an instalment date arrives, the business may suddenly need to find thousands of dollars.
The issue can be even more noticeable for a newer business.
Inland Revenue explains that businesses using the standard, estimation or ratio options generally do not have to pay provisional tax during their first year of business. However, the first year is not tax free. Income tax from that first year still becomes payable, and provisional tax for the second year can begin around the same period.
That can create a significant cash requirement if it has not been planned for.
How it works step by step
There are four main ways Inland Revenue allows provisional tax to be calculated:
- Standard option
- Estimation option
- Accounting Income Method (AIM)
- Ratio option
Inland Revenue uses the standard option unless another method is chosen.
1. Standard option
The standard option works well where income and profitability are reasonably consistent.
Your provisional tax is generally calculated using:
- the previous year’s residual income tax plus 5%, or
- residual income tax from two years earlier plus 10% in particular filing situations.
Which uplift applies depends partly on when the previous year’s return was filed.
For example, if your previous year’s RIT was $30,000, and the 105% calculation applies:
$30,000 × 105% = $31,500 provisional tax
For a standard 31 March balance date with three equal instalments:
$31,500 ÷ 3 = $10,500 per instalment
That would generally mean payments of $10,500 on 28 August, 15 January and 7 May.
This is a simplified example. Your actual payment position can vary depending on your filing date, GST filing frequency and tax circumstances.
2. Estimation option
Sometimes last year’s results are not a good indication of what will happen this year.
Perhaps you have:
- lost a major customer
- won a large contract
- sold part of the business
- experienced unusually high growth
- reduced your working hours
- changed how you earn your income.
The estimation option allows provisional tax to be based on what you expect your actual residual income tax to be.
This can help reduce unnecessary overpayments when income falls, but estimating too low can expose you to interest and potentially penalties. Inland Revenue allows estimates to be revised up to the final provisional tax instalment date.
We therefore recommend monitoring your actual results against your estimate throughout the year rather than setting an estimate and forgetting about it.
3. Accounting Income Method, or AIM
The AIM method in NZ takes a different approach.
Instead of relying mainly on last year’s tax position, AIM uses information from your accounting software to calculate provisional tax based more closely on the business’s current financial performance.
Inland Revenue says AIM may be available to individuals and companies that use accounting software and have annual turnover of less than $5 million.
AIM can be particularly useful where a business:
- is growing quickly
- is relatively new
- has seasonal income
- has irregular profits
- has experienced a significant reduction in income
- finds forecasting difficult.
Under AIM, provisional tax is generally paid only when the business is making a profit, and payments are aligned with the relevant filing cycle.
4. Ratio option
The ratio option links provisional tax payments more closely with GST taxable supplies.
It can suit some seasonal businesses because payments can move with turnover rather than being based entirely on fixed instalments.
There are eligibility requirements, including GST filing requirements and residual income tax limits, so we normally look at the business circumstances before determining whether this approach is appropriate.
Calculations, records or decisions involved
Good provisional tax management starts with good financial information.
When we review a client’s provisional tax position, we may need information such as:
- your previous income tax return
- previous residual income tax
- current year-to-date profit and loss reports
- balance sheet information
- up-to-date bank reconciliations
- GST returns
- expected income for the remainder of the year
- significant upcoming expenses
- changes in shareholder salaries
- changes in business ownership or structure
- expected one-off income or gains
- information about tax already deducted or paid.
We are not only interested in what happened last year.
We want to understand what is happening now.
Suppose your previous year’s RIT suggests provisional tax of $40,000, but your largest customer has recently left and you expect profit to fall substantially. Simply paying the standard calculation without reviewing the current position could potentially tie up cash unnecessarily.
The opposite can also happen.
If your business is growing strongly and this year’s profit is well above last year’s, relying solely on last year’s figures may leave you with additional tax to pay once the final return is prepared.
This is why accurate accounting records are valuable beyond compliance. They help us make better tax and cash-flow decisions during the year.
Common mistakes and risks
Forgetting that provisional tax is income tax
Some business owners think provisional tax is an additional IRD charge.
It is not. It is a way of paying income tax throughout the year.
Missing provisional tax due dates
For most taxpayers using the standard or estimation option with a 31 March balance date, the key dates are 28 August, 15 January and 7 May. These dates were checked against Inland Revenue guidance on 2 September 2026.
Your dates may differ depending on your balance date and calculation method.
Assuming last year’s profit will repeat
Businesses change.
A major new customer, loss of a contract, staffing changes, rising costs or a large one-off transaction can make last year’s tax position a poor guide to this year’s result.
Underestimating without monitoring the result
Estimating provisional tax downwards may improve short-term cash flow, but an estimate that turns out to be too low can create interest exposure and a larger balancing payment later.
Failing to plan for the first major tax year
The transition from your first year in business into your second can create a difficult period because terminal tax from year one and provisional tax relating to year two may need to be funded around similar periods.
We encourage new business owners to start setting tax money aside before the first major bill arrives.
Ignoring a missed payment
If you miss an instalment, do not simply wait until the next tax return.
Late or insufficient payments can result in interest or penalties depending on your circumstances. Inland Revenue also recognises tax pooling as one way eligible taxpayers may manage provisional tax payments.
We have also explained how this works in our existing Tax Pooling guide.
Practical checklist
If provisional tax applies to your business, we recommend working through this checklist:
- Confirm whether your previous residual income tax exceeded $5,000
- Check which provisional tax calculation method you are using
- Confirm your actual payment dates in myIR
- Make sure your accounting records and bank reconciliations are up to date
- Compare current profitability with the previous year
- Identify large changes in income, expenses or business structure
- Forecast cash available around each provisional tax date
- Put tax money aside rather than treating it as available operating cash
- Review your position before each instalment
- Revisit an estimate if the business is performing differently from forecast
- Speak with your accountant early if you expect difficulty making a payment
- Keep records showing how estimates and tax decisions were calculated
We would much rather review a developing tax issue early than try to solve it after a payment has already been missed.
When to speak with an accountant or business adviser
Provisional tax can be straightforward when a business has predictable earnings, accurate records and stable cash flow.
Professional advice becomes more valuable when something changes.
We recommend speaking with us if:
- this is your first or second year in business
- your profit has increased significantly
- revenue or profit has fallen
- you have seasonal or unpredictable income
- you are considering changing provisional tax methods
- you are unsure whether AIM would suit your business
- you expect a large one-off transaction
- your records are behind
- you have missed an IRD payment
- you are concerned about cash flow around upcoming tax dates.
At Humphries Associates, we can look at provisional tax as part of the wider tax position rather than considering one instalment in isolation.
That can include reviewing the income tax return, current financial results, cash-flow expectations and the timing of upcoming obligations.
You can learn more about how we prepare and manage income tax obligations through our Tax Return Services.
If you would like us to review your provisional tax position, contact Humphries Associates before the next payment date so we have time to assess the numbers properly.
Frequently Asked Questions
What is the short answer for a New Zealand business?
Provisional tax allows a New Zealand business to pay expected income tax progressively during the year. You will generally need to pay provisional tax if your residual income tax from your previous return was more than $5,000. The amount and payment dates depend on the calculation method you use and your circumstances.
What records or information will I need?
We generally need your previous tax information and accurate current accounting records. This can include your previous residual income tax, profit and loss reports, balance sheet, bank reconciliations, GST information and forecasts for the remainder of the year. Major changes to income, expenses or business structure should also be considered.
What are the most common mistakes?
Common mistakes include missing provisional tax due dates, failing to set cash aside, assuming last year’s result will repeat, underestimating tax without regularly reviewing the estimate, and failing to seek help after a payment has been missed.
When should I get professional advice?
We recommend getting advice when your income or profitability changes significantly, you are entering your first provisional tax year, you are considering AIM or another calculation option, you have irregular cash flow, or you expect difficulty meeting a payment. The earlier we can review the position, the more options we generally have available.
Important: This article provides general information about provisional tax in New Zealand. It is not individual tax, financial or legal advice. The appropriate provisional tax treatment depends on your business structure, income, filing history, balance date and other circumstances.