Provisional Tax Calculator

Provisional tax is income tax paid in advance during the current year, based on your expected income. You must pay provisional tax when your residual income tax (RIT) from the previous year exceeds $5,000. RIT is the income tax you owe after subtracting any tax already withheld at source (such as PAYE or RWT). Self-employed people, investors, and business owners are the most common provisional taxpayers. If you are a new taxpayer and your RIT exceeds $5,000 in your first year, you may also be required to pay provisional tax the following year. Provisional tax is not a separate tax — it is simply a prepayment of your end-of-year income tax obligation, calculated using your chosen method (standard, estimation, or ratio). Paying provisional tax in instalments helps avoid a large lump-sum terminal tax bill in April. Source: IRD — Provisional Tax (ird.govt.nz/income-tax/provisional-tax).

For taxpayers with a standard 31 March balance date, there are three instalment dates under the standard uplift method: 28 August, 15 January, and 7 May. Each instalment is one-third of your total provisional tax liability for the year (based on 105% of your prior year RIT). If your balance date is different — for example, 30 June or 31 December — your instalment dates shift accordingly. Taxpayers using the estimation method must also pay by these dates but can adjust the amount based on their current-year estimate. The ratio method (available if you are GST-registered and file two-monthly) spreads payments differently, aligning provisional tax with your GST returns. Missing an instalment date triggers use-of-money interest (UOMI) on any shortfall. It is important to calendar these dates early to avoid penalties. Source: IRD — Provisional Tax (ird.govt.nz/income-tax/provisional-tax).

The standard uplift method is the most common way to calculate provisional tax in New Zealand. Under this method, your provisional tax for the year equals 105% of your prior year residual income tax (RIT). If you did not have a tax return in the year before that, IRD uses 110% of your RIT from two years ago. The ratio method — available to GST-registered taxpayers who file two-monthly GST returns — uses a fixed percentage applied to your GST taxable supplies; this percentage is based on your prior year RIT divided by your taxable supplies. The estimation method allows you to estimate your current-year income and calculate tax accordingly, but if you underestimate, use-of-money interest applies. Most taxpayers find the standard uplift method simplest, as it avoids the need to estimate income mid-year. Source: IRD — Provisional Tax Methods (ird.govt.nz/income-tax/provisional-tax).

If you underpay provisional tax in New Zealand, Inland Revenue charges use-of-money interest (UOMI) on the shortfall. As of 2025, the underpayment UOMI rate is approximately 10.9% per annum, compounding daily from the instalment due date to the date of payment. UOMI is not a penalty — it is simply interest charged for having the use of money that should have been paid to IRD. Penalties (late payment penalties of 1% then 4%) apply only if you miss a payment entirely and do not make arrangements. To avoid UOMI, you can use the safe-harbour rule: taxpayers with a prior-year RIT under $60,000 who pay the correct standard uplift instalments on time are protected from UOMI even if they end up owing more tax. Tax pooling is another option — IRD-approved intermediaries let you buy provisional tax credits from other taxpayers to cover shortfalls at lower rates. Source: IRD — Use-of-Money Interest (ird.govt.nz/income-tax/provisional-tax).