NZ Provisional Tax Estimator 2025-26

What Is Provisional Tax in New Zealand?

Provisional tax is advance payment of income tax for people whose residual income tax (RIT) exceeds $5,000. RIT is the amount of tax you owe after subtracting PAYE and other withholding taxes from your total income tax liability. It applies to self-employed individuals, business owners, property investors, and anyone with significant income that is not taxed at source. Unlike PAYE employees who have tax deducted automatically each pay period, provisional taxpayers must proactively estimate and pay their tax across the year in three instalments. Provisional tax is not an additional tax — it is simply a prepayment system to spread the tax burden and prevent large lump-sum bills. Based on IRD guidance, rates effective for the 2025-26 tax year (1 April 2025 to 31 March 2026).

Three Provisional Tax Methods Compared

The standard uplift method requires you to pay 105% of your prior year's RIT in three equal instalments. It is simple, safe from use-of-money interest (UOMI), and requires no forecasting. The estimation method allows you to base payments on your current-year income estimate — useful if income has dropped, but exposes you to UOMI if you underestimate. The ratio method calculates instalments as a percentage of your GST-exclusive taxable supplies, based on your prior year's ratio of tax to supplies — ideal for businesses with GST filing cycles already in place. A fourth method, AIM (Accounting Income Method), is available for businesses under $5 million turnover using approved accounting software and avoids UOMI entirely when used correctly.

Payment Dates and UOMI for 2025-26

For standard balance-date (31 March) taxpayers, the three provisional tax instalment dates are 28 August 2025, 15 January 2026, and 7 May 2026. Paying late or underpaying triggers use-of-money interest at 10.39% per annum from the day after each due date. IRD also charges late payment penalties of 1% on the day after the due date and a further 4% if still unpaid seven days later. If you pay the correct standard uplift amount on each due date, UOMI does not apply even if your actual tax turns out to be higher — this is the key protection the standard uplift method provides.

How to Calculate Your Residual Income Tax (RIT)

Your RIT is your total income tax liability minus PAYE deducted by your employer, minus any RWT already withheld at source. For a self-employed contractor earning $90,000 with no PAYE, the income tax liability is approximately $22,420 at 2025-26 PAYE rates. Subtract $0 in PAYE deductions and $0 in RWT — RIT equals $22,420. Because this exceeds $5,000, provisional tax applies. The standard uplift for the following year would be $22,420 × 105% = $23,541, paid in three instalments of $7,847. Use the NZ Income Tax Calculator in this hub to estimate your income tax liability before applying the uplift formula.