Instalment schedule, the uplift method, safe-harbour rules, and UOMI, from the same engine PayWren runs for provisional taxpayers.
RIT threshold: $5,000 · Safe-harbour cap: $60,000 · UOMI: 10.88% p.a. · General information, not tax advice
Three instalments per year at offsets of 5, 9, and 13 months from the prior balance date. Two date exceptions apply: a December instalment moves to 15 January (holiday period); an April instalment moves to 7 May (terminal tax alignment).
Pay 105% of your previous year's residual income tax, split equally across instalments (ITA 2007 s RC 10). This is the standard path for most provisional taxpayers.
If you use RIT from the year before last (e.g. you have no prior-year figure), pay 110% of that amount. The extra 5% compensates for the older data (ITA 2007 s RC 10).
The annual uplift amount is split equally across the three instalments, with any rounding difference absorbed by the final payment.
You are not a provisional taxpayer. No instalments required.
Pay standard-method instalments on time: no UOMI regardless of actual tax outcome.
UOMI at 10.88% p.a. accrues if you underpay the uplift amount. TAA 1994 s 120KE.
Sources: ITA 2007 s RC 3 (threshold), TAA 1994 s 120KE (safe harbour cap), TAA 1994 s 120E (UOMI rate = 10.88% debit rate). Rates are verified 2026/27 fallbacks from lib/tax/provisional.ts.
You are a provisional taxpayer if your residual income tax (RIT), the tax still owing after all credits and PAYE, exceeds $5,000 in a tax year (ITA 2007 s RC 3). Most self-employed people earning over roughly $30,000 a year will be provisional taxpayers.
For a standard 31 March balance-date filer, the three instalment due dates are: 28 August (P1), 15 January (P2, shifted from 28 December due to the Christmas/New Year period), and 7 May (P3, shifted from 28 April to align with the terminal tax date). These are derived from offsets of 5, 9, and 13 months after the prior balance date.
The standard (uplift) method calculates provisional tax as a percentage of your previous year's RIT: 105% if using last year's RIT, or 110% if using the year before that. Paying the uplift amount on time keeps you in the safe harbour and protects you from use-of-money interest (UOMI). These rates come from ITA 2007 s RC 10.
If your RIT is $5,000 or less, you are not a provisional taxpayer at all. If your RIT is between $5,000 and $60,000, the safe harbour applies. Pay your standard-method instalments on time and no UOMI is charged. Above $60,000 RIT you are exposed to UOMI if you underpay (TAA 1994 s 120KE).
UOMI is interest charged on underpaid provisional or terminal tax. The debit rate (what you pay IRD) is currently 10.88% per year (TAA 1994 s 120E). If you overpay provisional tax, IRD also pays you a credit rate (lower). UOMI is calculated daily on the unpaid amount from each instalment due date.
Yes. The estimation method lets you pay based on your best estimate of the current year's residual income tax. This is useful if your income has dropped significantly. However, if you underestimate and underpay relative to the standard uplift amount, UOMI applies from each instalment date if you are over the $60,000 safe-harbour cap. Get your accountant's advice before switching methods.
The instalment offsets are the same (5, 9, and 13 months from the prior balance month) but the actual calendar dates shift. For example, a 30 June balance-date filer has P1 due 28 November, P2 due 28 March, and P3 due 28 July. If any instalment falls in December it moves to 15 January; if it falls on 28 April it moves to 7 May.
Yes. PayWren's Solo plan includes a provisional tax planner that tracks your instalment schedule, applies the standard uplift method to your PayWren data, and updates your reserve as you invoice and expense throughout the year. The tax planner is on your dashboard once you upgrade.
Your provisional tax schedule, safe-harbour status, and a reserve figure that updates as you invoice, all on your dashboard. Solo plan, $12/month.
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