According to an update from New Zealand Inland Revenue, the use of money interest (UOMI) rates on tax underpayments and overpayments are as follows from 16 January 2026:
- Underpayments - 8.97%, down from 9.89%,
- Overpayments - 2.25%, down from 3.27%,
The prior rates applied from 8 May 2025.
Inland Revenue has also published a new guide on Penalties and interest, dated February 2026.