Use-of-money interest is IRD's way of charging for tax paid late, and the rate is high enough to hurt. The good news is that with a bit of planning, most small businesses can avoid it entirely.
Quick answer
Use-of-money interest (UOMI) is interest IRD charges when you pay tax late or underpay it during the year. It is not a penalty, it is interest on money the tax system is owed, and the rate is meaningfully higher than a bank deposit rate. The main way to avoid it is the provisional-tax safe harbour: pay the standard amounts on time and you are generally protected from UOMI on your provisional tax.
The detail, in plain English
UOMI exists because tax is meant to be paid as income is earned, not all at the end. If you pay less than you should during the year, IRD charges interest on the shortfall until you catch up. A few things are worth knowing:
- It works both ways. If you overpay, IRD can pay you interest, though at a lower rate than it charges, so deliberately overpaying is not a good strategy.
- It is separate from penalties. Late-payment penalties can apply on top of UOMI, so missing a date can attract both.
- The safe harbour is your shield. If your residual income tax is under the safe-harbour limit and you pay the standard provisional amounts on time, you are generally protected from UOMI for that year.
- Tax pooling can reduce it. Using a tax pool to settle a shortfall can cut the effective interest cost compared with paying IRD's UOMI directly.
In other words, UOMI is largely a planning problem. Pay the right amounts at the right times and it rarely bites.
A simple example
A business has a much stronger year than expected, so its real tax is well above what the provisional instalments covered:
| Item | Amount |
|---|---|
| Provisional tax paid during the year | $9,000 |
| Actual residual income tax | $15,000 |
| Shortfall carried late | $6,000 |
UOMI is charged on that $6,000 shortfall from when it should have been paid until it is settled. If the business had qualified for the safe harbour by paying the standard amounts on time, it would generally have been protected. Where the safe harbour does not apply, tax pooling can soften the interest cost on the catch-up.
Common mistakes to avoid
- Under-estimating provisional tax to pay less now. It creates a shortfall that UOMI then charges on.
- Assuming UOMI is a penalty you can argue away. It is interest, and it accrues on the numbers.
- Missing the safe harbour by paying late. The protection generally needs the standard amounts paid on time.
- Ignoring tax pooling. For a genuine shortfall, a tax pool can reduce the effective interest.
Where this fits in your return
UOMI is closely tied to provisional tax and the safe harbour that protects you from it. Where a real shortfall exists, it connects to the broader tax-debt and disputes service for managing the balance.
How Fernway can help
We plan your provisional tax so you stay inside the safe harbour wherever possible, forecast a strong year early so a shortfall does not creep up, and use tax pooling when it will cut the interest on a genuine catch-up. The aim is simple: pay the right tax at the right time and pay little or no UOMI. Fixed fee, agreed before we start.
Book a free 20-minute review and we will check your exposure.
This is general information only, not personalised tax advice. Confirm your situation with us or check ird.govt.nz.
In plain English: use-of-money interest is what IRD charges for tax paid late, so pay the standard provisional amounts on time to stay in the safe harbour, and use tax pooling to soften any genuine shortfall.
This is general information, not personalised tax advice.See our full disclaimer.