RWT and PIR: Tax on Interest and Investments

📊 Choosing Your RWT Rate

Match the Rate to Your Tax Bracket

RWT rates line up with the income tax brackets, so you choose the one that matches the top tax rate you pay on your overall income. The idea is that the tax taken from your interest matches what you would owe on that income anyway.

RWT Rates for Individuals (2026/27):

You nominate your RWT rate with each bank or payer, usually when you open an account. If your income changes brackets, update the rate so it keeps matching.

The No-Notification Rate

If you do not give a payer your IRD number, they must deduct RWT at the no-notification rate of 45%, far above any normal bracket. This is not a penalty you can never recover, but it means heavy over-deduction until you provide your details and the year-end assessment corrects it. Supplying your IRD number avoids the whole problem.

Getting the RWT Rate Wrong

• Too low: If you pick a rate below your real bracket, not enough tax is taken and you will owe the difference at year end.
• Too high: If you pick a rate above your bracket, too much is taken; you have over-paid and will get it back at the square-up.

🏦 PIR and PIE Funds

What a PIE Is

A Portfolio Investment Entity, or PIE, is a special tax structure used by most KiwiSaver schemes, managed funds and many cash funds. Instead of RWT, a PIE taxes your share of its income at your Prescribed Investor Rate, your PIR. The standout feature is that the top PIR is capped at 28%.

The Three PIRs

There are three prescribed investor rates, and your PIR is based on your income over the last two years, using the lower-rate test where it applies.

You tell your KiwiSaver scheme or fund your PIR, and they apply it. The exact income tests for the lower rates have specific thresholds, so it is worth checking yours rather than guessing.

Getting Your PIR Wrong

For years, an under-stated PIR could leave you with a bill while an over-stated one was simply lost. Now PIE income is included in your end-of-year assessment, so the system squares it up: too low and you pay the shortfall, too high and the over-payment is refunded. Even so, using the correct PIR keeps your cashflow right and avoids surprises.

Use our KiwiSaver Calculator to project your balance, and check your PIR with your provider so the right rate is applied.

✅ Common Mistakes and What to Do

Mistake 1: Not Giving Your IRD Number

The trap: Opening a savings account or term deposit without supplying your IRD number.

Why it costs: Interest is taxed at the 45% no-notification rate, far more than your real bracket, tying up your money until it is corrected. Always provide your IRD number.

Mistake 2: An Out-of-Date RWT Rate

The trap: Setting an RWT rate years ago and never updating it after a pay rise or pay cut.

Why it costs: A rate that no longer matches your bracket means over or under-deduction. Review your RWT rate whenever your income changes brackets.

Mistake 3: An Incorrect PIR

The trap: Guessing your PIR or never setting it, so the default applies.

Why it costs: Too low and you face a shortfall at year end; too high and your cashflow suffers until the refund. Check your PIR against your income over the last two years.

Mistake 4: Missing the PIE Advantage

The trap: A high earner holding investments directly and paying 33% or 39%, when a PIE would cap the rate at 28%.

Why it costs: Paying more tax than necessary on the same returns. For higher earners, the PIE structure can be more tax-efficient.

A Simple Action Plan

Where to Go Next

Use the Compound Interest Calculator for savings growth, the KiwiSaver Calculator for your fund, and the PAYE Calculator to find your tax bracket.

Final word: RWT taxes your interest and dividends at the rate you nominate, so match it to your bracket and always give your IRD number. PIE income is taxed at your PIR, capped at a useful 28%, so set the right rate and enjoy the cap if you are a higher earner. Keep both rates current and the year-end assessment will tidy up the rest. This is general information, not personalised tax advice, so confirm your rates with your provider or Inland Revenue.