RWT and PIR Explained

🏦 Tax on Your Savings and Investments

When your savings earn interest, or your investment fund earns returns, the tax is usually taken before the money reaches you. Two terms govern this: resident withholding tax (RWT) on interest, and the prescribed investor rate (PIR) on PIE funds. Getting these right means you pay the correct tax, avoid a surprise bill, and do not overpay.

                Key Point: RWT is the tax deducted from interest your bank pays you, at a rate based on your income. PIR is the rate used to tax income from PIE funds, including many KiwiSaver and managed funds. Both should match your income so you pay the right amount. Give your bank or fund your IRD number and the correct rate. Use a rate that is too low and you may face a bill; the PIR in particular is capped, so getting it right matters.
            

Two Systems, One Goal

Term	Applies To	What It Does
RWT	Interest from banks and similar	Tax deducted from your interest before you receive it
PIR	Income from PIE funds	Sets the tax rate on your share of the fund's income

Why the Tax Is Taken at Source

Deducting tax before you receive the money means most people do not have to calculate and pay it separately. The catch is that the rate used must match your situation, or you can end up paying too much or too little.

💵 Resident Withholding Tax on Interest

How RWT Works

When your bank pays interest on a savings account or term deposit, it deducts RWT and sends it to Inland Revenue. The rate you choose should line up with your income tax rate, so the deduction roughly matches what you actually owe on that interest.

Your account earns, say, $500 of interest

The bank deducts RWT at your chosen rate

You receive the interest net of that tax

The RWT is credited against your tax for the year

Choosing Your RWT Rate

Match it to your income: Pick the RWT rate that aligns with your marginal tax rate.
Give your IRD number: Without it, interest can be taxed at a high no-declaration rate.
Update it if your income changes: A pay rise or drop can change the right rate.

                Provide your IRD number: If your bank does not have your IRD number, your interest may be taxed at the highest no-notification rate, which is more than most people should pay. A quick update fixes it.
            

What If the Rate Is Wrong?

If your RWT rate is too low, you may have more tax to pay when your income is squared up. If it is too high, you may get some back. Either way, choosing a rate that matches your income keeps things tidy.

📊 The Prescribed Investor Rate for PIE Funds

What a PIE Is

A portfolio investment entity, or PIE, is a common structure for KiwiSaver funds, managed funds, and some term deposits. Income from a PIE is taxed at your PIR rather than your full income tax rate, and the PIR is capped at a maximum.

How Your PIR Is Worked Out

Your PIR is based on your income over the last two years, using the lower of the two years in the standard test. There are a small number of set PIR rates, and you tell your fund which one applies to you.

Look at your income over the last two years

Apply the PIR test to find your rate

Tell your KiwiSaver or managed fund that rate

The fund taxes your share of its income at that rate

Why Getting the PIR Right Matters

Too low: You underpay, and Inland Revenue can issue a bill to square it up.
Too high: You may overpay tax on your investment income.
The cap helps higher earners: Because the PIR is capped below the top income tax rate, PIE income can be taxed at a lower rate than other income for high earners.

                Check your PIR yearly: Inland Revenue checks PIRs and will notify you if yours looks wrong, but it pays to review it yourself, especially after a big change in income, so you neither overpay nor build up a bill.
            

💡 Getting It Right and Common Mistakes

Common Mistakes

Mistake 1: Not Giving Your IRD Number

Leaving your IRD number off a savings account can mean interest is taxed at the highest no-declaration rate. Always provide it.

Mistake 2: Leaving the Default PIR

If you never set a PIR, a fund may use the highest rate. Many people overpay simply because they never told their fund the right rate.

Mistake 3: Setting a Rate Too Low to Pay Less Now

Choosing a low rate does not avoid the tax; it just defers it. You can end up with a bill when your income is squared up.

Mistake 4: Never Reviewing After an Income Change

A new job, a pay rise, or stopping work can all change your correct RWT rate and PIR. Review them when your income changes.

A Simple Check

1. Make sure every account and fund has your IRD number

2. Set your RWT rate to match your income

3. Work out your PIR and tell each PIE fund

4. Review both after any significant income change

5. Watch for any Inland Revenue notice about your rates

For tax basics that sit alongside this, see our Progressive Tax System guide, and the NZ Tax Rates reference for current figures.

Final word: RWT and PIR are how the tax on your savings and investments is collected before you ever see the money. The whole game is using the right rate: provide your IRD number, match your RWT rate to your income, and set the correct PIR with each fund. Review after income changes. This is general information, not personalised advice, and the rates and thresholds can change, so confirm the current figures.

🎯 Test Your Knowledge

Quiz on RWT and PIR (20 Questions)

1. RWT is tax on:

Interest your bank pays you

Your wages

Your groceries

Your KiwiSaver employer contribution

2. PIR applies to income from:

PIE funds, including many KiwiSaver and managed funds

Your salary

Your rent

Your power bill

3. RWT is deducted:

Before the interest reaches you

Only at the end of your life

Never

By you, manually each week

4. Your RWT rate should:

Match your income tax rate

Always be the lowest option

Be chosen at random

Be set by your employer

5. If your bank lacks your IRD number, interest may be taxed at:

The highest no-declaration rate

Zero

The lowest rate

A negative rate

6. A PIE is a:

Portfolio investment entity

Personal income estimate

Public interest exemption

Property insurance entity

7. The PIR is:

Capped at a maximum below the top income tax rate

Always 39%

The same as GST

Unlimited

8. Your PIR is based on your income over:

The last two years

The next ten years

This week

Your whole life

9. If your PIR is too low, you may:

Underpay and get a bill to square it up

Always get a refund

Pay no tax ever

Lose your investment

10. If your PIR is too high, you may:

Overpay tax on your investment income

Earn more interest

Get a lower fee

Avoid all tax

11. You set your PIR by:

Telling your KiwiSaver or managed fund the right rate

Telling your employer

Doing nothing

Calling the Reserve Bank

12. Why is tax taken at source on interest and PIE income?

So most people do not have to calculate and pay it separately

To make it harder

Because it is optional

To avoid IRD involvement

13. For high earners, PIE income can be taxed:

At a lower rate than other income, due to the PIR cap

At a higher rate than wages

At 0%

Twice

14. Leaving the default PIR can mean:

Being taxed at the highest rate and overpaying

Paying no tax

A guaranteed refund

Higher returns

15. Choosing a rate too low to pay less now:

Just defers the tax and can create a bill

Permanently avoids the tax

Is recommended

Increases your interest

16. You should review your RWT rate and PIR:

After any significant income change

Never

Only once in your life

Every day

17. Inland Revenue:

Checks PIRs and notifies you if yours looks wrong

Never looks at PIRs

Sets your fund fees

Pays your interest

18. RWT deducted during the year is:

Credited against your tax for the year

Lost

A separate penalty

Refunded to the bank

19. The whole game with RWT and PIR is:

Using the right rate for your situation

Avoiding all banks

Never investing

Paying cash only

20. The first step in getting it right is:

Making sure every account and fund has your IRD number

Closing all your accounts

Ignoring your statements

Setting the lowest possible rate

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