Savings & Term Deposit Calculator

See the interest on savings or a term deposit, and what you keep after resident withholding tax (RWT), or in a PIE fund.

Amount you put in

Interest rate

A year (p.a.), as advertised

Type of account

For how long

Added each month

Tax on the interest

Interest you keep

$285.20

After 1 year at 4% p.a. (4.07% a year with interest on interest)

Balance at the end: $10,285
Tax on the interest: $122.22

Money you put in$10,000
Interest you keep$285
Tax$122

What this means

After tax, your savings earn about 2.85% a year. With prices rising around 2.5% a year, that’s about 0.4% a year more than inflation.

Shopping around pays: a rate just 0.5% higher would earn you $36.38 more after tax over 1 year.

Your bank deducts resident withholding tax (RWT) at the rate for your income. PIE savings funds cap the tax at your PIR, at most 28%.

Next step

Breakdown

Period	Interest	Tax	Balance
1 year	$407.42	$122.22	$10,285

What a better rate is worth

3%$212.91 after tax
3.5%$248.97 after tax
4%$285.20 after tax
4.5%$321.58 after tax
5%$358.13 after tax

Assumptions in this estimate

The rate stays the same for the whole period. Savings account rates can change at any time; fixed-term rates are set when you open the account.
Savings accounts add interest monthly. A term deposit adds it at the end of the term, or each year on terms over a year.
Tax is worked out on each year’s interest and taken from the balance, as when tax is deducted at source.
Money added each month goes in at the end of the month.

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How the calculator works

Amount and rate: what you put in, and the rate a year (p.a.).
Type of account: a savings account adds interest monthly, and you can add money each month. A term deposit fixes the rate and pays interest at the end, or yearly on longer terms.
Tax: pick your RWT rate, or the PIE option.

Example

A $10,000 term deposit at 4% p.a. for a year:

	RWT at 30%	RWT at 39%	PIE at 28%
Interest	$400	$400	$400
Tax	$120	$156	$112
Interest you keep	$280	$244	$288

Getting a better rate

Check your RWT rate: if it’s too low you’ll owe tax at the end of the year, and if it’s too high you’ve paid more than you need to.
Compare PIE options if you’re on 30% or more.
Watch for roll-overs: term deposits often renew at a lower rate unless you choose something else.

For longer-term growth, try the compound interest calculator.

Last updated October 19, 2026

Frequently asked questions

How much interest will $10,000 earn?

At 4% p.a. paid monthly, about $407 a year. At the 30% RWT rate, $122 is taken off, so you keep about $285.

Which RWT rate should I use?

The one for your total income: 10.5% up to $15,600, 17.5% up to $53,500, 30% up to $78,100, 33% up to $180,000 and 39% above that. If your bank doesn’t have your IRD number, it takes off 45%.

What is a PIE term deposit?

A term deposit run as a portfolio investment entity. Tax is charged at your prescribed investor rate (PIR), at most 28%, so if your income puts you on 30% or more, a PIE leaves you with more at the same rate.

Should I choose a savings account or a term deposit?

An on-call savings account lets you take money out at any time, but the rate can change. A term deposit fixes the rate; breaking it early usually needs notice, often 31 days, and costs some interest.

Is my money protected?

The Depositor Compensation Scheme protects up to $100,000 per depositor at each licensed bank, building society or credit union.