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Savings Calculator NZ (after RWT)
Free savings calculator for New Zealand: how your savings grow with a starting amount, monthly deposits and the interest rate, after resident withholding tax (10.5% to 39%).
Your savings
You'll have in 5 years
$31,479
| You deposited | $29,000 |
| Interest after tax | $2,479 |
Banks take resident withholding tax (RWT) from interest at the rate you choose, matched to your income. Without your IRD number it's 45%.
Interest added monthly at the same rate throughout; rates change. Not legal, tax or financial advice. 🔒 Everything stays on your device.
📚 Official sources: IRD: resident withholding tax
We build every tool from the official rules and re-check them when they change. Always confirm with the official source before you rely on a result.
🛠️ Spotted a mistake or an out-of-date rule? Tell us
Questions people ask
What RWT rate should I choose?+
The rate that matches your income: 10.5% up to $15,600, 17.5% to $53,500, 30% to $78,100, 33% to $180,000 and 39% above.
What if I don't give my IRD number?+
Your bank takes the non-declaration rate of 45%.