Term Deposit Calculator
Calculate maturity value, gross interest, and after-tax effective rate on NZ term deposits. Supports monthly/quarterly/annual/at-maturity compounding.
About this calculator
This calculator implements RBNZ wholesale rate data + IRD RWT rules from RBNZ + IRD (RWT). Last consulted 18 May 2026. Verify the figures yourself by following the link.
Current NZ term deposit rates (mid-2026)
Indicative — varies by bank, term, amount- •3-month rate: ~4.40–4.80%
- •6-month rate: ~4.85–5.20%
- •12-month rate: ~5.10–5.50%
- •2-year rate: ~5.00–5.30%
- •RWT applies on interest: 10.5%-39% (your marginal)
- •No IRD number: 45% default
Source: RBNZ — Interest rates
Disclaimer
This calculator provides estimates for general information purposes only. Results should not be relied upon as professional financial, tax, or legal advice. Tax rates and thresholds are based on publicly available IRD data and may change. Always consult a qualified tax agent or financial adviser for advice specific to your circumstances.
How NZ term deposit returns are calculated
Compound interest formula adjusted for NZ RWT on interest earned.
- 1
Compound interest formula
Final = P × (1 + r ÷ n)^(n×t)
P = principal, r = annual rate, n = compounding periods/yr, t = years.
- 2
Gross interest earned
Gross_interest = Final − P
The taxable interest amount.
- 3
RWT deduction
RWT = Gross_interest × your_RWT_rate
Bank deducts RWT at source. 10.5%, 17.5%, 30%, 33%, 39%, or 45% if no IRD#.
- 4
After-tax effective rate
Effective_rate = ((P + Net_interest) ÷ P)^(1÷t) − 1
Annualised return after tax.
Worked example
Inputs: $10,000 at 5.20% p.a., 12 months, monthly compounding, 30% RWT
Result: Final $10,532. Gross interest $532. RWT $160. Net $372. Effective 3.72% after tax.
Frequently Asked Questions
How is RWT taxed on a NZ term deposit?
Is compounding allowed on NZ term deposits?
What are the break fees on a NZ term deposit?
Should I split my term deposit across multiple banks?
How this calculator works
This term deposit calculator uses the latest data from official New Zealand government sources to provide accurate results. All calculations are performed in your browser — your data never leaves your device.
All calculations are performed in your browser — your data never leaves your device. Results are for general guidance only and should not be considered professional financial advice.
Built and maintained by Konstantin Iakovlev. Data sourced from the IRD and official New Zealand government sources.
Last reviewed: