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?
The term deposit calculator computes the maturity value, gross interest, RWT deduction, and true after-tax return on NZ term deposits, with monthly, quarterly, annual, or at-maturity compounding.
How this calculator works
A term deposit locks your money at a fixed rate for a fixed term. The calculator applies the compound interest formula — principal × (1 + rate ÷ periods)^(periods × years) — using your chosen compounding frequency, then deducts resident withholding tax (RWT) from the interest at your elected rate: 10.5%, 17.5%, 30%, 33%, or 39% to match your income bracket, or a punitive 45% if the bank has no IRD number on file. The output that matters is the after-tax effective rate, because a headline 5.20% shrinks to about 3.6% for a 30% taxpayer — worth checking against inflation before locking in. Two practical notes: interest compounding within the term only applies if you leave interest to reinvest (paid-out interest earns nothing further), and breaking a term deposit early usually forfeits most or all interest, so laddering several maturities preserves flexibility.
NZ term deposit rates and tax (mid-2026)
| 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 on interest | 10.5% / 17.5% / 30% / 33% / 39% |
| No IRD number on file | 45% default deduction |
Indicative bank ranges; special rates move weekly with wholesale markets.
Worked Examples
$10,000 at 5.20% for 12 months, monthly compounding, 30% RWT
Maturity $10,533 gross; net interest $373 — after-tax effective rate ≈ 3.73%.
- Final: $10,000 × (1 + 0.052 ÷ 12)^12 = $10,532.60
- Gross interest: $532.60
- RWT: $532.60 × 30% = $159.80
- Net interest: $372.80 → effective after-tax return ≈ 3.73%
$25,000 at 5.35% for 6 months, interest at maturity, 17.5% RWT
Gross interest $668.75; RWT $117.03; net $551.72 at maturity.
- Simple interest for 6 months: $25,000 × 5.35% × 0.5 = $668.75
- RWT: $668.75 × 17.5% = $117.03
- Net interest: $551.72
- Returned at maturity: $25,551.72
Built and maintained by Konstantin Iakovlev. Data sourced from the IRD and official New Zealand government sources.
Last reviewed: