Pay Off Mortgage vs Invest in New Zealand 2026 — Which Wins?
One of the most common financial questions New Zealanders ask: should I put extra money into my mortgage, or invest it? There’s no universal answer — but the maths gives you a clear framework.
If your mortgage rate is 6.5–7.0% and your after-tax investment return is 7–9%, the numbers roughly tie — but the mortgage wins risk-adjusted because the return is guaranteed. When rates were 2–3% (2020–2021) investing clearly won. At current NZ rates, a hybrid strategy (some of both) is usually sensible.
The Core Maths
Every dollar you put into your mortgage earns you a guaranteed, risk-free return equal to your mortgage interest rate. No tax is owed on this “return” — you’re simply avoiding interest.
Every dollar you invest earns a variable, taxable return that depends on markets.
The comparison:
| Factor | Paying off mortgage | Investing (index fund) |
|---|---|---|
| Return | Mortgage rate (guaranteed) | ~8–10% p.a. historic (not guaranteed) |
| Tax on return | None | PIR applies to fund earnings |
| Risk | Zero | Market volatility |
| Liquidity | Low (equity is locked unless you redraw) | High (can sell) |
| Psychological benefit | High for many people | Varies |
NZ Interest Rates in 2026
| Mortgage type | Approximate rate (May 2026) |
|---|---|
| Floating | ~7.0% p.a. |
| 6-month fixed | ~6.3% p.a. |
| 1-year fixed | ~6.0–6.2% p.a. |
| 2-year fixed | ~5.9–6.1% p.a. |
| 3-year fixed | ~5.8–6.0% p.a. |
Rates change constantly — check interest.co.nz for current rates.
After-Tax Investment Returns in NZ
NZ investment returns are taxed at your Prescribed Investor Rate (PIR), which ranges from 10.5% to 28% depending on your income.
| PIR rate | Who it applies to |
|---|---|
| 10.5% | Income up to $14,000/year |
| 17.5% | Income $14,001–$48,000/year |
| 28% | Income above $48,000/year |
Example: A diversified NZ/international index fund earning 9% p.a. gross, with a 28% PIR:
- After-tax return = 9% × (1 – 0.28) = 6.48% p.a.
At a floating mortgage rate of 7.0%, paying down the mortgage wins on raw numbers.
At a 1-year fixed rate of 6.1%, and investing at 6.48% after PIR — investing has a marginal edge, but not by much, and carries all the market risk.
Worked Examples
Scenario A — $50,000 lump sum, 7% floating mortgage, 28% PIR
Option 1: Pay off mortgage
- $50,000 reducing principal at 7% saves $3,500/year in interest (risk-free)
Option 2: Invest in index fund
- Assume 9% gross return, 28% PIR → 6.48% after-tax
- $50,000 × 6.48% = $3,240/year after tax (variable, may be higher or lower)
Result: Paying off the mortgage wins by ~$260/year on these assumptions — plus no volatility risk.
Scenario B — 2-year fixed mortgage at 5.9%, 17.5% PIR
- Mortgage savings: $50,000 × 5.9% = $2,950/year (guaranteed)
- Investment: $50,000 × 9% × (1 – 0.175) = $3,712/year (variable)
Result: Investing has the edge — by about $762/year. But markets can return –10% in a bad year. The investor needs a long enough horizon to smooth volatility.
The Tax Advantage of the Mortgage
Paying down your mortgage earns an effective pre-tax return equal to your mortgage rate — but the “return” is tax-free (you’re avoiding a cost, not earning income).
To beat the mortgage on an after-tax basis, your investment needs to return:
$$\text{Required gross return} = \frac{\text{Mortgage rate}}{1 - \text{PIR}}$$
Example: Mortgage at 6.5%, PIR 28%: $$\frac{6.5%}{1 - 0.28} = 9.03%$$
You’d need a gross return above 9% to beat the mortgage — historically achievable with equities, but not guaranteed.
Factors That Tip the Balance
Pay off mortgage faster if:
- You’re within 5–10 years of retirement and want to own outright
- You lose sleep over debt or market volatility
- Your mortgage rate is floating or very high
- You have a low PIR (small tax advantage to investing)
- You have limited emergency fund — focus on that first, then mortgage
Invest more if:
- Your mortgage rate is fixed at below 5.5%
- You have a long investment horizon (20+ years)
- Your PIR is 10.5% or 17.5% (lower tax drag on returns)
- You’re young and building long-term wealth
- Your KiwiSaver employer match hasn’t been maximised — always do this first
The Hybrid Strategy
Most financial planners recommend a hybrid approach:
- Always maximise KiwiSaver employer contributions first — this is a 3% immediate return, guaranteed, before any other decision
- Maintain an emergency fund (3–6 months’ expenses)
- Make minimum mortgage repayments
- Split extra cash: e.g., 50% into mortgage offset/revolving credit, 50% into index funds
A revolving credit facility or offset mortgage lets you keep liquid savings earning the mortgage rate while remaining accessible — the best of both worlds.
What About KiwiSaver?
If you’re in KiwiSaver, your employer contributes 3% of your salary (you must contribute at least 3% to get this). This is an immediate 100% return on your contribution — always prioritise this over extra mortgage payments.
Do not pause KiwiSaver to pay off a mortgage faster. You lose the employer contribution, which compounds significantly over time.
Next Steps
- Check your current mortgage rate and type (fixed vs floating)
- Find your PIR using the IRD calculator (ird.govt.nz)
- Run the maths with your actual numbers using the scenarios above
- Consider a revolving credit facility if you want mortgage flexibility
- Talk to a fee-only financial adviser if you have significant surplus and complex decisions
→ Related: Debt Management Hub | Investing in NZ