Should You Pay Off Your Mortgage Faster or Invest? A NZ Guide

It is one of the most common financial dilemmas New Zealand homeowners face, and if you search online, you will find passionate advocates on both sides. Some will tell you that paying off your mortgage is foolish when you could earn higher returns in the share market. Others insist that becoming debt-free should be your absolute priority, and that chasing investment returns while carrying mortgage debt is reckless.

The truth, as with most personal finance questions, depends entirely on your individual circumstances. But understanding the key factors can help you make a decision that is right for your situation, rather than following generic advice that might not apply to you.

The Core Question: Guaranteed Return vs Potential Higher Return

At its heart, this decision comes down to comparing two fundamentally different types of returns. When you pay extra off your mortgage, you earn a guaranteed, risk-free return equal to your mortgage interest rate. When you invest, you have the potential to earn higher returns, but those returns are neither guaranteed nor predictable.

Let us say your mortgage interest rate is 6.5%. Every dollar you pay off your mortgage effectively earns you 6.5% , guaranteed, tax-free, and with zero risk of losing that return. There is no investment in the world that can offer you a guaranteed 6.5% return with zero risk. The closest comparison would be term deposits, which at the time of writing offer significantly less.

On the other hand, investing in a diversified share portfolio has historically delivered higher average returns over long periods. The New Zealand share market has returned an average of around 9-10% per year over the past few decades, and global shares have performed similarly. If you could reliably earn 9% on investments while your mortgage costs 6.5%, the maths seems to favour investing.

But that 9% average is exactly that , an average. Some years the market returns 25%. Other years it drops 30%. You cannot control when the good years and bad years occur, and if you need the money during a downturn, you might be forced to sell at a loss.

Investment Returns: What History Actually Shows

When investment advocates talk about share market returns, they typically quote long-term historical averages. And those averages are real , over 20 or 30-year periods, diversified share portfolios have generally outperformed mortgage interest rates. But averages can be misleading.

The sequence of returns matters enormously. If you invest for ten years and the first five are strong followed by a crash, you end up in a very different position than if you experienced the crash first and then the recovery. The path matters, not just the destination.

It is also worth remembering that past performance is genuinely not indicative of future results. We have had several decades of generally favourable conditions for share market investors, including declining interest rates, globalisation, and technological innovation. There is no guarantee the next few decades will be as kind.

Tax Considerations in New Zealand

Tax treatment significantly affects this calculation, and New Zealand has some specific rules that matter. Understanding these can materially change which option makes more sense for you.

Mortgage Interest: Not Deductible for Owner-Occupied Homes

Unlike some countries, New Zealand does not allow you to deduct mortgage interest on your owner-occupied home against your income. This means you are paying that mortgage with after-tax dollars. If you are on the 33% tax rate and earning $100 to make a mortgage payment, you actually need to earn about $149 before tax to make that $100 payment.

This makes paying off your mortgage relatively more attractive compared to countries where mortgage interest is tax-deductible.

PIE Funds: Capped Tax Rates

Portfolio Investment Entities (PIE funds) in New Zealand have their tax rate capped at 28%, regardless of your marginal tax rate. This is a significant advantage for higher earners who would otherwise pay 33% or 39% on investment income.

If you are on the 39% tax rate, investing through a PIE fund means you pay 28% on your investment returns rather than 39%. This effectively boosts your after-tax returns and makes investing more attractive relative to mortgage payoff.

FIF Tax on International Investments

If you hold more than $50,000 in foreign shares outside of a PIE fund, the Foreign Investment Fund (FIF) rules apply. Under the Fair Dividend Rate method (the most common approach), you are taxed on 5% of your opening balance each year, regardless of actual returns.

This can work for or against you. In strong years, you might pay less tax than on actual returns. In bad years, you still owe tax even if your investments lost money. For most investors, using PIE funds to access international markets is simpler and often more tax-efficient.

Risk Tolerance: An Honest Assessment

Your personal risk tolerance should heavily influence this decision, and it is worth being brutally honest with yourself. Many people overestimate their tolerance for investment volatility when markets are rising and discover their true risk tolerance only when markets crash.

Ask yourself: how did you feel during the March 2020 COVID crash, when markets fell 30% in a matter of weeks? If you already had investments, did you sell in panic, hold steady, or buy more? Your actual behaviour during stressful periods is a much better indicator of your risk tolerance than your theoretical beliefs.

Age and Time Horizon

Your age and how long until you need the money matters enormously. Investment returns are more predictable over longer time horizons. The probability of shares outperforming a mortgage interest rate over 25 years is much higher than over 5 years.

If you are 35 with a 30-year mortgage horizon, you have time to ride out market volatility. Historical data strongly favours investing over such long periods. But if you are 55 and hoping to retire at 65, the picture changes. A major market downturn in your early 60s could significantly delay your retirement if you were counting on investment gains to fund it.

Consider when you actually need the money. Mortgage payoff provides certainty , you know exactly when you will be debt-free. Investment returns provide probability , over long periods, you will likely come out ahead, but there are no guarantees about timing.

The Emergency Fund Question

Before aggressively pursuing either mortgage payoff or investing, you need an adequate emergency fund. This is non-negotiable and should be your first financial priority after meeting minimum debt payments.

An emergency fund of three to six months of expenses provides a buffer against unexpected events , job loss, major repairs, health issues. Without this buffer, you might be forced to take on expensive debt or sell investments at an inopportune time to cover emergencies.

The Psychological Value of Being Mortgage-Free

Numbers and spreadsheets cannot capture everything. There is genuine psychological value in owning your home outright with no debt hanging over you. This is not irrational , it is a legitimate consideration that pure financial analysis often ignores.

Being mortgage-free provides security that investments cannot match. No matter what happens in your career or the economy, you have a roof over your head that no one can take away. You can take career risks, pursue passion projects, or weather job losses with much less stress.

The reduction in mandatory monthly outgoings is also significant. Without a mortgage payment, your baseline expenses drop dramatically. This provides flexibility that is hard to quantify but very real in practice.

KiwiSaver: The Exception That Proves the Rule

Before deciding between mortgage payoff and other investments, make sure you are maximising KiwiSaver benefits. The employer contribution (if you are employed) and government contribution are essentially free money that dramatically boosts your effective returns.

Contributing at least 3% of your salary to get the full employer match is almost always worthwhile, even if you have mortgage debt. The employer contribution is an immediate 100% return on your contribution (assuming your employer matches at 3%). No other investment can offer that.

Contributing $1,042.86 per year (or $87 per fortnight) also secures the maximum $521.43 government contribution. Again, this is hard to beat with any other strategy.

A Balanced Approach: Doing Both

For many homeowners, the best answer is not to choose one or the other, but to do both in appropriate proportions. This approach captures some benefits of each strategy while managing the downsides.

A balanced approach might look like this: contribute to KiwiSaver at least up to the level that maximises employer and government contributions. Maintain an adequate emergency fund. Then split any additional surplus between extra mortgage payments and investments outside KiwiSaver.

The specific split depends on your circumstances. Someone with high risk tolerance, a long time horizon, and a lower mortgage rate might favour a 30/70 split toward investing. Someone more conservative, closer to retirement, or with a higher mortgage rate might favour 70/30 toward mortgage payoff.

When to Prioritise Mortgage Payoff

Certain situations clearly favour prioritising mortgage payoff over investing. If several of these apply to you, lean toward paying down your mortgage faster.

• High mortgage interest rate: If your rate is above 7%, the guaranteed return from paying it off becomes increasingly attractive compared to uncertain investment returns.
• Low risk tolerance: If investment volatility genuinely bothers you and affects your sleep or wellbeing, the certainty of mortgage payoff is valuable.
• Approaching retirement: If you are within 10-15 years of retirement, having your mortgage paid off provides security and reduces your required retirement income.
• Job insecurity: If your employment situation is uncertain, reducing fixed monthly obligations provides a valuable buffer.
• Already have adequate investments: If you have significant KiwiSaver balances and other investments, diversifying into mortgage reduction makes sense.
• The peace of mind matters to you: If being debt-free is a genuine priority that will improve your quality of life, that has real value.

When to Prioritise Investing

Conversely, some situations favour prioritising investments over mortgage payoff.

• Low mortgage interest rate: If your rate is below 5%, the opportunity cost of not investing is higher.
• Long time horizon: If you are young with 20+ years until retirement, time is on your side for riding out investment volatility.
• High income and tax bracket: The PIE tax cap at 28% makes investing more attractive for those on the 33% or 39% tax rate.
• Good risk tolerance: If you can genuinely handle investment volatility without emotional decisions, you are better positioned to capture long-term returns.
• Employer share schemes: If your employer offers discounted share purchases or matching contributions, these can offer excellent returns.
• Mortgage already manageable: If your mortgage payments are comfortable and not straining your budget, the urgency to pay it off faster is lower.

Common Mistakes to Avoid

Whichever approach you choose, be aware of these common mistakes that can undermine your strategy.

Running Your Own Numbers

While general principles are helpful, your specific situation requires specific calculations. Consider working through scenarios with your actual numbers: your mortgage rate, your expected investment returns (be conservative), your tax rate, and your time horizon.

Online calculators can help compare the outcomes of different strategies over various time periods. But remember that calculators assume constant returns, which never happens in reality. Run scenarios with both optimistic and pessimistic assumptions to understand the range of outcomes.

If the decision is close or your situation is complex, consider consulting a qualified financial adviser. A few hundred dollars for professional advice could be well spent on a decision that will affect tens or hundreds of thousands of dollars over your lifetime.

The Bottom Line

There is no universally correct answer to whether you should pay off your mortgage faster or invest. The right choice depends on your mortgage rate, risk tolerance, time horizon, tax situation, and personal values around debt and security.

For most New Zealand homeowners, a balanced approach makes sense: maximise KiwiSaver benefits first, maintain an emergency fund, then split additional surplus between mortgage and investments in a ratio that reflects your individual circumstances and preferences.

Do not let anyone tell you that either choice is definitively right or wrong. Both paying off your mortgage faster and investing are financially responsible behaviours. The best strategy is one you will actually stick with, that lets you sleep at night, and that moves you toward your long-term goals.

Whatever you decide, the fact that you are thinking about this question at all puts you ahead of most people. Making a conscious choice , even if it turns out to be slightly suboptimal in hindsight , is far better than drifting along without a strategy.