Should You Make Extra Mortgage Payments?

The pros and cons of making extra mortgage repayments, and how to decide what works for your situation.

Buying a home is a milestone. Paying it off is a marathon. With a standard 30-year loan term, most New Zealand homeowners will spend decades making monthly repayments, and it is natural to wonder whether putting extra money towards the mortgage would be a good idea.

The short answer: it depends. Extra repayments save tens of thousands of dollars in interest and shave years off your loan. But every dollar directed at the mortgage is a dollar unavailable for other purposes, and those purposes might serve you better in the long run. This is the concept of opportunity cost, and it sits at the heart of the decision.

This article is most useful if you own a home with a mortgage, have some surplus income or savings each month, and are weighing up whether to accelerate repayments or do something else with the money.

It is less relevant if you are still saving for a deposit, are on an interest-only loan for investment purposes, or are struggling to meet existing repayments.

The Case for Extra Mortgage Repayments

How Extra Repayments Reduce Interest Costs

Interest is the biggest hidden cost of homeownership. Over the life of a 30-year mortgage, interest charges can rival or exceed the original amount borrowed. By making extra payments, you reduce the principal balance faster, which means less interest accrues over time.

The effect compounds. Even a modest increase in regular payments can cut the loan term by several years and deliver significant savings. The exact figures depend on your interest rate and remaining term. The government-backed financial literacy site Sorted offers a mortgage calculator where you can model the impact for your specific situation.

A further advantage: by reducing your principal sooner, you become less exposed to future interest rate increases. Higher rates will apply to a smaller balance, or to no balance at all.

Why Extra Repayments Build Equity Faster

Equity is the difference between your home’s market value and the amount still owed. Extra repayments accelerate equity growth, which can open doors: the ability to refinance on better terms, access equity for other opportunities, or simply carry less risk if property values soften.

The Financial Freedom of Being Mortgage-Free

Once the mortgage is gone, a significant chunk of your monthly expenses disappears. The freed-up cash flow can be redirected towards investing, retirement planning, travel, a career change, or simply enjoying life with fewer financial commitments.

For many homeowners, the peace of mind is the strongest argument. Owning your home outright, free from any bank or lender, brings a sense of security. Whatever happens in the economy, your housing costs will be minimal (though you will still need to cover insurance, council rates, water charges, and maintenance).

Before You Accelerate: Five Things to Do First

Extra mortgage repayments are rarely the first best use of surplus income. Before directing additional funds towards the home loan, consider whether any of the following apply.

1. Clear Higher-Interest Debt First

Credit cards, vehicle finance, store cards, and buy now pay later schemes all carry interest rates far above typical mortgage rates, sometimes five to ten times higher. It makes little sense to chip away at a 5% mortgage while carrying a 22% credit card balance. Eliminate expensive consumer debt first, then reassess.

2. Build an Emergency Fund

Money inside your mortgage is not easily retrieved. Unlike a savings account, getting it back typically requires a formal application to your bank, approval, and potentially additional fees.

An emergency fund of three to six months’ worth of living expenses provides a safety net for the unexpected: job loss, car repairs, urgent travel, a major appliance failing. Without one, directing all surplus income into the mortgage could leave you exposed.

3. Capture Your Full KiwiSaver Employer Match

If your employer matches your KiwiSaver contributions (up to 3.5% of gross salary for most employees from 1 April 2026, rising to 4% on 1 April 2028), ensure you are contributing enough to capture the full match. This is effectively a 100% return on the matched portion, and few uses of money can beat it on a risk-adjusted basis.

Note: employer contributions vary. Some employment agreements use total remuneration packages or offer different matching arrangements, so check your specific terms.

4. Understand the Tax Picture

New Zealand does not offer a tax deduction on mortgage interest for owner-occupied homes, unlike some countries. This means the cost of your mortgage is the stated interest rate, with no tax benefit to offset it.

Conversely, some investment returns in New Zealand are taxed favourably. Returns within a PIE (Portfolio Investment Entity) fund, as defined under Inland Revenue’s managed fund tax rules, are taxed at your prescribed investor rate, capped at 28% and often lower. When comparing the cost of keeping a mortgage against potential investment returns, factor in after-tax returns on the investment side.

5. Check Your Fixed Rate Terms

In practice, most New Zealand mortgages are on fixed interest rates. Banks generally allow you to increase regular repayments by a set percentage each year (commonly around 5% of the outstanding balance, though terms vary by lender). Larger lump sum payments during a fixed term can trigger break fees.

If you have a lump sum to deploy, check with your lender about the allowances and any potential costs. In some cases, it may be wiser to hold the funds in an offset account or revolving credit facility (more on these below) until your fixed term expires, then make the payment without penalty.

The right answer depends on your full financial picture. This is where personalised advice usually matters more than rules of thumb.

The Case for Putting Your Money to Work Elsewhere

Opportunity Cost: the Real Question

Every extra dollar paid towards the mortgage earns a guaranteed “return” equal to the interest rate on the loan. If your mortgage rate is 5%, each extra dollar saves you 5% in interest.

The question is whether you could do better elsewhere. Over the long term, diversified investment portfolios have historically delivered returns above typical mortgage interest rates. No one can guarantee future performance, and markets are volatile in the short term, but for those with a time horizon of a decade or more, the historical evidence favours investing surplus cash over accelerating mortgage repayments.

The gap between your mortgage rate and the expected investment return is sometimes called the spread. The wider it is, the stronger the case for investing. Inflation can also play a role: over time, a fixed mortgage balance effectively shrinks in real terms if wages and prices rise, which can further strengthen the case for directing surplus cash towards appreciating assets. For a deeper exploration, see our article on borrowing to invest.

Why Liquidity Matters More Than Interest Saved

Liquidity is the ability to access your money when you need it. Money paid into a mortgage is locked away. Retrieving it means going back to the bank to apply for additional lending, with no guarantee of approval.

By contrast, most managed funds and other non-KiwiSaver investments can be accessed at any time, usually without penalty or withdrawal fee. We regularly see clients benefit from this flexibility: a year off work, an opportunity to buy into a business, school fees, a renovation. Liquid investments give you options. A paid-down mortgage does not.

Diversification Beyond Property

For many New Zealanders, a home and a KiwiSaver balance represent the vast majority of their net worth. Extra mortgage repayments concentrate wealth further into a single, illiquid asset in a single location.

Directing surplus income towards a well-diversified portfolio spreads risk across geographies, asset classes, and currencies. Over time, this reduces the volatility of your overall wealth, which becomes particularly relevant as you approach retirement.

Some homeowners go further, using a technique called debt recycling to convert non-deductible mortgage debt into an investment portfolio alongside their home. In practical terms, this means borrowing against the equity you have already built to invest in income-producing assets, while the original mortgage is gradually repaid.

Practical Tools Available in New Zealand

You do not have to choose one path exclusively. Several mortgage structures available from New Zealand banks allow you to reduce interest while retaining flexibility.

Revolving Credit

A revolving credit facility is a flexible mortgage account, functioning like a large overdraft secured against your home. Your salary goes in, your expenses come out, and interest is calculated daily on the outstanding balance. Every dollar sitting in the account reduces the interest you pay.

The key advantage over standard extra repayments: funds in a revolving credit can be withdrawn at any time without reapplying for lending. In practice, most lenders suggest keeping the revolving portion relatively small (perhaps $20,000 to $50,000) to limit exposure to floating interest rates, which are typically higher than fixed rates.

Revolving credit suits disciplined budgeters. If the constant availability of funds is too tempting, it may not be the right fit.

Offset Accounts

An offset account is a savings account linked to your mortgage, where the balance reduces the interest charged on the loan. A $500,000 mortgage with $40,000 in linked savings means you only pay interest on $460,000.

Your savings remain accessible, though you will not earn interest on the linked balances. The trade-off is usually worthwhile: the interest saved on the mortgage is often greater than the interest you would have earned in a standard savings account. Some parents use offset arrangements to help adult children with their mortgage costs without gifting capital outright.

Refinancing and Restructuring

Rather than directing extra cash towards the mortgage principal, it may be worth reviewing the mortgage itself. Refinancing (switching lenders for a better deal) or restructuring (rearranging fixed and floating portions, terms, and repayment levels) can reduce interest costs without tying up additional capital.

Banks compete strongly for mortgage business. Many homeowners find they can reduce their repayments while maintaining the same payoff timeline, or keep repayments the same and shave years off the loan, simply by restructuring at the right time. Banks often reserve their best deals for new customers, so it can make sense to switch lenders every few years after weighing the costs and benefits, including any cash-back offers available.

Talk with our lending team to see if this might make sense for your situation.

How to Decide: a Simple Framework

There is no universal right answer. The best approach depends on your circumstances. Three factors matter most.

Your appetite for risk and what lets you sleep at night. Extra mortgage repayments offer a guaranteed return equal to your interest rate. Investing involves uncertainty and short-term volatility. Some people find it motivating to watch a mortgage balance shrink; others prefer to build wealth through a diversified portfolio. The approach you will actually stick with matters more than the theoretically optimal one.

Your time horizon. The longer you have before you need the money, the more time investments have to ride out volatility and benefit from compounding. A 35-year-old with decades of earning ahead has a different calculus from a 58-year-old approaching retirement.

Your starting position. If you have no emergency fund, carry consumer debt, or have not captured your full KiwiSaver employer match, address those priorities first. Neither extra mortgage repayments nor investing should come at the expense of financial fundamentals.

And remember: you do not have to pick one or the other. Many homeowners split their surplus, directing some towards accelerating the mortgage and some into a diversified investment. This captures some of the guaranteed interest savings while preserving liquidity and diversification.

The Bottom Line: Should You Make Extra Mortgage Payments?

Extra mortgage repayments are one of the simplest and most predictable financial moves available. They reduce debt, save interest, and bring you closer to owning your home outright. For many homeowners, this alone is reason enough.

But simple does not always mean optimal. Depending on your interest rate, time horizon, and financial goals, surplus cash may work harder elsewhere. A considered blend of debt reduction, investing, and smart mortgage structuring often delivers the best outcome over time.

If you are weighing up your options, book a complimentary initial consultation with our team. We can help you work out which combination of repayment, investment, and mortgage structuring suits your situation.