Fixed vs Floating: How to Structure Your Mortgage in 2026

There's a persistent myth that mortgage structure decisions come down to predicting where interest rates are headed. Homeowners agonise over whether to fix or float, desperately trying to read economic tea leaves and outsmart the market. Here's the uncomfortable truth: even professional economists with access to sophisticated models and decades of experience get interest rate predictions wrong with remarkable consistency. If they can't reliably forecast where rates are going, what hope do you have?

The good news is that structuring your mortgage well doesn't actually require a crystal ball. It requires understanding your own financial situation, your tolerance for uncertainty, and how to use the tools available to create a loan structure that works regardless of what the economy decides to do next.

Understanding What You're Actually Choosing Between

A fixed rate mortgage is exactly what it sounds like: you lock in an interest rate for a specified period , typically anywhere from six months to five years , and your repayments stay constant for that duration. When the term ends, you either fix again at whatever rates are available or roll onto a floating rate.

A floating rate can move up and down with market conditions. The Reserve Bank says that when the OCR changes, mortgage, loan and savings rates often change too, but each lender decides timing, pricing and terms. This means repayments can change with relatively little notice, for better or worse.

• Fixed rates: Certainty and easy budgeting , you know exactly what your mortgage will cost for the next one, two, or three years.
• Floating rates: Flexibility , depending on lender terms, you may be able to make extra repayments or repay chunks of your loan with fewer break-fee issues than a fixed loan, and your rate may move if floating rates fall.

The mistake most people make is treating this as an either/or decision when it's really a spectrum.

The Case for Splitting Your Mortgage

Here's where things get more interesting. There's no rule saying your entire mortgage must be on a single rate type or term. Splitting your loan across multiple portions is one option worth discussing with a lender or mortgage adviser, yet many homeowners do not realise it may be available.

A split mortgage might have one portion fixed for two years, another fixed for three years, and a smaller floating or revolving credit portion for flexibility. This approach offers several advantages that a single-structure loan simply cannot match.

• Spreads interest-rate risk: If rates drop significantly, portions that come off fixed terms sooner may be repriced earlier. If rates rise, portions locked in for longer may keep their existing rate until the fixed term ends. You are not putting every portion on one refix date.
• Creates a rolling review cycle: When one portion expires, you can reassess and refix based on current conditions while the rest of your loan continues undisturbed. This is far less stressful than having a $600,000 mortgage all expiring simultaneously.
• Flexibility for extra payments: Keeping a floating or revolving portion gives you somewhere to park extra money when you have it. Received a bonus? Inheritance? Tax refund? A floating portion absorbs these windfalls and immediately reduces your interest costs.

Revolving Credit: The Misunderstood Tool

Speaking of flexibility, let's address revolving credit facilities, which are simultaneously one of the most useful and most abused mortgage features available.

A revolving credit facility works like a giant overdraft secured against your property. You have a limit , say, $50,000 , and your salary gets paid directly into it, reducing the balance and therefore the interest charged. You draw on it for expenses throughout the month, and ideally, the balance trends downward over time.

For disciplined borrowers, revolving credit can be useful. Money sitting in the account can reduce interest charged, while funds may remain accessible within the agreed limit. Check minimum payment expectations, fees and lender terms before relying on that flexibility.

For less disciplined borrowers, revolving credit is a trap. That available balance sitting there, accessible via your everyday banking, can prove irresistible. The facility that was supposed to help you pay off your mortgage faster instead becomes a permanent debt hovering near its limit, funding lifestyle expenses that should have been budgeted differently.

Be honest with yourself about which category you fall into. If you have previously let credit-card or overdraft balances creep up because available credit felt like "your money," discuss whether a large revolving credit facility is suitable before using one. There is no shame in choosing a simpler structure.

How Much Should You Keep Floating?

There is no official right percentage to keep floating or revolving. Some borrowers keep a smaller flexible portion and fix the remainder across one or more terms, but the suitable split depends on lender terms, budget, expected cash flow and risk tolerance.

However, rules of thumb are just starting points. Your ideal split depends on factors specific to your situation:

• Variable income: If you're self-employed, work on commission, or receive irregular bonuses, a larger floating portion lets you make bigger payments during good months without being locked into commitments you can't sustain during lean periods.
• Expecting a cash injection: If you are expecting to sell another property, receive an inheritance, or have maturing investments, ask your lender or adviser whether floating capacity could absorb that money without unnecessary break-fee risk.
• Certainty matters most: If predictability matters more to you than optimisation, weighting heavily toward fixed rates lets you sleep at night knowing exactly what your repayments will be.
• Tight finances: If your financial situation is tight and you need every dollar accounted for, a fully fixed structure with set repayments might actually serve you better than flexibility you can't afford to use.

The Term Length Question

Assuming you're fixing at least part of your mortgage, the question becomes: for how long? Six months? One year? Five years? Something in between?

Shorter terms typically offer lower rates but require more frequent renewals and expose you to rate changes sooner. Longer terms provide extended certainty but usually at a premium, and you're locked out of falling rates if they drop.

A staggered approach can be considered , perhaps fixing portions across different terms so something comes up for renewal within a reasonable timeframe. This can reduce the "all your eggs in one basket" problem where your entire mortgage refixes on one date.

The longest terms (four and five years) suit borrowers who prioritise certainty above all else and are willing to pay for it. They're also worth considering when rates are historically low and you want to lock in that position for as long as possible , though identifying "historically low" in the moment is harder than it sounds.

Building a Structure That Survives Contact With Reality

A suitable mortgage structure is not the one that would perform perfectly if you could predict the future. It is one that you can afford across a range of possible futures while matching how you actually manage money.

Before your next mortgage review, spend some time thinking about your genuine priorities. Consider how much payment certainty matters to you, whether you are likely to make extra payments or if that is aspirational thinking, what your realistic timeline in this property is, and how you would cope if rates moved significantly in either direction. Armed with honest answers to those questions, you can have a far more productive conversation with your lender or mortgage adviser about structuring your loan. You'll be making decisions based on self-knowledge rather than rate speculation.

Your Mortgage Structure Should Evolve

What works for you today might not work in five years. A mortgage structure suited to a young couple with variable income and no children might be entirely wrong for that same couple once they have kids, stable careers, and different priorities.

Treat your mortgage reviews as opportunities to reassess not just the rates on offer but the fundamental structure of your loan. As your life changes, your mortgage should change with it. Homeowners who review their mortgage structure consistently may be better placed to spot risks, ask better questions and adjust before a structure no longer suits them.