Split Mortgages: Hedging Your Bets on Interest Rates

When your mortgage comes up for renewal, the temptation is to find the "best" rate and put everything on it. One-year fixed looks attractive? Lock in the whole lot. Three years seems like a good hedge? Same approach. This all-or-nothing mentality feels decisive, but it is actually one of the riskier ways to structure your home loan.

A split mortgage divides borrowing across terms or rate types, so portions may reprice at different times. The outcome still depends on future rates, fees, repayment rights and the borrower’s budget; no structure works well in every scenario.

Why Single-Term Loans Are Riskier

Imagine you have a $600,000 mortgage and you fix the entire amount for one year at 5.5%. When that year ends, you need to refix everything at whatever rates are available. If rates have jumped to 7.5%, your entire mortgage just got significantly more expensive in one hit. Your monthly payments could increase by $700 or more.

Now imagine the same mortgage split into three portions: $200,000 at one year, $200,000 at two years, and $200,000 at three years. When the first portion expires, only a third of your mortgage is exposed to the new rates. The impact on your budget is more gradual and manageable, giving you time to adjust.

With one expiry date, the full fixed balance may be repriced together. Splitting spreads expiry dates, but can also leave different portions at different prices and does not guarantee a better overall result.

Common Split Strategies

There is no single "correct" way to split a mortgage. The right approach depends on your circumstances, goals, and comfort with uncertainty. Here are some common strategies homeowners use:

• Ladder strategy: Split evenly across one, two, and three-year terms. Each year, one portion rolls over. Over time, you end up with a perpetual ladder where something always comes due annually.
• Core and flexible: Fix the majority for a longer term (stability) and keep a smaller portion floating or short-term fixed (flexibility for extra payments and rate movements).
• Weighted split: Put more on the term you prefer, less on others. For example, 50% on two years, 25% on one year, 25% on three years.
• Fixed plus revolving: combine fixed and revolving portions, after checking the revolving portion’s repayment, redraw, interest, fee and limit terms.

The Role of Floating and Revolving Credit

Including a floating or revolving credit portion in your split is not just about rates. It is about maintaining financial flexibility that fixed portions cannot provide.

Extra-repayment allowances, break charges and redraw rights vary by loan contract. Check how the lender treats lump sums on each fixed, floating or revolving portion before relying on access or penalty-free repayment.

• Park an emergency fund in revolving credit; it reduces interest while remaining accessible
• Absorb irregular income like commissions or freelance earnings
• Make large repayments when funds are available without penalty concerns
• Cover unexpected expenses without resorting to higher-interest credit

Fixed, floating and revolving pricing changes by lender and offer. Compare the current rate, fees, repayment rights and total cost for the amount placed in each portion; there is no universal floating percentage that suits most homeowners.

Building Your Split Strategy

Rather than trying to predict rates, build your split around your actual situation:

If payment certainty matters, compare how each available fixed term affects the budget and total cost, including what happens when that portion expires.

If extra repayments or redraw matter, compare the written flexibility, fees and limits of the available fixed, floating and revolving options.

A ladder is one possible structure, but it does not ensure a balanced result: some portions may reprice higher or lower, and the borrower must manage multiple expiry dates.

Managing Your Split Over Time

A split mortgage requires more attention than a single-term loan. You will have multiple expiry dates to track, multiple decisions to make, and potentially multiple portions with different interest rates and repayment amounts.

Keep a calendar of when each portion expires. Your lender will send reminders, but staying ahead allows you to research options and negotiate rather than reacting at the last minute.

At each rollover, resist the urge to just tick a box and move on. Ask yourself:

• Has my financial situation changed since I set up this structure?
• Do I have money I want to pay off this portion before refixing?
• Should I adjust my split to better match my current circumstances?
• Are there better rates available from other lenders?

At expiry, ask for the lender’s current written options and charges; whether a change avoids break or variation fees depends on the contract and transaction.

When Not to Split

Split mortgages are not for everyone. There are situations where a simpler structure might serve you better:

If you are planning to sell within a couple of years, having multiple fixed portions creates more complexity around break fees. A short single fix or predominantly floating structure may be cleaner.

If managing multiple portions and dates feels overwhelming, the administrative burden might not be worth it for you. Some homeowners genuinely prefer the simplicity of one rate, one term, one repayment amount.

If your mortgage is relatively small, the practical benefits of splitting diminish. The interest rate differences between portions matter less when the dollar amounts involved are modest.

Getting Help With Your Structure

A licensed mortgage adviser can explain available loans, costs and scenarios. Ask which lenders and products they considered, how they are paid and why a recommendation may suit the stated needs.

A good adviser will ask about your income stability, your plans for the property, your tolerance for payment changes, and your likelihood of making extra payments. They will use your answers to recommend a structure rather than just chasing the lowest headline rate.

Compare the structure against the household budget, likely repayment needs, written fees and several rate scenarios. Splitting does not guarantee protection or savings; personal suitability is a regulated-advice question.