A split loan is one loan facility divided into two or more separate portions — usually called splits — where each portion can carry its own interest rate type, repayment style or term. For an investor holding more than one property, splitting is one of the main ways to manage interest rate risk, keep interest-only and principal-and-interest repayments doing different jobs across a portfolio, and keep borrowing organised property by property. A split doesn’t change how much you can borrow or what a property is worth — it changes how the debt behind it is arranged.

Most lenders let you split a loan at setup or at refinance. The most common split is part fixed, part variable, but a split can just as easily separate an interest-only portion from a principal-and-interest one, or line up with different properties inside the one facility.

What exactly is a “split”, and how is it different from having several separate loans?

A split lives inside one loan approval — one facility, subdivided into sub-accounts that each behave like their own mini-loan for rate and repayment purposes, but still sit under a single agreement with the lender. That’s a different question to whether several properties share the same security.

When a lender uses more than one property as combined security for a single loan (or a group of linked loans), that’s called cross-collateralisation — a lending structure where two or more properties back one loan or a set of linked loans, rather than each property securing its own stand-alone loan. Linking properties as combined security this way can make it harder to sell, discharge or refinance any one property in isolation, because the lender typically needs to review the whole linked position first.

Splitting and cross-collateralising are separate decisions that often get folded into the same “how do I structure my portfolio” conversation. An investor can have one split loan sitting on cross-collateralised security, or several entirely stand-alone loans — each one itself split into fixed and variable portions. Which combination suits a given portfolio is exactly the kind of question a mortgage broker or licensed adviser is best placed to work through with you, property by property.

Why do portfolio investors split between fixed and variable rates?

A fixed portion locks in an interest rate for a set period, so repayments on that part of the debt don’t move even if market rates do. A variable portion moves with the lender’s rate settings, which usually track broader interest rate conditions.

As at July 2026, the RBA’s cash rate target sits at 4.35%, held at the Reserve Bank’s June meeting after rising through the first half of the year. On the RBA’s own lending statistics, investor loans have generally carried a modest premium over owner-occupier loans — around 0.2 percentage points on average as at May 2026, across both outstanding and new lending. That’s a description of where rates have sat, not a forecast of where they’re going — nobody can tell you whether fixing now would turn out cheaper than staying variable, and this guide doesn’t try.

What a fixed/variable split does is let you hedge that uncertainty rather than resolve it: part of the portfolio’s repayments stay predictable regardless of what happens next, while the rest keeps the flexibility — extra repayments, redraw, an offset account — that a fully fixed loan usually restricts.

Feature	Typical fixed portion	Typical variable portion
Repayment amount	Set for the fixed term	Moves with rate changes
Extra repayments	Often capped or restricted	Usually unlimited
Redraw / offset access	Limited or unavailable	Commonly available
Rate exposure	Protected for the fixed term	Full exposure, either direction
Cost to exit early	A break cost may apply	Generally none

Lender terms differ, so treat this as a general shape rather than any one product’s terms.

How does a split help balance interest-only and principal-and-interest repayments?

Interest-only (IO) repayments cover only the interest charged, so the loan balance doesn’t shrink over the IO period; principal-and-interest (P&I) repayments pay down some of the balance as well. Investors sometimes split a portfolio so one property (or one portion of a loan) sits on IO for near-term cash flow, while another sits on P&I to build equity faster.

There’s no current numeric cap on IO lending from APRA. Between 2017 and 2019, APRA did ask ADIs to limit new interest-only lending to 30% of new residential mortgage lending as a temporary supervisory measure — APRA then announced its removal from December 2018, phased across lenders rather than on one single date. As at July 2026, APRA’s current guidance instead expects each lender to manage IO risk through its own portfolio limits, to keep IO periods “of limited duration, particularly for owner-occupiers”, and to assess serviceability against the actual principal-and-interest repayment period once IO ends — not against the lower IO repayment itself.

That serviceability assessment sits underneath every split, whatever the mix. APRA’s prudential standard requires ADIs to apply an interest rate buffer of at least 3.0 percentage points over a loan’s rate, and expected rental income is generally shaded by a minimum of 20% in the lender’s calculations. Neither figure changes because a loan is split — the buffer and the rental haircut apply to the loan as a whole, and to your total position across a portfolio, not portion by portion.

Does splitting a loan change what interest you can claim as a tax deduction?

Tax outcomes depend on your circumstances — speak with a registered tax agent before acting.

As at July 2026, current law lets a landlord claim a deduction for the full amount of deductible rental expenses — including interest on borrowings — against rental income and other income such as salary, where expenses exceed rental income; if other income isn’t enough to absorb the loss, it carries forward to the next income year. That’s the mechanic behind “negative gearing.” Splitting a loan doesn’t change this on its own — what matters for deductibility is what the borrowed money was actually used for, not which split or sub-account it sits in. The general rule is that interest is only deductible to the extent a loan was used to produce assessable income, and mixing private and investment borrowing inside the same account is exactly what makes that apportionment harder to work out cleanly. That’s a commonly cited reason investors keep investment borrowing in its own split, or its own loan altogether, separate from money drawn for private purposes.

Since this guide was first published, the government enacted a change that matters here. From the 2027-28 income year, a new quarantine rule applies: residential rental deductions that exceed residential rental income will no longer be usable against salary or other income — they’ll only be usable against residential capital gains or carried forward against future residential rental income. Interests acquired before 7:30pm AEST on 12 May 2026 are grandfathered under the current treatment.

New residential dwellings are meant to be exempt from the quarantine, but the detailed definition of what qualifies still depends on a ministerial instrument that hadn’t been made as at this update — so this guide doesn’t state where that line sits. Our guide to cash flow positive versus negatively geared property walks through both the current settings and the 2027-28 change in more depth.

How does loan-to-value ratio and security interact with a split?

Lenders Mortgage Insurance (LMI) is usually payable once the amount borrowed exceeds 80% of a property’s value — this benchmark applies generally, with nothing published to suggest a different trigger or a different premium scale for investment loans versus owner-occupier ones. LMI protects the lender, not the borrower, if the loan defaults.

Where this interacts with splitting is at the security level rather than the split itself. A single split loan facility still sits behind whatever security backs it — one property, or several if the facility is cross-collateralised. If several properties are linked as combined security, a shortfall in equity on one property can affect the whole facility’s position, and untangling a single property later generally means the lender reviewing the remaining linked debt and security first. Keeping each property on its own stand-alone (non-cross-collateralised) loan — split however suits that property — is one way investors avoid that entanglement, at the cost of managing more separate facilities.

What does setting up or changing a split cost?

A few costs are worth weighing before splitting a loan or changing an existing split:

• Break costs. Exiting or reducing a fixed portion before the fixed term ends can trigger a break cost, generally tied to how interest rates have moved since the rate was fixed. The amount depends on the lender, the remaining term and rate movements at the time — this guide doesn’t estimate one, because no general figure applies across lenders.
• Extra account fees. Some lenders charge a fee per split or per account, on top of the loan’s usual fees. This varies by lender and product.
• Complexity. More splits means more sub-accounts to track, more statements, and more decisions if you later want to consolidate, refinance or restructure.

None of these costs are fixed or universal enough to state as a figure here — they’re exactly the kind of detail a mortgage broker can quote against your actual lender and product.

How does ownership structure interact with a split loan strategy?

The same split loan mechanics sit differently depending on who — or what — holds the property. An individual is assessed personally on rental income and expenses under their own marginal tax rate. A company holds the asset in its own right, with company profits and losses dealt with at the company level.

A discretionary or family trust generally has its net income taxed in the hands of the beneficiaries presently entitled to it, in proportion to their entitlement. A self-managed super fund (SMSF) sits under additional superannuation-law tests on top of ordinary lending and tax rules — including a sole purpose test (the fund’s investments must be maintained for retirement or death benefits) and limits on in-house assets. No structure is ranked above another here — each carries materially different consequences, and no government page recommends between them.

Superannuation rules are complex and penalties for breaches are significant — seek advice from a licensed financial adviser before making SMSF decisions.

What should you weigh before choosing a split for your portfolio?

There’s no single “right” split ratio, and this guide isn’t going to hand you one. Factors that typically matter:

• How much repayment certainty you want against how much flexibility (extra repayments, redraw, offset) you’re willing to give up for it
• Whether an interest-only or principal-and-interest repayment shape fits your cash flow and how a lender will assess your serviceability
• Whether keeping each property’s loan separate (avoiding cross-collateralisation) matters more to you than the convenience of one combined facility
• What a break cost could look like on a fixed portion, given how long you expect to hold that property
• How your ownership structure — individual, company, trust or SMSF — interacts with any of the above

A mortgage broker or licensed adviser can model these against your actual portfolio and lender options — this guide sets out the factors, not a recommendation. If you’re still weighing whether geared property investment suits you at all, our guide to property investment in Australia is a reasonable place to start.

Is there a way into property investing that skips the loan question altogether?

Split loans, IO/P&I balancing and cross-collateralisation are all questions that come with gearing — borrowing to buy. Fractional investing sidesteps the loan side of that equation: it’s a way of buying an economic interest in a specific residential property alongside other investors, without arranging your own mortgage for it. Our guide to what fractional property investment is covers the mechanics. As at July 2026, MyBrix’s NestEgg product sets a minimum contribution of $100 a month, with contributions accumulating until they cover a whole Brix where the monthly amount falls short of the current price.

The short version

A split loan divides one facility into portions — commonly fixed and variable, sometimes interest-only and principal-and-interest — so a portfolio can carry both rate certainty and flexibility at once. Splitting is a separate decision from cross-collateralisation, which links more than one property as combined security. Neither changes APRA’s underlying serviceability tests (the interest rate buffer, the rental income haircut), and neither changes how interest deductibility works — that still comes down to what the borrowed funds were used for, which is exactly why many investors keep investment and private borrowing apart.

Break costs, account fees and added complexity are the main trade-offs to weigh, alongside how your ownership structure and your broader appetite for certainty versus flexibility line up. A mortgage broker or licensed adviser, working from your actual numbers, is the right place to turn a set of factors into a structure.