How the Calculator Works
Enter your total loan amount and choose how to divide it:
- Fixed portion (amount and fixed rate)
- Variable portion (amount and current variable rate)
The calculator outputs the repayment on each portion separately and the combined monthly total. You can adjust the split ratio to compare 50/50 against 60/40 or 70/30 and see how the blended repayment changes.
Why Perth Borrowers Use Split Loans
The fixed vs variable decision is one of the most debated in home lending – and the honest answer is that no one can reliably predict rate movements with enough accuracy to get it right every time. A split loan sidesteps the need to call the direction perfectly by exposing the borrower to both outcomes simultaneously.
The benefits of each component:
Fixed portion:
- Repayments are locked for the fixed term (typically one to five years), providing budget certainty
- Not affected by RBA cash rate increases during the fixed period
- Useful when rates are expected to rise and budget discipline is important
Variable portion:
- Repayments reduce automatically when the RBA cuts rates
- Unlimited extra repayments permitted on most variable products
- Full offset account access typically available on the variable portion
- No break costs when making lump sum payments or refinancing the variable component
Choosing the Split Ratio
There is no universally correct split ratio. The right balance depends on your risk tolerance, the size of your offset savings, and your cash flow requirements.
| Borrower Profile | Suggested Split Consideration |
| Budget-sensitive, wants maximum certainty | Higher fixed portion (60% – 80%) |
| Holds significant offset savings | Higher variable portion to maximise offset benefit |
| Expects to make large extra repayments | Higher variable portion to avoid fixed-rate caps |
| Plans to sell within three to five years | Smaller fixed portion or avoid fixing altogether |
| Large loan ($800,000+) in rising rate environment | Split can meaningfully stabilise monthly repayments |
The Offset Account Interaction
Most fixed-rate home loans in Australia do not permit a full offset account. Some lenders offer a partial offset on fixed products; others offer none. The variable portion of a split loan is where the offset account generates its saving.
For a borrower with $60,000 in savings and a $700,000 loan split 50/50 ($350,000 fixed, $350,000 variable), the offset account can only work against the $350,000 variable portion. At 6.5%, $60,000 in offset against $350,000 variable generates an interest saving of approximately $3,900 per year. Against the full $700,000 loan it would save approximately $3,900 per year regardless – but the fixed portion prevents offset applying there.
If holding a large offset balance is important, weighting the split toward variable (or staying fully variable) preserves the full benefit. The Home Loan Offset Calculator can model this trade-off directly.
Fixed-Rate Extra Repayment Caps
Making extra repayments on the fixed portion is subject to the lender’s annual cap – usually $10,000 – $30,000 per year without incurring break costs. The variable portion has no such restriction. For borrowers who plan to make significant extra repayments from surplus income or windfalls, structuring more of the loan as variable preserves the ability to accelerate repayment freely.
If receiving a large bonus or inheritance during a fixed period that exceeds the cap, parking the surplus in an offset account on the variable portion achieves the same daily interest reduction on that portion without triggering break costs.
Split Loans in a Changing Rate Environment
In 2025, the RBA began cutting the cash rate, with variable rates falling across the market as multiple reductions flowed through to borrowers. Borrowers who were fully fixed during this period did not benefit from lower repayments. Borrowers on split loans received rate relief on their variable portion while retaining stability on the fixed portion.
The same logic applies in reverse: during the 2022–2023 rate rise cycle, borrowers who had fixed a portion of their loan were partially protected from rising repayments on that fixed component while their variable portion increased with market rates. Neither outcome is universally better – but the split reduces the magnitude of either direction’s impact.
How a Split Loan Compares to a Fully Fixed or Fully Variable Loan
| Feature | Full Fixed | Split Loan | Full Variable |
| Rate certainty | Maximum | Partial | None |
| Rate rise protection | Full | Partial | None |
| Rate cut benefit | None | Partial | Full |
| Offset account | Usually not available | On variable portion | Usually available |
| Extra repayments | Capped | Capped on fixed; unlimited on variable | Unlimited |
| Break costs | Apply to full balance | Apply to fixed portion only | None on variable |
| Flexibility to refinance | Restricted | Partially restricted | Full |
Pairing This Calculator With Others
Once you’ve determined your preferred split ratio, use the Loan Comparison Calculator to compare a split loan structure against a fully variable or fully fixed alternative across the same loan amount and term. The Introductory Rate Loan Calculator is useful if you’re considering using an introductory rate product as your variable component.
Frequently Asked Questions
1. Can I choose any split ratio, or are there restrictions?
Most lenders allow any split, though some set minimum amounts for each portion (e.g. a minimum of $50,000 per component). Check the lender’s product rules before nominating a split below that threshold.
2. Can I change the split ratio after the loan is set up?
Not easily without refinancing. Once the fixed period begins, the fixed portion is committed for the term. You can make changes to the variable portion more freely. If you want to adjust the fixed/variable balance, this typically requires refinancing the whole loan when the fixed term expires.
3. Are there two separate loan accounts with a split loan?
Yes. Most lenders establish two separate loan accounts – one for the fixed portion and one for the variable portion. Each has its own rate, repayment, and features. They are usually grouped under a single loan package.
4. What happens when the fixed portion expires?
When the fixed term ends, that portion reverts to the lender’s standard variable rate unless you choose to re-fix. This is an important review point – the revert rate may not be competitive. Your broker can advise on whether to re-fix, convert to variable, or refinance entirely at that stage.
5. Is a split loan more expensive than a fully variable loan?
Sometimes. Lenders may charge an annual package fee that applies across both portions, and the fixed rate itself may carry a slightly higher rate than the best available variable product. The blended cost depends on the specific products chosen. Use the Comparison Rate Calculator to compare the true cost across structures.
Structure Your Loan to Match Your Situation
A split loan is not right for every borrower – but for many Perth homeowners who want both stability and flexibility, it offers a practical middle path that pure fixed or pure variable can’t provide. Central Lending Solutions helps borrowers across Perth model the real cost of different loan structures and find lenders whose split loan products suit their income, savings, and risk profile. Call (08) 9201 8570 to discuss your options, or explore our home loan refinance and fixed rate loans pages.