Deductibility follows what your borrowed money bought, not the house securing it. How portability, settlement and the moves around them decide whether your split survives the move.
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Deductibility is decided by what the borrowed money was used for and whether that use produces assessable income. The security your lender holds is a credit decision, not a tax one:
Interest is deductible under section 8-1 of the Income Tax Assessment Act 1997 to the extent it is incurred in gaining or producing assessable income. The Australian Taxation Office (ATO) applies a use test, which looks at where the borrowed funds went. Money drawn from your investment split and sent to a broker to buy an exchange traded fund portfolio meets that test. Money drawn from the same split to cover a transfer duty bill does not, and the ATO rules on interest deductions require a split used for both purposes to be apportioned for as long as the loan exists.
Your lender took a mortgage over your home because residential property is the cheapest security available to you, not because the house generates the deduction. A split used to buy shares is deductible whether it is secured by your current home, your next one or an investment property. Selling the security does not sell the purpose, though it does force the loan to be repaid or moved, and that is where the risk sits.
A new loan taken out to repay an existing loan generally takes on the character of the loan it replaces. Borrow $250,000 from an incoming lender and send it straight to the outgoing lender to clear a $250,000 investment split, and the new borrowing is treated as continuing the old one. The principle lets the strategy survive a change of lender, a change of security or both. It holds only where the new funds genuinely repay the old deductible borrowing and the amounts line up. Draw $400,000 to clear a $250,000 split, and the extra $150,000 stands or falls on its own purpose.
Tracing is the documented path from the loan split to the asset, and settlement is the point where it is most easily lost. The evidence worth holding includes the payout figure on the old split, the discharge authority, the new loan schedule showing the matching split, the settlement statement and the bank record showing funds moving between the two on the same day. Careful debt recycling record-keeping turns a plausible position into one your accountant can substantiate years later.
Two mechanisms carry an investment split across a move, and the difference is whether the original loan contract survives. Both can preserve deductibility. They differ in cost, timing and how much has to line up on the day:
Portability, which most lenders document as substitution of security, swaps the property behind an existing loan without repaying the loan. The account number, the balance, the split structure and the original purpose all carry across untouched, so there is nothing to re-establish and nothing to trace beyond the substitution itself. It also avoids break costs on a fixed-rate split, which can be worth more than the fee it attracts. Substitution does not lift the limit, so any additional borrowing for the new home is a separate application assessed on its own merits.
Where portability is unavailable, the alternative is discharging the existing loans and writing new ones. Deductibility can still hold, provided the new investment split is drawn for the specific purpose of repaying the old one and the funds move directly between lenders at settlement. The split has to be replicated at the incoming lender as its own account with its own balance, never folded into the home loan, with the opening balance matched to the payout figure on the old split.
Settlements that fall weeks or months apart take substitution off the table, because there is no new security to substitute on the day the old one is released. Bridging finance can cover the purchase side, though bridging drawn to buy a home is private borrowing and does not become deductible by sitting alongside a split that is. Renting in between is cleaner, but it usually means the investment split is repaid at the sale, and reinstating it later is a fresh borrowing judged on its own purpose.
Substitution is a policy question, and policies differ by lender and by product. The conditions that typically apply include:
These conditions are a general guide only. Policy, fees and timing vary between lenders and products, and your own application will be assessed on its merits at the time.
Most deductions lost in a move are not lost because of the sale. They are lost in what happens to the money in the days around it:
Discharging a property repays every loan secured by it, the investment split included, unless substitution or a matching refinance has been arranged first. Once that split is repaid, the deductible borrowing no longer exists. The portfolio still does, and it keeps producing income, but there is no loan attached to it to claim interest on. Rebuilding the deduction afterwards means borrowing and investing again, which usually involves selling assets and triggering capital gains tax, so the answer is to avoid the repayment in the first place.
Redraw is new borrowing, and its purpose is judged at the moment you draw it. Pulling funds back out of an investment split to top up the deposit on the next home makes that portion private, and the split becomes a mixed-purpose account that has to be apportioned for the rest of its life. Repayments on a mixed account reduce both purposes proportionally, so the private portion cannot be cleared first. The redraw contamination trap catches people mid-strategy, and a settlement is a common place to walk into it.
Incoming lenders often propose one clean loan over the new property, and it looks tidier on the approval. Consolidating a deductible split into a non-deductible home loan destroys the separation the structure depends on, and the resulting account carries a single blended balance with no way to identify which dollars were which. Two separate splits at the new lender usually cost little or nothing extra and keep the arithmetic obvious to you, your accountant and the ATO.
Surplus cash from a sale has to sit somewhere between settlements, and where it sits matters. Money deposited into an offset account attached to a split reduces the interest charged without repaying the loan or changing its purpose. Money deposited into the split itself repays deductible debt, and drawing it back out later is a fresh borrowing assessed on whatever it funds. The offset is the holding pattern; the split is not.
Loan documents get signed under time pressure, and split names end up as whatever the lender's system defaulted to. Months later nobody can tell from the statements which account replaced which. Confirming the account structure, the split labels and the opening balances in the week after settlement takes little effort and removes an argument you would otherwise have to reconstruct from memory.
The mechanics stay constant, though the consequences do not. Each option leaves the deductible side untouched while doing different things to the non-deductible side:
Buying up means a bigger home loan and the same investment split. The deductible proportion of your total debt falls, sometimes sharply, even though the deductible amount itself has not moved. That is not the strategy failing; it is a larger house. It does mean a longer runway, because there is more non-deductible debt available to recycle over the years ahead, and a heavier repayment obligation to carry in the meantime. Serviceability is assessed across both loans, and the investment split counts against your capacity like any other debt.
Downsizing can clear the non-deductible loan outright, which is the outcome the strategy was aiming at. The question then becomes what to do with the surplus, and the reflex to pay down the investment split deserves a pause. Repaying it removes the deduction permanently, and redrawing that money for anything private does not bring it back. Holding it costs real interest, which the deduction offsets but never fully returns, so the answer turns on the portfolio, your marginal rate and what else the cash is needed for.
Crossing a state border has no effect on deductibility, though it often forces a refinance. Substitution needs the same lender on both sides, and an interstate purchase can run into different settlement conventions, different transfer duty rules and a purchase timetable that will not align with the sale. Queensland contracts, for example, commonly run to a shorter standard settlement period than New South Wales. Where substitution cannot work, the discharge-and-refinance route remains available.
Some households keep the old home, rent it out and buy the next one. Once the former home is genuinely available for rent, interest on the loan originally used to buy it can generally become deductible, because the asset that borrowing funded is now producing assessable income. The trap is in the sequence. Paying that loan down over the years and then redrawing the balance to fund the new home creates private borrowing secured against an income-producing property, and no amount of restructuring afterwards changes what the money was used for.
Deductibility itself is unaffected by the 2026 Federal Budget measures, though from 1 July 2027 net rental losses on an established home acquired after 7:30pm AEST on 12 May 2026 can generally be offset only against residential rental income or gains from residential property, with any excess carried forward. Homes held or under contract before that time keep the current treatment, so your original contract date is the first thing your accountant will ask for.
The example below is illustrative and built on the assumptions listed, not a forecast or a promise of any result:
Assumptions only. Rates, duty, selling costs and tax rates vary by lender, state and individual circumstances, and your own figures will differ.
Total debt is $670,000, of which $250,000 is deductible and $420,000 is not. That puts the deductible share at roughly 37%. The portfolio funded by the split sits outside the property altogether and is untouched by the sale.
Sale proceeds after costs come to $1,115,000. Where the split is ported or refinanced, $420,000 clears the home loan and $695,000 goes towards the purchase, leaving $815,000 to borrow against the new home alongside the $250,000 split that carried across. Where the split is repaid at settlement instead, $670,000 is cleared, $445,000 is available and $1,065,000 is borrowed as a single home loan.
| Item | Split ported or refinanced | Split repaid and reborrowed |
|---|---|---|
| Home loan, non-deductible | $815,000 | $1,065,000 |
| Investment split, deductible | $250,000 | Nil |
| Total debt | $1,065,000 | $1,065,000 |
| Deductible interest at 6.20% | About $15,500 a year | Nil |
| Indicative tax effect at 39% | About $6,000 a year | Nil |
Total debt is identical in both columns. The only difference is which side of the ledger the same $250,000 sits on, and on these assumptions that difference is worth roughly $6,000 a year in tax while the split stays in place. Over a long strategy it compounds, because those refunds are what accelerate the home loan.
Debt recycling relies on three professionals staying in step, and a sale is the moment that coordination gets tested:
Establish what each split is, what it funded and what it owes before the property goes to market. A split that has drifted into mixed purpose over the years is better identified now than discovered at settlement, when there is no time left to do anything about it.
Substitution is a policy question with a short answer, and it shapes the settlement dates you agree to in the contract. Ask it before the contract is signed, not after, because a 30-day sale and a 60-day purchase cannot be reconciled once both are binding.
Simultaneous settlement is a conveyancing outcome as much as a lending one. Your solicitor or conveyancer negotiates the dates, your lender confirms what it will accept, and your broker sits between the two so neither is working from an assumption about the other.
Your accountant or registered tax agent is the one who signs off on whether the deduction survives, so they need the proposed structure in advance, not a shoebox of statements in July. Give them the payout figures, the intended split balances at the new lender and the settlement timetable while all three can still be changed.
A move changes cash flow, buffers and the amount of risk you can comfortably carry, particularly on an upgrade. Your financial adviser is the one to review whether the portfolio, the emergency buffer and the timeframe still fit while a larger non-deductible loan is being serviced, and whether any part of the strategy should be paused.
Loan documents are the last opportunity to get the separation right without an amendment. Confirm the split names, the account numbers and the opening balances before signing, then check them again on the first statement after settlement.
The strategy you set up is more portable than it feels when the sale board goes up. A change of address alters nothing about what your borrowed money bought, and those assets keep working right through the transaction. The exposure is narrow and procedural, sitting almost entirely in what happens to one loan split on one day.
Households move mid-strategy every year and come out the other side with the same deductible balance, a different address and a portfolio that never noticed the transaction.
If your home is going on the market and the investment split has to survive the move, Kingfisher Finance Group can confirm what your lender allows on substitution and map the split structure at the incoming lender. Reach out while both contracts are still negotiable.
Book a free call →Not by itself. What ends the deduction is the split being repaid at settlement with nothing continuing it, because the deductible borrowing stops existing while the portfolio it funded carries on. Ask your lender about substitution before you sign a contract, since that is the point at which the outcome is still yours to choose.
Often, yes, through substitution of security, which many lenders call portability. Expect a valuation on the incoming property, a loan-to-value ratio inside policy, identical borrowers on both titles and a fee usually in the low hundreds. The limit cannot be increased under a substitution, so any extra borrowing for the new home is a separate application.
Substitution generally stops being an option, because no new security is available on the day the old one is released. The usual paths are bridging finance for the purchase, or a refinance in which the incoming lender advances a matching split that repays the old one directly. Both need arranging in advance, since neither can be applied retrospectively.
Repaying it removes deductible debt permanently, and drawing the money back out later for a private purpose does not restore the deduction. There are situations where reducing total borrowings is the right call, particularly where new repayments would stretch your cash flow. It is a decision for your accountant and financial adviser with your full position in front of them.
No. The existing split and the portfolio it funded continue as they are. What changes is capacity: the investment split counts against your serviceability like any other liability, so the larger home loan is assessed on top of it, at an interest rate at least three percentage points above the actual rate.
Interest on the loan used to buy that home can generally become deductible once it is available for rent. The evidence that matters is the date the property was advertised, the rental appraisal and the balance of the original loan on that date, because the deduction is limited to the borrowing that bought the property, not to what it is worth now.
Your accountant or registered tax agent gives the tax position, your financial adviser reviews the portfolio and buffers, and your broker builds the loan structure the other two are relying on, which means confirming whether substitution is available and documenting the payout so the trail holds.
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