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TAX TRAP

The $10,000 Redraw Mistake: How Your Offset Account Is Quietly Killing Your Tax Deduction

16 APRIL 2026·11 MIN READ·BY LODGEY
One tap on the redraw button can cost you tens of thousands in tax over the life of your loan. Move $50K out of your investment loan for a new car and that portion of the loan becomes non-deductible forever — or until you fully repay the loan. Your offset account is fine. Your redraw is not. This is the most misunderstood line in the mortgage-meets-tax world.
Is All It Takes
1 redraw
A single personal-purpose withdrawal taints the loan
Typical Cost
$30K+
Over a 20-year remaining loan on a $50K tainted portion
The Ruling
TR 2000/2
Purpose of funds — not security — determines deductibility
TL;DR — THE RULE IN 5 LINES
  • Interest on a loan is deductible only if the borrowed funds are used for an income-producing purpose.
  • A redraw is treated as a new borrowing — the purpose test applies to whatever you spent it on.
  • An offset accountis separate from the loan; moving money in and out doesn't affect deductibility.
  • A single personal-purpose redraw permanently splits the loan into deductible and non-deductible portions.
  • The fix isn't free — you can split the loan at the bank to stop future leakage, but historical interest is lost.
01

The Rule Nobody Reads: It's the Purpose, Not the Security

The ATO's framework for when loan interest is deductible sits in Taxation Ruling TR 2000/2 and the seminal Federal Court case Domjan v FCT. Both confirm the same principle with almost ruthless simplicity:

"It is not the original purpose of the loan that determines tax deductibility, but rather how the borrowed funds are currently being used."

The implications are sharper than most investors realise:

  • A loan secured against your investment property is not automatically deductible.
  • A loan secured against your own home can be fully deductible — if you used the funds to buy shares, an investment property, or any other income-producing asset.
  • Once money's drawn from a loan, what it gets spent on determines whether the interest on that portion is deductible. Forever.
The Domjan lesson. Mrs Domjan argued that because her bank requiredher home to be used as security, the associated costs (including insurance) should be deductible. The court said no. The security doesn't change the deduction test — only the purpose of the borrowed funds does.
02

The Same $50K, Two Very Different Outcomes

The clearest way to see the trap is to trace a single $50,000 withdrawal through both paths. In one, your loan is untouched and fully deductible. In the other, your loan is permanently split.

DIAGRAMSAME $50K, TWO PATHS
Offset path
✓ Deductibility safe
Loan$500,000
Investment purpose
Deposit $50K savings
Offset$50,000
Reduces interest charged
Withdraw $50K for new car
Offset$0
Back to starting position
Loan still$500,000
100% deductible — no change to the loan
Redraw path
✗ Loan tainted
Loan$500,000
Investment purpose
Pay $50K extra off the loan
Loan$450,000
Available redraw: $50K
Redraw $50K for new car
Loan$500,000
Split: $450K investment + $50K personal
Deductible now90%
$50K interest portion is lost — for the life of the loan

The key difference: money in an offset stays your money — the loan balance (and interest calculation) never changes. Money in a redraw is loan repayment — taking it back out is a fresh borrowing, and its deductibility is judged by what you spent it on.

03

Put Your Numbers In

The damage isn't just the interest itself — it's the lost tax deduction compounded over every year of the loan you have left. Slide your numbers into the calculator to see what a single redraw actually costs.

INTERACTIVELOAN TAINT CALCULATOR
$500,000
$50,000
6.0%
22 years
Your loan balance after the redraw$500,000
DEDUCTIBLE · $450K
DEDUCTIBLE %
90%
INTEREST LOST / YEAR
$3,000
EXTRA TAX / YEAR
$1,110
TOTAL COST OVER 22 YR
$24,420
Over the remaining 22 years, your personal redraw costs you $24,420 in extra tax. The fix is to split the loan or refinance — the sooner, the less you leak.

Simplified model — assumes flat interest on the tainted portion and a static marginal rate. Real loans amortise, so the annual cost declines slightly over time, but the cumulative order of magnitude holds. Doesn't account for Medicare levy or CGT implications.

04

Three Redraws That Catch People Out

The most common and most expensive mistake. You've built up $80K of redraw in your investment loan, you use it as a deposit for your new PPOR. That $80K is now a personal-purpose loan (against your own home). Interest on $80K at 6% = $4,800 p.a. of lost deduction. At a 37% marginal rate, that's $1,776 p.a. of extra tax — for every year of the loan.
Private purpose, full stop. Even if you put the redrawn money back into the loan later, the taint is established at the draw point and the interest on that portion is non-deductible for the life of the loan.
You redraw $100K intending to buy shares. You sit on it in the bank account for three months, then decide against it and pay it back. The ATO's position is that between draw and repayment, those funds weren't producing income. The interest for those three months is non-deductible.
Putting an investment-purpose redraw into an offset account to "keep it separate" doesn't preserve deductibility. The ATO's position is that once you mix the funds with other money, you've broken the nexus to the income-producing purpose. Draw straight into a dedicated sub-account instead.
05

How to Unwind a Tainted Loan

If you've already made a personal redraw, you can't retroactively reclaim the deductions you've lost. What you can do is stop the leakage from here and make future interest cleaner to apportion. Four practical moves, in order of priority:

01
Ask your bank for a loan split
Most major lenders will split an existing loan into two sub-accounts at no cost. You keep the investment-purpose portion in one, the personal-purpose portion in the other, and each has a separate statement. Apportionment becomes automatic — no annual tracing required. This is the single highest-leverage move.
02
Pay down the personal portion first
Any extra repayments should go to the non-deductible sub-account. You're saving after-tax interest on the personal portion, which has the highest real cost per dollar. The deductible portion can sit — the government is effectively subsidising that interest.
03
Refinance cleanly if splitting isn't offered
Some smaller lenders don't offer same-bank splits. Refinancing to a new lender who does gives you a clean start — open two facilities from day one, each tied to a clear purpose. Break costs on the old loan are still deductible if the property continues to earn income.
04
Keep redraws investment-only going forward
Once you have a clean structure, use redraws only for further investment purposes (extra shares, additional property costs, renovations on the income-producing property). Everything else routes through offset or a separate personal facility.
Don't try to fix it with creative accounting.The High Court shut down "linked loan" schemes in Commissioner of Taxation v Hart (2004). If the split is manufactured purely to maximise deductions — with no genuine commercial rationale — Part IVA anti-avoidance rules apply. Use real sub-accounts with real separate balances.
06

Six Misconceptions Worth Unlearning

MisconceptionReality
"The loan is against my rental, so the interest is deductible."Security is irrelevant. What the borrowed funds were used for — and are currently being used for — is the only test.
"I'll just put it back and it'll fix itself."Paying the redrawn amount back doesn't undo the taint. The interest for the period the funds were personal remains non-deductible.
"Offset and redraw are basically the same thing."They look similar in your banking app but their legal structure is different. Offset = your money reducing interest. Redraw = extra repayment that you can pull back out as a new borrowing.
"Storing investment funds in offset keeps them deductible."No. Mixing draws with other money breaks the nexus. Investment redraws should go straight to the investment purchase, never parked.
"The ATO won't notice."The ATO gets full loan data — redraws and balances — from all major banks. The property management data-matching program cross-references this against rental income claims.
"I can just claim 100% and work it out later."Claiming 100% when the loan has a known personal component is an audit trigger. The ATO prefers a small over-claim found voluntarily to one it has to dig out.
07

FAQ

The questions our agent sees most often from investors discovering they've already tapped redraw.

Yes. The deductibility of each dollar of interest is judged by what the matching dollar of borrowed funds was used for. Non-deductible dollars stay non-deductible until repaid in full and cleanly.

Only as the personal balance reduces. Every extra repayment goes against the non-deductible sub-account first (under ATO apportionment rules), gradually shrinking the tainted slice until the loan is back to pure investment purpose.

No — only the portion you drew. The rest of the loan remains deductible. But every subsequent redraw (even small ones) compounds, and once you have several untracked micro-draws, the apportionment becomes a nightmare.

Different scenario — here you're converting a PPOR loan into an investment loan. Interest on your existing loan for the old home becomes deductible from the date it starts producing rent. But any redraw you took out before renting it to fund the new home is personal — deductibility on that portion stays blocked.

Only the lender can split a loan — you can't fabricate sub-accounts in your records. Call your bank or broker. Most major lenders offer it as a standard product with no or low fees.

Not directly. An offset reduces the interest you're charged on the loan, which reduces both your cost and your deduction by the same amount. The benefit is cash-flow / after-tax — you keep your savings liquid without sacrificing loan deductibility.

The Bottom Line

Redraw looks like a feature. For a tax-aware investor it's a trap — one tap for a personal expense and a slice of your loan becomes non-deductible for the life of the loan. The fix is almost always boring: ask the bank to split the account, keep each sub-account tied to a single purpose, and route personal spending through an offset account or a separate personal facility.

If you've already done it — don't panic, don't try to paper over it, and don't invent creative loan-tracing arguments. Call your bank about a split, direct extra repayments to the personal portion, and lodge a voluntary amendment if you realise past years' claims were over-stated. The ATO is dramatically more forgiving of taxpayers who correct themselves.

This article is general information only and does not constitute tax advice. Interest deductibility interacts with property use, trust and company structures, cross-collateralisation, and Part IVA. Get independent advice from a registered tax agent for your specific circumstances.

BEYOND THE REDRAW TRAP
What other deductions are you leaving on the table?

Loan taint is one category. Depreciation schedules, borrowing costs, land tax, CGT cost base — the calculator totals everything you're likely missing and tells you how fast Lodgey pays back.

See my total savings →

Sources

  • Australian Taxation Office — TR 2000/2: Deductibility of interest on refinancings and mixed-purpose loans
  • Domjan v FCT (2004) 56 ATR 1218 — security versus purpose for interest deductibility
  • Commissioner of Taxation v Hart (2004) 217 CLR 216 — Part IVA and linked-loan arrangements
  • HLB Mann Judd — "How to protect your investment loan deductions"
  • BAN TACS — "Mixed Purpose Loans Explained"
  • Aintree Group — "Warning for those redrawing investment loans"
  • Passive Investing Australia — "Redraw vs Offset"
  • r/AusFinance and r/fiaustralia community threads on split-loan mechanics
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