Many tradies who've built solid income want to start investing — typically in property, shares, or both. But mixing investment debt with business and personal finances creates complexity around which interest is deductible and which isn't. Get it right and investment debt is one of the most powerful wealth-building tools available. Get it wrong and you're either overclaiming or missing legitimate deductions.

This guide covers how investment loan interest deductions work for tradies, how to structure investment borrowings correctly, and the relationship between investment leverage and your overall financial position.

The Golden Rule: Interest Deductibility

The ATO allows interest on loans to be deducted when the loan is used to produce assessable income. This is the foundation of all investment interest deductibility.

Deductible:

  • Interest on a loan used to buy a rental property (rental income is assessable)
  • Interest on a loan used to buy shares (dividends are assessable)
  • Interest on a margin loan used to buy income-producing investments
  • Interest on a loan used to buy into a managed fund paying distributions

Not deductible:

  • Interest on your home mortgage (your home doesn't produce assessable income)
  • Interest on a personal car loan
  • Interest on a holiday loan
  • Interest on a loan that was originally investment-purpose but funds were withdrawn for personal use

The purpose test: The ATO looks at what the money was actually used for, not what the loan was called. If you took a "business loan" but used the funds to renovate your bathroom, the interest is personal — not deductible.

Investment Property Loans for Tradies

Buying an investment property with a mortgage is the most common investment structure for Australian tradies. The interest on the investment mortgage is fully deductible against rental income.

What You Can Claim on an Investment Property Loan

Interest on the loan: The primary deduction. If you pay $28,000 in mortgage interest per year on an investment property loan, that's a $28,000 deduction — reducing your assessable income by that amount.

Loan establishment costs: Borrowing costs (application fees, valuation fees, mortgage insurance, stamp duty on the loan) are deductible over the lesser of 5 years or the loan term.

Interest on borrowed funds for property costs: If you borrowed to pay the stamp duty on the investment property purchase, that interest is also deductible.

Redraw for investment purposes: If you redraw on an investment loan to fund repairs or improvements to the investment property, the interest on the redrawn amount is deductible. But if you redraw for personal use, the interest on that portion is not.

Negative Gearing: The Full Picture

An investment property is "negatively geared" when the deductible costs (interest, rates, insurance, depreciation, repairs) exceed the rental income. The loss is deductible against other income — including your trade business income or wages.

Example:

  • Tradie earns $130,000 from trade business
  • Investment property: $24,000 rent received, $36,000 in deductible costs
  • Net investment loss: $12,000
  • Taxable income: $130,000 − $12,000 = $118,000
  • Tax saving (at 39% marginal rate): $4,680/year

Negative gearing is not a strategy by itself — it's a side-effect of owning an asset that costs more than it earns short-term, with the expectation of long-term capital growth. The tax saving helps carry the asset while it grows.

Positive gearing (rental income exceeds costs) means the net income is assessable — you pay tax on the surplus, but you're also putting cash in your pocket each year.

The Traps with Mixed-Purpose Loans

This is where many tradies get into trouble. If you mix personal and investment borrowings in the same loan account — or redraw on a loan for personal purposes — you lose deductibility on the personal portion.

The Classic Tradie Trap: Redrawing on the Home Loan

A tradie has a home mortgage that's been partially paid down. They want to invest in shares. Instead of getting a separate investment loan, they redraw $80,000 from their home loan.

The problem: The home loan is primarily a personal loan (your home doesn't produce income). When you redraw, you're borrowing for investment purposes — but it's impossible to cleanly separate the investment portion from the personal portion, especially as you make repayments.

The ATO applies interest tracing rules. If you can clearly identify that the $80,000 redraw went directly to investment purposes and you kept it completely separate, the interest on that $80,000 may be deductible. But mixed-purpose loans make this hard to prove and easy to get wrong.

The correct approach: Use a separate loan account for investment borrowings. If you're buying an investment property, get a standalone investment mortgage. If you're borrowing to buy shares, use a dedicated margin loan or a separate redraw specifically for investment, tracked separately in your records.

Investment Property Loans: Structuring for Optimal Tax

Interest-Only vs Principal and Interest

For investment properties, many accountants recommend interest-only (IO) loans for the investment debt during the investment phase. This maximises the interest deduction in each year and keeps the non-deductible repayments (principal) lower.

Meanwhile, your home mortgage (non-deductible) should be paid down as aggressively as possible with any surplus cash.

The logic: Every dollar of deductible investment debt carrying interest at (say) 7% net of 39% tax costs you effectively 4.27%. Every dollar of non-deductible home loan debt at 7% costs you the full 7%. Pay down the expensive debt, maintain the cheap (post-tax) debt.

Offset Accounts: Where the Magic Happens

An offset account linked to your home mortgage works like a savings account — the balance reduces the outstanding loan balance for interest calculation. Your take-home pay goes into the offset account, reducing home loan interest immediately.

Example:

  • Home loan balance: $450,000
  • Money in offset: $40,000
  • Interest calculated on: $410,000

The offset account reduces your non-deductible home loan interest at the full cost of money. Meanwhile, your investment loan (separate) remains at its full balance, maintaining full deductibility.

This structure — IO investment loan, P&I home loan with offset — is one of the most common optimisation strategies for tradie property investors and is entirely legitimate with the ATO.

Shares and Margin Loans

For tradies who prefer shares to property, a margin loan allows you to borrow against a portfolio of shares to buy more shares. The interest is deductible as investment interest.

How margin loans work:

  • You invest $50,000 in an ASX ETF portfolio
  • The margin lender lends you an additional $50,000 (at 50% LVR)
  • You now have $100,000 invested
  • You pay interest on the $50,000 borrowed (typically 7–10% p.a.)
  • Dividends and franking credits offset some of the interest cost
  • Capital growth on the full $100,000 benefits from leverage

The margin call risk: If the portfolio falls below the lender's LVR threshold, they issue a margin call — you must top up cash or sell assets. This happened widely during COVID-19 and the 2022 market correction. Margin loans amplify gains but also amplify losses.

For most tradies building wealth, a non-leveraged share portfolio (simple ETFs bought without borrowing) is lower risk and still highly effective over time. Margin lending is a more sophisticated tool suitable for tradies who understand the risk and have strong cash flow to manage margin calls.

Tax Treatment of Investment Income

Rental Income

Rental income from an investment property is fully assessable in the year received. Net rental income (income minus deductions) is added to your other income and taxed at your marginal rate.

If you're negatively geared: The net loss reduces your other taxable income. For a tradie in the 39% marginal rate, each dollar of negative gearing saves 39 cents.

Dividend Income

Dividends from Australian shares are assessable income. However, franked dividends come with franking credits — a tax offset equal to the company tax already paid on the profits.

Example:

  • You receive a $700 dividend from BHP
  • The dividend is 100% franked
  • Franking credit attached: $300 (at 30% company tax rate)
  • You include $1,000 in your assessable income (gross dividend)
  • You receive a $300 tax offset
  • If your marginal rate is 39%, tax on $1,000 = $390, minus $300 offset = $90 net tax
  • Effective tax rate on the dividend: 9% — much lower than your marginal rate

For tradies in high marginal rate brackets, fully franked Australian shares are particularly tax-effective.

Capital Gains on Investment Assets

When you sell an investment property or shares, capital gains apply. If you've held the asset for more than 12 months, the 50% CGT discount applies — you include only half the capital gain in your assessable income.

Example:

  • Tradie buys investment property for $400,000
  • Sells 8 years later for $700,000
  • Capital gain: $300,000
  • After 50% discount: $150,000 added to assessable income
  • Tax at 39% marginal rate: $58,500
  • Effective tax rate on the $300,000 gain: 19.5%

This is why property investment is popular for high-income tradies — the CGT rate on growth after the 50% discount is significantly lower than their income marginal rate.

Deducting Investment Loan Costs: What Counts

Beyond interest, these investment loan costs are deductible:

  • Loan interest — Yes — Full deduction annually
  • Application/establishment fee — Yes — Amortised over loan term or 5 years
  • Stamp duty on the loan — Yes — Amortised over loan term
  • Annual loan fee — Yes — Full deduction in year incurred
  • Lenders Mortgage Insurance (LMI) — Yes — Amortised over 5 years
  • Mortgage broker fee (if charged) — Yes — Amortised over loan term
  • Stamp duty on the property purchase — No — Added to cost base (reduces CGT)

Getting the Structure Right Before You Borrow

The most important time to think about loan structure is before you sign the documents, not after.

Questions to answer before taking an investment loan:

  1. Is this loan entirely for investment purposes — or am I mixing in personal borrowing?
  2. Will this loan sit completely separate from my home mortgage and business borrowings?
  3. Do I have an offset account on my home loan to reduce the non-deductible interest?
  4. If I'm using equity in my home, am I splitting the loan into separate accounts for clear tracing?
  5. Have I confirmed the interest tracing position with my accountant before drawing down?

Get your accountant involved before you take investment debt. An hour of advice up-front is worth months of untangling later.

Frequently Asked Questions

Q: Can I borrow from my business to invest personally?
If you operate through a company, lending money from the company to yourself for personal investment is a Division 7A issue — it must be structured as a complying loan with market interest rates and minimum repayments. Speak to your accountant before doing this.

Q: Can I claim interest on a loan I used to buy a car I also use for investments (driving to inspect properties)?
No — a car loan is not deductible based on how you use the car. Vehicle expenses for investment property inspections can be claimed separately as investment expenses (at the ATO's per-km rate or using a logbook), but the car loan interest is not deductible.

Q: I bought shares in my company's name — is the interest on the share purchase loan deductible by the company?
If the company borrowed to buy shares that produce assessable income (dividends), the interest is deductible to the company. The company's 25% tax rate applies, which may be less efficient than the 50% CGT discount available to individuals for assets held 12+ months. Individual share ownership is often more tax-efficient for capital growth assets.

Q: What records do I need to keep for investment interest deductions?
Keep all loan statements, bank statements showing interest charges, and records of what the borrowed funds were used for. For mixed-purpose loans, keep a clear trail showing how investment funds were separated and used. Keep records for 5 years after the last tax return claiming the deduction — or 5 years after the asset is sold, whichever is later.