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How to Separate Personal and Business Property Expenses

Published 26 June 2026 · Last updated 26 June 2026

Quick Answer

To separate personal and business property expenses in Australia, maintain clear records and allocate shared costs accurately. The ATO requires that expenses claimed for business purposes be substantiated with evidence, such as receipts or invoices. Consult Division 40 and Division 43 for relevant deductions. Professional advice ensures compliance and maximises tax efficiency.

Separating personal and business property expenses is crucial for accurate tax reporting and maximising deductions. The Australian Taxation Office (ATO) requires clear substantiation of claimed expenses, which means business owners must maintain precise records and allocate shared costs appropriately. Failing to do so can lead to audit risks and missed deductions.

How to Separate Personal and Business Property Expenses

The key to separating these expenses lies in meticulous record-keeping and proper allocation. For properties used for both personal and business purposes, expenses must be apportioned based on actual usage. This includes utilities, maintenance, and depreciation. The ATO's guidelines under Division 40 (plant and equipment) and Division 43 (capital works) outline how to claim these expenses. Typically, you need to determine the percentage of the property used for business and apply this to the total costs.

A common misconception is that any expense incurred on a property can be fully claimed as a business deduction. The ATO requires evidence that the expense is directly related to business use. For example, if a property is used 40% of the time for business, only 40% of the expenses can be claimed.

How This Works in Practice

Consider a business owner with a home office in a property valued at $900,000 in Melbourne. The home office occupies 20% of the total floor area. Annual expenses include $5,000 in utilities, $2,000 in maintenance, and $10,000 in mortgage interest. Only 20% of these costs can be claimed as business expenses, equating to $3,400. With a marginal tax rate of 37%, this results in a tax saving of $1,258 for the year.

Professional Insight

In our experience, business owners often overlook the importance of maintaining separate accounts for business and personal expenses. One thing we frequently see is a lack of detailed invoices or receipts, which can complicate tax filing. Another common issue is the failure to update usage percentages when business operations change. What most investors don't realise is that even small inaccuracies in apportionment can lead to significant tax discrepancies. Consistent review and adjustment of these allocations are essential.

When Does the Answer Change?

  • Mixed-use properties: If a property is used for both business and personal purposes, the apportionment must reflect the actual use.
  • Post-9 May 2017 changes: For properties acquired after this date, certain depreciation claims for second-hand assets are restricted.
  • Pre-1987 buildings: These properties have different capital works deductions under Division 43.
  • Commercial vs. residential properties: Commercial properties have different depreciation rules compared to residential ones.
  • When Should You Seek Professional Advice?

    Seek professional advice when dealing with complex apportionments or if you're uncertain about the eligibility of certain expenses. A Chartered Quantity Surveyor can provide accurate depreciation schedules, while an accountant can ensure all deductions are compliant with ATO regulations. Personal circumstances, such as changes in property use or tax law updates, also warrant expert consultation.

    What to Do Next

  • Set up separate bank accounts for business transactions to simplify record-keeping.
  • Track and document all expenses with receipts and invoices.
  • Calculate the business use percentage of your property accurately.
  • Review your apportionment regularly to reflect any changes in usage.
  • Consult with a QS and an accountant to maximise deductions and ensure compliance.
  • Stay informed about any changes in tax legislation that may affect your claims.
  • Frequently Asked Questions

    How do I calculate the business use percentage of my property?

    Measure the floor area used for business purposes and divide it by the total property floor area. This percentage is then applied to relevant expenses.

    Can I claim depreciation on a home office?

    Yes, you can claim depreciation on assets used in a home office under Division 40. However, assets must be used for business purposes and not be previously used by another owner post-9 May 2017.

    What records do I need to keep for tax purposes?

    Keep detailed records of all expenses, including invoices, receipts, and a log of business use of the property. This documentation supports your claims in case of an ATO audit.

    Are there any state-specific rules for claiming property expenses?

    While the ATO provides federal guidelines, some states may have additional requirements for certain taxes. Check with local authorities or your accountant.

    How do I report these expenses in my tax return?

    Report business-related property expenses in the 'Deductions' section of your tax return, ensuring you have apportioned them correctly according to business use.

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    Written by Koste Team · Koste Chartered Quantity Surveyors · AIQS Member · RICS Member · TPB Registered · 1300 669 400 · info@koste.ai