Unadjusted Basis Explained for Australian Investors in 2026

The 'unadjusted basis' of an asset is its original cost before taking into account any subsequent adjustments like depreciation, capital improvements, or deductions. In simple terms, it’s what you initially paid for the asset, plus certain acquisition costs. For most Australians, this comes into play when calculating capital gains tax (CGT) on property, shares, or business assets.

• Example: If you bought a rental property in Brisbane for $750,000 in 2021 (including legal fees and stamp duty), your unadjusted basis is $750,000.

• Why it matters in 2026: With the ATO increasing data-matching programs this year, accurately reporting your asset basis can help you avoid compliance issues and penalties.

Several regulatory changes in 2026 have sharpened the focus on basis calculations:

• ATO Digital Asset Reporting: The ATO now receives more detailed transactional data from banks and brokers, especially for property and cryptocurrency trades. Any errors in basis reporting can be quickly flagged.

• CGT Discount Rules: While the 50% CGT discount still applies to assets held for 12+ months, recent proposals to tighten eligibility criteria mean that your unadjusted basis must be well documented to claim the full discount.

• Instant Asset Write-Off Changes: For small businesses, the $20,000 instant asset write-off has been extended, but the initial purchase price (unadjusted basis) is critical in determining eligibility.

Staying updated with these policies can save you both time and money when preparing your 2026 return.

The concept isn’t just for accountants—it affects everyday investors and business owners. Here are a few scenarios:

• Property Sales: When you sell an investment property, you start with your unadjusted basis to calculate your capital gain or loss. Forgetting to include initial costs (like legal fees) can artificially inflate your taxable gain.

• Share Investments: For shares bought over multiple tranches, each purchase’s unadjusted basis must be tracked to accurately report CGT when you sell.

• Business Equipment: If you purchase machinery, your depreciation schedules and any eventual asset sale calculations rely on the correct unadjusted basis.

• Crypto Transactions: With cryptocurrency, every buy has its own unadjusted basis, and 2026’s reporting standards require meticulous record-keeping.

To avoid headaches at tax time and ensure compliance, consider these strategies:

• Keep Complete Records: Store contracts, invoices, and settlement statements for all asset purchases.

• Use Digital Tools: Leverage property or investment management software that tracks acquisition costs and calculates basis automatically.

• Regular Reviews: Schedule an annual check-in to ensure your basis records match your current holdings, especially after making improvements or receiving corporate actions (like share splits).

Whether you’re a first-time investor or running a growing business, understanding unadjusted basis gives you a firmer grip on your tax obligations and investment returns. With the ATO’s enhanced scrutiny in 2026, accurate basis tracking isn’t just good practice—it’s essential. By staying on top of your records and understanding the rules, you’ll make tax time a breeze and keep more of your gains where they belong: in your pocket.

Understanding unadjusted basis is not just theoretical; it has real-world applications that can significantly impact your financial outcomes. Here are some practical examples tailored for Australian investors:

Example 1: Residential Property Investment

Consider an investor who purchased a residential property in Sydney for $900,000 in 2022, including $30,000 in legal fees and stamp duty. The unadjusted basis is $930,000. In 2026, the investor sells the property for $1.2 million. To calculate the capital gain, the investor subtracts the unadjusted basis from the sale price, resulting in a gain of $270,000. Properly documenting the initial costs ensures the investor can accurately report this gain to the ATO.

Example 2: Share Portfolio Management

An investor buys 1,000 shares of an ASX-listed company at $10 each in 2023, with a brokerage fee of $500. The unadjusted basis for these shares is $10,500. In 2026, the investor sells the shares at $15 each. The capital gain is calculated by subtracting the unadjusted basis from the total sale proceeds of $15,000, resulting in a gain of $4,500. Accurate tracking of purchase costs and brokerage fees is crucial for correct CGT reporting.

Example 3: Small Business Asset Purchase

A small business owner purchases a delivery van for $50,000 in 2024, with additional costs of $5,000 for registration and insurance. The unadjusted basis is $55,000. When the van is sold in 2026 for $40,000, the owner needs to calculate the loss or gain based on the unadjusted basis. This precise calculation helps in claiming the correct deductions and ensuring compliance with ATO regulations.

To effectively manage your unadjusted basis, consider the following actionable steps:

Maintain Detailed Records

• Document Everything: Keep all purchase receipts, invoices, and financial statements related to your assets. This documentation is crucial for accurate tax reporting and compliance.
• Organise Digitally: Use digital tools to scan and store documents securely, ensuring easy access and retrieval during tax season.

Leverage Technology

• Investment Software: Utilise software solutions that automatically track asset purchases and calculate unadjusted basis, reducing manual errors.
• Regular Updates: Ensure your software is updated with the latest tax regulations and reporting requirements to stay compliant.

Consult Professionals

• Financial Advisors: Engage with financial advisors who specialise in Australian tax law to optimise your investment strategies.
• Tax Accountants: Work with tax accountants to ensure your unadjusted basis calculations align with ATO standards and to maximise your tax efficiency.

What is the significance of unadjusted basis for CGT?

The unadjusted basis is critical for calculating capital gains tax, as it represents the initial cost of an asset. Accurate basis calculation ensures you pay the correct amount of tax on your gains.

How does the unadjusted basis affect my tax returns?

A precise unadjusted basis helps in determining your capital gains or losses, impacting the amount of tax owed. Errors in basis calculation can lead to overpayment or penalties from the ATO.

Can I adjust the unadjusted basis for improvements?

Yes, capital improvements can be added to the unadjusted basis, increasing the initial cost and potentially reducing your taxable gain when the asset is sold.

• Australian Taxation Office (ATO) - Capital Gains Tax
• Australian Securities and Investments Commission (ASIC) - MoneySmart
• Reserve Bank of Australia (RBA) - Financial Stability

By integrating these strategies and resources, Australian investors can confidently manage their unadjusted basis, ensuring compliance and optimising their financial outcomes. For more insights, visit our Investing Basics and Tax Strategies pages.