Basis Explained: How It Shapes Smart Investing in Australia (2026 Guide)

In simple terms, your basis is the original value of an asset for tax purposes. It’s what you paid for your shares, property, or other investments, including certain associated costs (like stamp duty or brokerage fees). When you sell, your basis determines how much profit (capital gain) you declare to the ATO.

• Shares: Your basis is typically the purchase price plus brokerage fees.

• Property: It’s the purchase price, plus legal fees, stamp duty, and other acquisition costs.

• Crypto assets: Basis includes the cost of the coin or token, plus transaction fees.

This figure is crucial: your capital gain (or loss) is calculated as the difference between your asset’s sale price and its basis. Get it wrong, and you risk overpaying tax—or worse, facing an ATO audit.

This year, several government tweaks are reshaping how investors calculate and use basis:

• ATO Digital Asset Guidance: The ATO’s 2026 update clarified that every crypto transaction is a potential CGT event. Investors must carefully track basis for each token, especially when swapping between cryptocurrencies.

• Property Record-Keeping Requirements: From July 2026, landlords must use digital property ledgers to record basis-related expenses (like renovations or legal costs), making it easier to justify your basis on sale and avoid disputes.

• Share Portfolio Integration: Major brokers now directly report acquisition costs to the ATO, reducing mismatches and errors in basis reporting for shares.

These changes make accurate, up-to-date records of your basis more important than ever. Gone are the days of rummaging for old paper contracts at tax time—digital records are now the gold standard.

Let’s bring basis to life with a couple of everyday scenarios:

• Jane’s Share Portfolio: Jane bought 1,000 shares of an ASX-listed company in 2022 at $10 each, paying a $30 brokerage fee. Her total basis is $10,030. In 2026, she sells all shares for $15 each, netting $15,000. Her capital gain is $15,000 - $10,030 = $4,970, which she must declare on her tax return.

• Sam’s Investment Property: Sam purchased a Brisbane unit in 2018 for $500,000, with $15,000 in stamp duty and $5,000 in legal costs. His basis is $520,000. After renovating (spending $30,000) and selling the property in 2026 for $650,000, his updated basis is $550,000. His capital gain: $650,000 - $550,000 = $100,000 (before other deductions).

• Mia’s Crypto Journey: Mia bought 2 ETH for $4,000 total, paying a $40 exchange fee. Her basis is $4,040. When she swaps 1 ETH for another token, she must record the current value and her original basis for CGT—even if she never ‘cashed out’ to AUD.

Messing up your basis calculation can mean paying thousands more in tax than necessary—or worse, facing back-payments and penalties if the ATO spots an error. Digital tracking tools and updated broker systems are making it easier, but ultimately, the responsibility sits with you.

• Go digital: Use portfolio management apps or your broker’s reporting tools to track acquisition costs and associated fees.

  • Keep receipts: Scan and save all documentation related to asset purchases, improvements, and sale expenses. The ATO expects electronic records for at least five years after a sale.

  • Review yearly: Don’t wait until tax time. Review and update your basis records after every transaction.

  • Check new rules: Stay alert to ATO guidance and digital reporting changes, especially for property and crypto.

Basis isn’t just a dry tax concept—it’s the foundation for making smarter investment decisions and avoiding costly mistakes. With 2026’s digital-first approach and ATO scrutiny, getting your basis right is non-negotiable. Whether you’re trading shares, holding property, or exploring crypto, build the habit of tracking basis now—your future self (and your accountant) will thank you.

Understanding how basis applies across various asset classes is crucial for Australian investors. Each asset class has unique considerations that can impact your investment strategy and tax obligations.

Shares and Equities

For shares, your basis includes not only the purchase price but also any associated costs like brokerage fees. It's important to keep meticulous records, especially if you reinvest dividends or participate in corporate actions like stock splits or rights issues. These events can alter your basis and affect your capital gains calculations.

• Actionable Tip: Use your broker’s online tools to track changes in your share portfolio. Regularly update your records to reflect any corporate actions.

Real Estate Investments

Real estate basis can be more complex due to the variety of costs involved in purchasing and maintaining a property. These include legal fees, stamp duty, and any capital improvements made to the property. Accurate record-keeping is essential, particularly with the new digital ledger requirements from July 2026.

• Actionable Tip: Consider using property management software to track expenses and improvements, ensuring you have a comprehensive record for tax purposes.

Cryptocurrency

Cryptocurrency transactions are under increased scrutiny by the ATO, with each transaction potentially being a CGT event. The volatile nature of crypto prices means that accurately tracking your basis is essential to avoid unexpected tax liabilities.

• Actionable Tip: Use a dedicated crypto tracking app to automatically log transactions and calculate your basis. This can help you stay compliant with ATO requirements.

As the financial landscape becomes more digital, technology plays a pivotal role in managing your basis effectively. Leveraging the right tools can simplify record-keeping and ensure compliance with evolving regulations.

Digital Record-Keeping

The shift towards digital record-keeping is not just a convenience but a necessity, especially with the ATO’s emphasis on electronic records. Using cloud-based solutions ensures that your records are secure, accessible, and easy to update.

• Actionable Tip: Transition to a cloud-based accounting system that integrates with your investment platforms, allowing for seamless updates and backups.

Automation and AI

Automation and artificial intelligence (AI) are transforming how investors manage their portfolios. Automated tools can help track basis, alert you to changes in tax laws, and even predict potential tax liabilities based on your current portfolio.

• Actionable Tip: Explore AI-driven financial planning tools that offer insights into your investment performance and tax implications, helping you make informed decisions.

What happens if I get my basis wrong?

Incorrect basis calculations can lead to overpaid taxes or penalties from the ATO. It's crucial to maintain accurate records and consult with a tax professional if you're unsure.

How often should I update my basis records?

Ideally, update your basis records after every transaction. Regular reviews, at least annually, can help catch any discrepancies early.

Can I adjust my basis for inflation?

No, basis is not adjusted for inflation in Australia. However, keeping accurate records of all associated costs can help ensure your basis reflects the true cost of your investment.

• Australian Taxation Office (ATO) - Capital Gains Tax
• Australian Securities and Investments Commission (ASIC) - Investing Basics

• Understanding Capital Gains Tax in Australia
• Digital Tools for Modern Investors
• Property Investment Strategies