Basis Explained: How It Shapes Smart Investing in Australia (2025 Guide)

When it comes to investing, whether you’re buying shares, property, or crypto, there’s one term that quietly shapes your profits, tax bills, and even your strategy: basis. In 2025, as Australia’s tax and investment rules evolve, understanding your asset basis is more important than ever.

What Is Basis—and Why Should Australian Investors Care?

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.

2025 Policy Shifts: What’s New for Basis in Australia?

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

• ATO Digital Asset Guidance: The ATO’s 2025 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 2025, 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.

Real-World Examples: Getting Basis Right (and Wrong)

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 2025, 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 2025 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.

Tips to Stay on Top of Basis in 2025

• 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.

Conclusion: Basis—Your Key to Smarter, Safer Investing

Basis isn’t just a dry tax concept—it’s the foundation for making smarter investment decisions and avoiding costly mistakes. With 2025’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.