Published: 1 April 2026

Shares Capital Gains Tax Calculator Australia: Your Complete Guide for FY 2025-26

Investing in shares has become increasingly popular among Australians looking to build wealth outside of superannuation and property. Whether you have been buying blue-chip stocks for decades or recently started trading through a low-cost brokerage app, understanding how capital gains tax (CGT) applies to your share portfolio is essential. The Australian Taxation Office (ATO) requires all share investors to report capital gains and losses in their annual tax return, and getting it wrong can lead to penalties and interest charges.

This comprehensive guide explains everything you need to know about calculating capital gains tax on shares in Australia for the 2025-26 financial year. From understanding when CGT applies to your trades, to calculating your tax liability using the 50% discount, and keeping the records the ATO expects, you will learn how to manage your share investments in a tax-effective way. By the end, you will be equipped to handle your share-related tax obligations with confidence.

How Capital Gains Tax Works on Share Investments

Capital Gains Tax is the tax you pay on the profit made when you sell or dispose of shares that have increased in value. In Australia, CGT is not a separate tax. Instead, capital gains are added to your other taxable income for the financial year and taxed at your marginal rate. This means your share profits are combined with your salary, investment income, and other earnings to determine your total tax liability.

A CGT event occurs whenever you sell shares, give them away, or transfer them to another entity. The most common trigger is simply selling shares on the stock exchange. However, other events like transferring shares to a family member, redeeming units in a managed fund, or receiving shares as part of a company restructure can also create CGT obligations. Even if you do not receive cash, the ATO treats these transactions as disposals at market value.

The basic calculation for shares is straightforward: subtract your cost base from your sale proceeds to determine your capital gain. Your cost base includes the purchase price plus brokerage fees and any other acquisition costs. If you sell shares for more than your cost base, you have a capital gain. If you sell for less, you have a capital loss that can be used to offset other gains. Understanding this calculation is the foundation of managing your income tax obligations as a share investor.

CGT Rates on Shares for FY 2025-26

Since capital gains on shares are included in your assessable income, the tax rate you pay depends on your total taxable income for the year. The 2025-26 financial year follows the Stage 3 tax cuts, which provide relief across all income brackets. For share investors, understanding these rates is crucial for estimating the tax impact of your investment decisions.

The 50% CGT discount is one of the most significant benefits available to Australian share investors. If you hold shares for more than 12 months before selling, you can reduce your capital gain by 50% before adding it to your taxable income. For example, if you make a $20,000 profit on shares held for 18 months, only $10,000 is included in your assessable income. This discount effectively halves the tax rate on long-term share investments, making buy-and-hold strategies particularly tax-effective.

Consider a practical example: Michael purchased $50,000 worth of shares in an ASX-listed company in March 2024, paying $500 in brokerage. In June 2025, he sold the shares for $80,000, paying another $500 in brokerage. His cost base is $51,000 ($50,000 + $500 + $500), and his capital gain is $29,000 ($80,000 - $51,000). Since he held the shares for more than 12 months, he applies the 50% discount, reducing his taxable gain to $14,500. If Michael's salary is $90,000, this gain pushes his taxable income to $104,500, and the tax on his share gain would be approximately $4,350 (30% of $14,500).

Calculating Capital Gains on Share Sales

Calculating your capital gains accurately requires attention to detail and good record-keeping. The first step is determining your capital proceeds, which is generally the sale price minus any selling costs like brokerage fees. If you received shares as a gift or inheritance, different rules apply for determining both proceeds and cost base.

Your cost base is more than just the purchase price. It includes the original cost of the shares, plus brokerage fees on purchase, plus certain other costs like stamp duty (rare for modern share transactions) and some holding costs in specific circumstances. Keeping accurate records of all these components ensures you do not overpay tax by understating your true cost base. The ATO may ask for documentation to support your calculations, so holding onto contract notes and brokerage statements is essential.

When you have bought the same shares at different times and prices, you need a method for determining which shares you are selling. The ATO allows two methods: first-in-first-out (FIFO) and specific identification. FIFO assumes you sell your oldest shares first, which may result in higher or lower gains depending on price movements. Specific identification lets you choose which parcel of shares you are selling, giving you flexibility to optimise your tax outcome. Once you choose a method for a particular shareholding, you should apply it consistently.

Capital Losses and Offsetting Gains

Not every share investment results in a profit. When you sell shares for less than your cost base, you make a capital loss. While nobody invests to lose money, capital losses are valuable for tax purposes because they can be used to offset capital gains. This process, known as loss offsetting, can significantly reduce your overall CGT liability.

The ATO requires you to apply capital losses against capital gains in the same financial year before applying the 50% discount. This ordering rule is important because it maximises the benefit of your losses. For example, if you have a $30,000 capital gain and a $10,000 capital loss, you subtract the loss first (leaving $20,000) and then apply the 50% discount (resulting in $10,000 taxable). You cannot apply the discount first and then offset the loss.

If your capital losses exceed your capital gains in a financial year, you can carry the excess losses forward indefinitely to offset future gains. This is particularly valuable for share investors who experience market downturns. Those carried-forward losses remain available until you have gains to offset them against, providing a silver lining to investment setbacks. However, capital losses cannot be used to offset other income like your salary or interest earnings.

Special Rules for Share Investors

Share investments come with some special CGT rules that differ from other assets. Dividend reinvestment plans (DRPs) are common among Australian companies and create multiple CGT events over time. Each time you receive shares instead of cash dividends, you acquire a new parcel of shares with its own cost base equal to the dividend amount. When you eventually sell, you need to account for all these separate parcels, each potentially with different acquisition dates and costs.

Corporate actions like share splits, consolidations, and demergers also have specific CGT implications. A share split (such as 2-for-1) does not create a CGT event but adjusts your cost base per share. Demergers can be more complex, with special rules determining how the original cost base is allocated between the parent and spun-off companies. The ATO often issues class rulings for major demergers to help shareholders calculate their tax position correctly.

For employees who receive shares or options as part of their remuneration, different rules apply. Employee share schemes have their own tax treatment, with some discounts taxed as employment income when received rather than as capital gains when sold. If you participate in an employee share scheme, you will need to track both the employment income component and the eventual capital gain or loss on disposal.

Record-Keeping Requirements for Share Investors

The ATO requires you to keep records of all share transactions for at least five years after you lodge your tax return. For shares you still hold, you need to keep records until five years after you dispose of them. This means some records may need to be kept for decades if you are a long-term investor. Good record-keeping is not just about compliance. It ensures you claim all legitimate deductions and pay the correct amount of tax.

For each share purchase, you should record the date of acquisition, the number of shares bought, the purchase price, and any brokerage or other costs. For sales, record the date of disposal, the number of shares sold, the sale price, and selling costs. If you participate in dividend reinvestment plans, keep records of each reinvestment including the dividend statement showing the amount reinvested and the number of shares received.

Many online brokers provide tax reporting tools that can help simplify record-keeping. These tools often track your cost base, calculate gains and losses, and generate reports for tax time. However, if you use multiple brokers or hold shares in different entities, you may need to consolidate information from various sources. Some investors use dedicated portfolio tracking software to maintain a complete picture of their holdings across all platforms.

How Share Gains Interact with Your Overall Tax Position

Capital gains on shares do not exist in isolation. They are added to your salary, investment income, and other earnings to determine your total taxable income. This means that a substantial share gain can push you into a higher tax bracket, affecting not just your CGT liability but your entire financial picture. Understanding how these pieces fit together helps you make informed decisions about when to sell shares.

Your take-home pay and regular income form the baseline for your tax calculations. When you add capital gains, your total tax liability increases accordingly. This is why timing share sales strategically can make a significant difference. If you are expecting a year with lower employment income, perhaps due to career changes or extended leave, that might be an ideal time to realise share gains. Conversely, if you are already in the top tax bracket, deferring sales could save you money.

Capital gains can also affect other aspects of your tax position. They are included in the income tests for the Medicare levy surcharge, which applies to high-income earners without private health insurance. If you have a HECS-HELP debt, share gains are included in your repayment income calculation and could trigger compulsory repayments. Additionally, large capital gains may affect your eligibility for certain tax offsets and government benefits.

Consider strategies like salary sacrifice to superannuation to reduce your taxable income in years when you realise significant share gains. Concessional super contributions are taxed at 15% within your fund, which is substantially lower than most marginal tax rates. While you cannot contribute shares directly to super, selling shares and contributing the cash proceeds can be a tax-effective strategy. Our Superannuation Calculator can help you explore how additional contributions might reduce your overall tax position.

Summary: Key Takeaways for Share Investors

Understanding capital gains tax on shares is essential for every Australian investor. For the 2025-26 financial year, remember these key points: CGT applies when you sell or dispose of shares at a profit, the 50% discount for assets held longer than 12 months can significantly reduce your tax liability, and accurate record-keeping is crucial for both compliance and optimising your tax outcome.

Capital losses can be used to offset gains and carried forward indefinitely, providing flexibility in your tax planning. Special rules apply to dividend reinvestment plans, corporate actions, and employee share schemes, so understanding the specific treatment of your investments is important. Keep detailed records of all transactions, including dates, quantities, prices, and costs, for at least five years after lodging your tax return.

Finally, consider how share gains interact with your overall tax position. Your marginal tax rate, Medicare levy obligations, and HECS-HELP repayments are all affected by capital gains. Strategic timing of share sales and consideration of strategies like salary sacrifice to superannuation can help you manage your tax burden legally and effectively. If your share portfolio is substantial or your situation is complex, consulting a registered tax agent with investment expertise is highly recommended.