Australia’s 2026-27 Federal Budget proposes a major change to capital gains tax: replacing the 50% CGT discount with a discount based on inflation, plus a 30% minimum tax on gains from 1 July 2027.

Proposed transitional rules would split gains for assets already held before 1 July 2027. Gains arising before that date would continue to use the current 50% CGT discount, while gains after that date would use cost base indexation and the minimum tax rule.

This calculator helps you model the broad trade-off.

For the broader investor context, read 2026 Federal Budget: What Australian Investors Need to Know. ETF investors may also want our guide to what the 2026 Budget means for ETFs.

How to use the CGT indexation calculator

Enter your purchase price, purchase date, expected sale price, expected sale date, marginal tax rate, CPI assumption, and the asset’s expected value at 1 July 2027 if you already hold it before that date.

The calculator estimates:

• tax under the current 50% CGT discount
• tax under an indexed cost base
• tax with the proposed 30% minimum tax rule
• break-even CPI and annual return assumptions

Important assumptions

This is a simplified modelling tool, not personal tax advice. It assumes a single CGT asset, a simple annual CPI assumption, and no capital losses, transaction costs, Medicare levy effects, income support exemptions, ownership structure differences, or asset-specific concessions.

The proposed rules have not yet been legislated and the final law may differ from the Budget announcement. Before making a sale, restructure, or tax-planning decision, speak with a registered tax agent or qualified adviser.

Sources

• Australian Government Budget 2026-27: Tax reform
• NAB: 2026 Federal Budget - What it means for Individuals