CGT Calculator: How the Proposed Capital Gains Changes Could Affect Your Sale
The 2026–27 Federal Budget proposes the biggest change to capital gains tax in 25 years. For sales on or after 1 July 2027, the 50% CGT discount would be scrapped and replaced with cost-base indexation plus a 30% minimum tax on your real gain. This tool shows, side by side, what your tax could look like under the current rules versus the proposed rules — so you can plan the timing of a property, share or business sale before the goalposts move.
- Compare current 50% discount vs proposed indexation + 30% floor
- Works for property, shares and business asset sales
- Stacks the gain on your other income for a realistic tax figure
- Shows the dollar difference and your effective tax rate
- Runs entirely in your browser — nothing is sent anywhere
- Built by a Registered Tax Agent in Sydney
Capital Gains Tax — Current vs Proposed Rules
Enter a gain once and see both outcomes. All figures are estimates for guidance only.
How the calculator works
Enter your sale. Cost base, expected sale price, how long you have held the asset, and your other income for the year.
We model both rule sets. Current 50% discount versus the proposed indexed cost base with a 30% floor rate, each stacked on your other income.
See the gap. The dollar difference and effective tax rates show whether timing your sale before 1 July 2027 is worth discussing.
The two rule sets, side by side
| Feature | Current rules (until 30 June 2027) | Proposed rules (from 1 July 2027) |
|---|---|---|
| Discount on long-held assets | 50% CGT discount for individuals and trusts on assets held over 12 months | 50% discount removed; replaced with cost-base indexation for inflation |
| Minimum tax | None — taxed at your marginal rate on the discounted gain | A 30% floor rate applies to the real (indexed) gain |
| Top effective rate | About 23.5% (47% × 50%) | Up to 47%, with 30% as the minimum |
| Assets held since before Sept 1985 | Exempt (pre-CGT) | Growth from 1 July 2027 onwards becomes taxable |
| Main residence | Generally exempt | No change proposed — still exempt |
| Small business CGT concessions | Available if eligible | Retained — not changed by this measure |
Rates modelled: 2025–26 resident marginal rates (0 / 16 / 30 / 37 / 45%) plus the 2% Medicare levy. Indexation is estimated using your chosen inflation rate compounded over the holding period. The main residence exemption and small business CGT concessions are not applied automatically — speak to us if they apply to you.
Frequently asked questions
Are these changes actually law yet?
No. They were announced in the 2026–27 Federal Budget and are proposed to start for CGT events on or after 1 July 2027. Legislation has not been passed and the detail can still change — particularly the treatment of small and start-up businesses, which is still under consultation. Do not make a sale decision on this tool alone.
What is “indexation” and why does it matter?
Instead of halving your gain, the proposed rules lift your cost base by inflation over the time you held the asset, then tax the “real” gain above that. For assets with a low starting cost — like a business built from scratch — indexation gives little relief, so the outcome can be much higher than today’s 50% discount.
What is the 30% minimum tax?
Under the proposal, a floor rate of 30% applies to your real capital gain. If your marginal rate on the gain would be below 30%, you would still pay 30%. If it is above 30%, your higher marginal rate applies.
Does the main residence exemption still apply?
Yes. The Budget did not propose changes to the main residence exemption, and the small business CGT concessions are retained. This tool does not apply those automatically, so your actual position may be lower than shown if they apply.
Should I rush to sell before 1 July 2027?
Not necessarily. Timing is only one factor — market conditions, your income in the year of sale, available concessions and your longer-term plans all matter. The point of this tool is to start that conversation early, while you still have flexibility.
How accurate is the figure?
It is a careful estimate using published marginal rates and a simplified Medicare levy. It does not model the Medicare levy surcharge, capital losses, partial-year residency, or every concession. Treat it as a guide to the size of the gap, not a final tax calculation.
Thinking about selling? Let’s model it properly.
If the gap looks significant, the timing and structure of your sale could be worth thousands. Book a 30-minute chat and we’ll run your real numbers, factor in any concessions, and map out your options before the rules change.
Book a 30-minute chat Explore tax planning
Built by Ramy Hanna, Principal of Trinity Accounting Practice — Registered Tax Agent, Fellow IPA, TIA & NTAA.
Trinity Accounting Practice · 159 Stoney Creek Road, Beverly Hills NSW 2209 · trinitygroup.com.au
Liability limited by a scheme approved under Professional Standards Legislation.
