2026 Budget CGT Calculator
See how the proposed 2026 budget changes could affect the capital gains tax on an asset you already own — pre-2027 growth keeps the 50% discount, post-2027 growth moves to an indexed cost base. Change any number to recalculate instantly.
Tax under current rules
$225,350 from the sale
Tax under 2026 budget
$3,607 less
| Tax with no capital gain | $22,252 | |
| Pre-2027 gain (50% discount) | $700,000 | $154,850 |
| Post-2027 gain (cost base indexed to $1,857,673) | $142,327 | $66,893 |
| Total tax attributable to the sale | $221,743 |
Tax is estimated on FY2027-28 resident rates plus 2% Medicare levy, applied to your other income with and without the gain. Post-2027 gains use a CPI-indexed cost base with no discount and a 30% minimum rate. Based on assumptions entered.
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How this CGT calculator works
- 1
Your gain is split at 30 June 2027
The growth from your purchase price to the asset's value at 30 June 2027 is treated under the current rules; growth after that date falls under the proposed budget treatment. You supply both values, so the split reflects your own estimates.
- 2
Pre-2027 growth keeps the 50% discount
Half of the gain accrued up to 30 June 2027 is added to your other income and taxed at the FY2027-28 resident rates plus the 2% Medicare levy — the same way a discounted capital gain is taxed today.
- 3
Post-2027 growth is indexed, with no discount
The 30 June 2027 value becomes a new cost base, uplifted by your CPI estimate for each year until sale. Only sale proceeds above that indexed figure are taxed — but with no 50% discount, and a 30% minimum rate applies to this portion.
- 4
The two systems are compared side by side
The calculator totals the tax attributable to the sale under the current rules and under the proposed rules, using the incremental method — your tax with the gain minus your tax without it — so bracket effects are captured. Based on the assumptions entered.
Worked example: a $1,000,000 asset sold in 2030
Suppose you bought an asset for $1,000,000, it is worth $1,700,000 at 30 June 2027, and you sell it for $2,000,000 on 30 June 2030, with $100,000 of other income and CPI at 3%.
| Tax under the current rules | $247,602 |
| Pre-2027 gain (50% discount preserved) | $700,000 |
| Indexed cost base at sale | $1,857,673 |
| Post-2027 gain (indexed, no discount) | $142,327 |
| Tax under the proposed 2026 budget | $243,995 |
| The proposed rules cost LESS by | $3,607 |
In this scenario the indexed cost base removes three years of inflation-only growth from the taxable gain, which outweighs losing the 50% discount on the post-2027 portion — so the proposed system comes out slightly cheaper. With different growth, timing or income the sign flips.
Figures are estimates based on the assumptions entered — change any input in the calculator above to see your own numbers.
CGT and the 2026 budget — common questions
What does the 2026 budget change about capital gains tax?
Under the proposal, growth in an asset's value after 30 June 2027 would no longer receive the 50% CGT discount. Instead, the asset's value at 30 June 2027 becomes a new cost base that is indexed by CPI, and the tax on that later growth is subject to a 30% minimum rate. Growth up to 30 June 2027 keeps the current treatment.
What is an indexed cost base?
Indexation uplifts the cost base by inflation (CPI) each year, so only growth above inflation is taxed. In this calculator the 30 June 2027 value is compounded by your CPI estimate over the years to sale, and only the sale proceeds above that indexed figure count as the post-2027 gain.
Does the 50% CGT discount disappear?
Not for growth you have already had. The proposal preserves the 50% discount for the gain accrued up to 30 June 2027 — the calculator taxes that portion under the current rules. Only growth after that date moves to the indexed, no-discount treatment.
What is the 30% minimum rate?
If the income tax attributable to the post-2027 portion of the gain works out below 30% of that gain, a top-up applies to bring it to 30%. For higher incomes the ordinary marginal rate already exceeds 30%, so the top-up is often zero.
Can the new rules work out cheaper than the current ones?
Yes, in some scenarios. Indexation removes inflation-only growth from the taxable gain, which can outweigh losing the 50% discount on the post-2027 portion — the worked example on this page shows one such case. Whether it does for you depends on the assumptions entered, which is exactly what the calculator estimates.
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