2026 Budget CGT Calculator
There are now two ways of applying the proposed post-1-July-2027 CGT rules to an asset you already own — and they turn on how the asset is valued at 30 June 2027. Compare a market valuation against the proposed daily-indexation method side by side, with the current rules as a reference. Change any number to recalculate instantly.
Method 2 needs no valuation — it estimates this value from your purchase and sale figures.
Method 1 — your 2027 valuation
$1,768,607 after tax
Method 2 — daily indexation
$21,093 more than method 1
Current rules (reference)
50% discount on the whole gain
The proposed daily-indexation method (method 2) works out $21,093 more than the market-value method — 2.1% of your gross gain.
| Method 1 | Method 2 | |
|---|---|---|
| Value at 30 June 2027 used to split the gain | $1,700,000 | $1,624,289 |
| Taxable pre-2027 gain (after 50% discount) | $350,000 | $312,144 |
| Indexed cost base at sale | $1,857,673 | $1,774,940 |
| Post-2027 gain (indexed, no discount) | $142,327 | $225,060 |
| Estimated tax at the flat 47% rate | $231,393 | $252,486 |
| After-tax proceeds | $1,768,607 | $1,747,514 |
Both methods are estimates of the proposed post-1-July-2027 treatment: the gain up to 30 June 2027 keeps the 50% discount, and the 30 June 2027 value becomes a CPI-indexed cost base for the later gain, which gets no discount. Tax is applied at a flat 47% (top marginal rate plus Medicare levy) to the taxable gain; the current-rules figure is a reference calculated the same way. Based on the assumptions entered.
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How this CGT calculator works
- 1
Your gain is split at 30 June 2027
Under the proposed rules, growth up to 30 June 2027 keeps the 50% CGT discount, while the value at that date becomes a new cost base for everything after. Both methods below apply exactly this treatment — they differ only in what that 30 June 2027 value is.
- 2
Method 1 — you supply a market valuation
The enacted approach uses the asset's actual market value at 30 June 2027, which means obtaining a valuation at the transition date. You enter your estimate of that value and the calculator splits the gain there.
- 3
Method 2 — the value is estimated from your growth
The proposed alternative needs no valuation. It assumes the asset grew at one constant daily rate from purchase to sale, and runs that rate forward to 30 June 2027 to estimate the split value. A smooth growth path can land above or below a real valuation — which is exactly what moves the tax.
- 4
Both methods are taxed the same way
Half the pre-2027 gain plus the whole post-2027 gain (above the CPI-indexed cost base) is taxed at a flat 47% — the top marginal rate plus the Medicare levy. The calculator shows the current rules alongside as a reference. Based on the assumptions entered.
Worked example: a $1,000,000 asset sold in 2030
Suppose you bought an asset for $1,000,000 on 1 July 2020, it is worth $1,700,000 at 30 June 2027, and you sell it for $2,000,000 on 30 June 2030, with CPI at 3%.
| Method 1 — market value used to split the gain | $1,700,000 |
| Method 2 — estimated value at 30 June 2027 | $1,624,289 |
| Tax under method 1 (market value) | $231,393 |
| Tax under method 2 (daily indexation) | $252,486 |
| Tax under the current rules (reference) | $235,000 |
| Method 2 costs MORE by | $21,093 |
In this scenario the asset outgrew its smooth trend by 30 June 2027, so the daily-indexation method estimates a lower split value than the $1.7M valuation. That pushes more of the gain into the undiscounted post-2027 slice and costs about $21,000 extra. When an asset has grown slower than its long-run trend by 2027, the same mechanism flips and method 2 comes out cheaper — neither method is always dearer.
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 only sale proceeds above that indexed figure are taxed on the later growth. Growth up to 30 June 2027 keeps the current treatment. There are now two methods for working out that 30 June 2027 value — this calculator estimates both.
What's the difference between method 1 and method 2?
Method 1 uses the asset's actual market value at 30 June 2027, which means obtaining a valuation at the transition date. Method 2 — the proposed alternative — needs no valuation: it assumes the asset grew at one constant daily rate from purchase to sale and runs that rate forward to 30 June 2027 to estimate the split value. Both then tax the gain identically; only the split value differs.
Which method works out cheaper?
Neither is always cheaper. A higher 30 June 2027 value pushes more of the gain into the discounted pre-2027 slice and lowers the tax; a lower value does the opposite. If your asset had outgrown its long-run trend by mid-2027, method 2's smooth-growth estimate lands below a market valuation and typically costs more — and vice versa. The calculator estimates both on your numbers.
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 — however it is determined — 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. It works the same way under both methods.
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 — under both methods. Only growth after that date moves to the indexed, no-discount treatment.
Why does the calculator use a flat 47% tax rate?
47% is the top marginal rate plus the 2% Medicare levy — the rate a top-bracket taxpayer pays on an additional dollar of taxable gain. Using it keeps the two methods directly comparable without modelling your full income position. If your income sits in a lower bracket, the dollar figures shrink but the comparison between the methods moves the same way. Estimates only, based on the assumptions entered.
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