CGT comparison calculator: old rules vs 2026 budget framework

How the calculator works

The calculator runs three scenarios in parallel each time you change an input:

Scenario A: Old rules (existing Division 115 framework). Applies the 50 percent CGT discount under section 115-25 of the ITAA 1997 if the asset is held longer than 12 months. Tax = gain × 0.5 × marginal_rate. Used as the counterfactual reference point.

Scenario B: New rules (whole holding). Applies indexation from the purchase quarter (if held 12 months), then taxes the indexed gain at the higher of your marginal rate or 30 percent. A reference point only: what your tax would be if the whole holding period had fallen under the new rules.

Scenario C: Actual treatment. Based on your purchase and sale dates. Three possibilities:

• Pre-transition disposal (sale date before 1 July 2027): full old rules apply
• Post-transition acquisition and disposal (both dates after 1 July 2027): full new rules apply
• Held across the transition (purchase before 1 July 2027, sale after): the gain splits at a deemed sale just before 1 July 2027 into a deferred pre-2027 gain (50 percent discount where eligible, no minimum, taxed in the year of sale) and a post-2027 gain (indexation + 30 percent minimum)

The "Optional: 1 July 2027 valuation" field sets the value at the deemed sale. Enter the market value immediately before 1 July 2027; that is the default under the law and the only option for listed shares. For property and assets without a readily ascertainable market value, you can leave it blank to use the draft apportioning method.

Old rules vs new rules: the mechanics

Existing framework (until 30 June 2027)

For individuals, trusts, and partnerships disposing of a CGT asset held longer than 12 months, the gain is reduced by 50 percent before being added to assessable income. The remaining gain is taxed at the holder's marginal tax rate. Capital losses can offset capital gains but not ordinary income.

Worked example: AUD 30,000 cost base, AUD 100,000 sale, AUD 70,000 gain, held 4 years, 37 percent marginal rate. Discounted gain = AUD 35,000. Tax = AUD 12,950. Effective rate on raw gain = 18.5 percent.

New framework (from 1 July 2027)

The 50 percent discount is replaced by two mechanisms operating together:

1. Cost base indexation. If you owned the asset for 12 months, the cost base is multiplied by the CPI index for the quarter you sell divided by the index for the quarter the cost was incurred. If prices rose 3 percent a year over 16 quarters, the AUD 30,000 cost base becomes about AUD 30,000 × (1.03)^4 = AUD 33,765. Only the real (above-inflation) gain is taxed. For assets already held at 1 July 2027, indexation only counts from the September 2027 quarter.

2. 30 percent minimum tax. A top-up makes sure tax on post-2027 gains is at least 30 percent (before offsets, excluding Medicare). For someone with a 37 percent marginal rate, the minimum never binds. For someone in the lowest bracket (15 percent in 2026-27), it does. Anyone who received a payment on the closed income support list in section 119-15 that year is exempt.

Worked example continued, as if the whole four years fell under the new rules: AUD 30,000 cost base indexed to AUD 33,765, AUD 100,000 sale, indexed gain = AUD 66,235. Tax at 37 percent = AUD 24,507. Effective rate on raw gain = 35 percent (almost double the existing framework's 18.5 percent for the same disposal). In practice nobody who already holds the asset gets this result, because the gain to 30 June 2027 keeps the discount.

Why the change favours short holds with high inflation

The indexation benefit increases with holding period when inflation is high. For a 20-year hold with 3 percent CPI, the cost base nearly doubles. For a 2-year hold at the same CPI, it grows only 6 percent. The 30 percent minimum is more binding for low-marginal-rate holders. The 2026 budget framework therefore disadvantages long-held high-bracket investors (the typical SatoshiMacro reader profile) and is more neutral for short-held low-bracket investors.

How the 1 July 2027 transition works

If you hold an asset at 30 June 2027, the law (Subdivision 112-E) treats you as selling it just before 1 July 2027 and buying it back on 1 July 2027. That deemed sale does not create a tax bill in 2026-27. The gain to that point is deferred to the year you actually sell, keeps the 50 percent discount where eligible, and is not subject to the 30 percent minimum. Growth after 1 July 2027 is taxed under indexation plus the minimum.

Method A: market value (the default)

• Deferred pre-2027 gain = value_at_transition - cost_base
• Post-2027 cost base = value_at_transition, indexed from the September 2027 quarter if you owned the asset for 12 months in total
• Post-2027 gain = sale_price - indexed_post_cost_base
• Deferred gain tax = deferred_gain × 0.5 × marginal_rate (discount where eligible), taxed in the year of sale, no minimum
• Post-2027 tax = post_gain × the higher of marginal_rate or 0.30 (unless exempt)
• Total tax = deferred_gain_tax + post_tax

Market value immediately before 1 July 2027 is the default for every asset and the only option for listed shares. Liquid crypto very likely sits in the same bucket.

Method B: the apportioning method (draft)

Instead of market value, you can use an apportioning method set by ministerial instrument, chosen when you lodge for the year of sale. The draft instrument released on 4 August 2026 compounds daily growth from the first element of the cost base and only covers real property and assets without a readily ascertainable market value. Listed shares are excluded. The calculator models it as constant compound daily growth from cost base to sale price:

• value_at_transition = cost_base × (sale_price / cost_base)^(days_held_before_1_July_2027 / total_days_held)
• Then the same split applies as in Method A

The instrument is not final, so treat Method B results as an estimate. The calculator only offers it when the asset type is property or no readily ascertainable market value and the valuation field is blank.

Which method to use?

For listed shares there is no choice: market value. For property you can compare the two, and a formal valuation is optional because the apportioning method is available. For unlisted shares or private business interests, the apportioning method saves the cost of a valuation. The ATO has not yet ruled on transitional valuation.

Worked examples (shares, crypto, property)

Example 1: ASX share, transitional treatment

Bought 1,000 CBA shares in January 2020 at AUD 60 each (cost base AUD 60,000). Sold March 2028 at AUD 140 each (proceeds AUD 140,000). Market value just before 1 July 2027 was AUD 120 a share. Marginal rate 37 percent. CPI 3 percent.

• Deferred pre-2027 gain: 1,000 × (120 - 60) = AUD 60,000 × 0.5 discount = AUD 30,000 assessable × 37% = AUD 11,100 tax, taxed in 2027-28 when the shares are sold
• Post-2027 gain: cost base AUD 120,000 indexed two quarters (September 2027 to March 2028 quarters) at 3% annual CPI = AUD 121,787. Sale AUD 140,000. Indexed gain = AUD 18,213 × 37% = AUD 6,739 tax
• Total actual tax = AUD 17,839
• Compare to old rules applied to the whole gain: AUD 14,800
• Difference: AUD 3,039 more, or about 21 percent uplift

Example 2: Bitcoin, transitional treatment

Bought 1 BTC in January 2024 at AUD 30,000. Sold March 2028 at AUD 100,000. Market value just before 1 July 2027 was AUD 75,000. Marginal rate 37 percent. CPI 3 percent. These are the calculator's default inputs.

• Deferred pre-2027 gain: AUD 75,000 - AUD 30,000 = AUD 45,000 × 0.5 discount = AUD 22,500 assessable × 37% = AUD 8,325 tax, taxed in 2027-28
• Post-2027 gain: cost base AUD 75,000 indexed two quarters at 3% annual CPI = AUD 76,117. Sale AUD 100,000. Indexed gain = AUD 23,883 × 37% = AUD 8,837 tax
• Total actual tax = AUD 17,162
• Compare to old rules applied to the whole gain: AUD 12,950
• Difference: AUD 4,212 more, or about 33 percent uplift

Example 3: Investment property, transitional treatment

Bought investment property in March 2018 for AUD 600,000 (including stamp duty + legal fees). Sold in July 2029 for AUD 1,200,000. Market value just before 1 July 2027 was AUD 1,000,000. Marginal rate 45 percent. CPI 3 percent.

• Deferred pre-2027 gain: AUD 1,000,000 - AUD 600,000 = AUD 400,000 × 0.5 discount = AUD 200,000 assessable × 45% = AUD 90,000 tax
• Post-2027 gain: cost base AUD 1,000,000 indexed eight quarters (September 2027 to September 2029 quarters) at 3% annual CPI = AUD 1,060,900. Sale AUD 1,200,000. Indexed gain = AUD 139,100 × 45% = AUD 62,595 tax
• Total actual tax = AUD 152,595
• Compare to old rules applied to the whole gain: AUD 135,000
• Difference: AUD 17,595 more, or about 13 percent uplift

A formal valuation is optional here. Leave the valuation blank and the calculator applies the draft apportioning method instead: it puts the 1 July 2027 value at about AUD 1,059,279 and total tax at about AUD 137,633. Which method comes out ahead depends on how the property actually moved either side of the cutover, and the instrument is still in draft.

Example 4: Sub-12-month hold (no discount under either framework)

Bought ASX stock for AUD 20,000 in February 2027. Sold August 2027 for AUD 28,000. Held 6 months. Marginal rate 30 percent.

Under old rules (counterfactual if sold pre-1 July 2027): no 50% discount because held less than 12 months. Tax = AUD 8,000 × 30% = AUD 2,400.

Under actual treatment (held across the cutover, but under 12 months, so no discount and no indexation):

• The apportioning method is not available for listed stock, so the market value just before 1 July 2027 is used: assume AUD 25,000
• Deferred pre-2027 gain: AUD 5,000 × 30% (no discount) = AUD 1,500
• Post-2027 gain: no indexation because the shares were held under 12 months. Sale AUD 28,000 minus AUD 25,000 = AUD 3,000 × 30% = AUD 900. The 30 percent minimum applies to this portion regardless of holding period
• Total actual = AUD 2,400

Neutral at a 30 percent marginal rate, because the discount never applied. At a lower marginal rate the minimum lifts the post-2027 AUD 3,000 to 30 percent, so a short hold across the cutover can cost more than it did under the old rules.

Example 5: Capital loss

Bought ETF units for AUD 50,000. Sold for AUD 35,000. AUD 15,000 capital loss.

Under both old and new rules: no CGT payable. The AUD 15,000 capital loss carries forward indefinitely or offsets other capital gains in the same year. Capital losses still only offset capital gains, never ordinary income. What the reform changed is the order: under section 102-5, losses now reduce deferred pre-2027 gains first, then post-2027 gains, all before the discount. A dollar of loss used against a discounted deferred gain saves tax on 50 cents of gain; the same dollar used against a post-2027 gain would save tax on the full dollar. The calculator applies this ordering within a single asset (a fall after 1 July 2027 reduces the deferred gain first) but does not model losses from other assets.

What is NOT changing under the 2026 budget

• Main residence exemption. Your principal place of residence remains CGT-free. No change to the six-year absence rule, the partial-use rules, or the deceased-estate rules.
• Small business CGT concessions. The four existing concessions under Division 152 remain in place: 15-year exemption, 50 percent active asset reduction, retirement exemption, and rollover relief. The Senate amendments lifted the turnover threshold for the 50 percent active asset reduction to AUD 10 million; the other concessions keep the AUD 2 million turnover test.
• Complying superannuation funds. SMSFs and APRA-regulated super funds are outside the reform. The one-third discount is preserved, confirmed in the explanatory memorandum.
• Personal use asset exemption. Personal use assets costing AUD 10,000 or less remain exempt under section 118-10. Crypto rarely qualifies, because the test is its main use at the time of disposal. Collectables are a separate category with a AUD 500 threshold.
• Investor vs trader classification. TR 97/11 indicia continue to determine whether activity is business-like trading (ordinary income) or investment (CGT). No change.
• TR 2005/15 treatment of CFDs. Contracts for difference remain on revenue account regardless of holding period. Retail forex / CFD profits are unaffected by the CGT framework.
• Capital losses stay quarantined. Capital losses still only offset capital gains, not ordinary income. The order in which they apply did change (see Example 5).

What is still being finalised

The core law passed on 26 June 2026. These pieces are still open and may refine the calculator's logic:

• Apportioning method instrument. Released in draft on 4 August 2026. The final version may change the formula or which assets can use it.
• New residential dwelling instrument. Defines which dwellings get the choice between the 50 percent discount and indexation. Still in draft, including any acquisition-date condition.
• Tranche 2. Exposure drafts released on 4 August 2026 cover apportioned indexation for people whose residency changes, attribution managed investment trusts (AMITs) and a minimum tax for trusts. Not yet law.
• ATO guidance. The ATO has not yet ruled on transitional valuation.

There is no crypto-specific rule to wait for: each crypto-to-crypto swap after 1 July 2027 is a CGT event like any other, and it brings the deferred pre-2027 gain on the swapped coin to account. This calculator will be updated as the instruments are finalised and ATO guidance is published. Subscribe to the SatoshiMacro publication at govindsatoshi.substack.com for updates.

Related pillars and tools

For asset-class-specific deep dives covering deductions, classification, worked examples beyond what this calculator shows, and EOFY planning:

• 2026 Budget CGT Changes: cross-vertical pillar - full coverage of the law, transitional arrangements, and what is not changing
• Forex Tax Australia - retail forex and CFD trading: ordinary income vs CGT, deductions, classification under TR 97/11 and TR 2005/15
• Crypto Tax Australia - CGT events, the 50 percent discount, personal use exemption, DeFi, NFTs, SMSF, ATO data-matching
• Prop Firm Tax Australia - funded-trader payouts as ordinary income (CGT changes don't directly affect)

Existing calculators on related topics:

• Crypto CGT Calculator - single-disposal crypto CGT under existing rules (no 2026 budget framework)
• SMSF Crypto CGT Calculator - SMSF holders, one-third discount, 15 percent rate
• Tax-Loss Harvesting Calculator - EOFY loss-realisation strategy modelling
• All calculators - full toolkit

Frequently asked questions

About the author

Govind Satoshi

Former Institutional Trader. Founder, SatoshiMacro.

Traded allocated institutional capital at a Sydney proprietary trading firm.