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 (full 2026 budget framework). Applies cost base indexation against CPI over the entire holding period, then taxes the indexed gain at max(marginal_rate, 0.30). Used as the post-transition reference point (what your tax would be if the asset had been acquired AFTER 1 July 2027).

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
• Transitional apportionment (purchase before 1 July 2027, sale after): the gain is split into pre-transition (50 percent discount) and post-transition (indexation + 30 percent minimum) portions

The "Optional: 1 July 2027 valuation" field controls how the pre-transition portion is calculated for transitional cases. Leave blank to use the apportionment formula (straight-line by holding-period days). Fill in the actual market value at 1 July 2027 if you have a quoted price (for listed securities and liquid crypto) or a formal valuation (for property).

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. The cost base is uplifted by CPI over the holding period. For 4 years at 3 percent annual CPI, the AUD 30,000 cost base becomes AUD 30,000 × (1.03)^4 = AUD 33,765. Only the real (above-inflation) gain is taxed.

2. 30 percent minimum tax rate. The indexed gain is taxed at max(marginal_rate, 0.30). For someone with a 37 percent marginal rate, the 30 percent floor never binds. For someone in the 19 percent bracket, the 30 percent floor applies. Income support recipients (Age Pension, JobSeeker, DSP, Carer Payment) are exempt from the floor.

Worked example continued: 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).

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 transitional apportionment works

For assets purchased before 1 July 2027 and sold after, the gain is split into two periods. Two valuation methods are available:

Method A: User-supplied 1 July 2027 valuation

If you have a market price or formal valuation at 1 July 2027, use it as the pivot:

• Pre-transition gain = valuation_at_transition - cost_base
• Post-transition starting cost base = valuation_at_transition
• Post-transition indexed cost base = valuation_at_transition × (1 + CPI)^post_period_years
• Post-transition gain = sale_price - indexed_post_cost_base
• Pre-transition tax = pre_gain × 0.5 × marginal_rate (if held over 12 months at disposal)
• Post-transition tax = post_gain × max(marginal_rate, 0.30)
• Total tax = pre_tax + post_tax

This method is preferred for listed securities (closing price on 30 June 2027), liquid cryptocurrencies (exchange-quoted price), and assets with a formal valuation.

Method B: Specified apportionment formula

For assets without a quoted price or formal valuation, the apportionment formula uses straight-line allocation by holding-period days:

• preFraction = days_from_purchase_to_30_June_2027 / total_holding_days
• valuation_at_transition = cost_base + (total_gain × preFraction)
• Then the same pre / post split applies as in Method A

This is administratively simpler and is the default when the "1 July 2027 valuation" field is blank.

Which method to use?

For listed shares and major cryptocurrencies, Method A is more accurate because actual market prices at 30 June 2027 will be observable. For illiquid assets (unlisted shares, business goodwill, niche property) Method B is the standard approach. The taxpayer can elect either method asset-by-asset. ATO guidance during the legislative process will clarify edge cases (mid-quarter valuations, suspended trading, etc.).

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). CBA closing price at 30 June 2027 was AUD 120. Marginal rate 37 percent. CPI 3 percent.

• Pre-transition gain: 1,000 × (120 - 60) = AUD 60,000 × 0.5 discount = AUD 30,000 assessable × 37% = AUD 11,100 tax
• Post-transition gain: cost base AUD 120,000 indexed 9 months at 3% CPI = AUD 122,700. Sale AUD 140,000. Indexed gain = AUD 17,300 × 37% = AUD 6,401 tax
• Total actual tax = AUD 17,501
• Compare to old rules (full disposal pre-1 July 2027): AUD 14,800
• Difference: AUD 2,701 more, or about 18 percent uplift

Example 2: Bitcoin, transitional treatment

Bought 1 BTC in January 2024 at AUD 30,000. Sold March 2028 at AUD 100,000. BTC closing price at 30 June 2027 was AUD 75,000. Marginal rate 37 percent. CPI 3 percent.

• Pre-transition gain: AUD 75,000 - AUD 30,000 = AUD 45,000 × 0.5 discount = AUD 22,500 assessable × 37% = AUD 8,325 tax
• Post-transition gain: cost base AUD 75,000 indexed 9 months at 3% CPI = AUD 76,688. Sale AUD 100,000. Indexed gain = AUD 23,312 × 37% = AUD 8,625 tax
• Total actual tax = AUD 16,950
• Compare to old rules (full disposal pre-1 July 2027): AUD 12,950
• Difference: AUD 4,000 more, or about 31 percent uplift

Example 3: Investment property, transitional treatment

Bought investment property in 2018 for AUD 600,000 (including stamp duty + legal fees). Sold in 2029 for AUD 1,200,000. Formal valuation at 30 June 2027 was AUD 1,000,000. Marginal rate 45 percent. CPI 3 percent.

• Pre-transition gain: AUD 1,000,000 - AUD 600,000 = AUD 400,000 × 0.5 discount = AUD 200,000 assessable × 45% = AUD 90,000 tax
• Post-transition gain: cost base AUD 1,000,000 indexed 2 years at 3% 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 (full disposal pre-1 July 2027): AUD 135,000
• Difference: AUD 17,595 more, or about 13 percent uplift

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 (transitional, but sub-12-month so no discount applies on the pre-portion either):

• Apportionment formula puts valuation at 1 July 2027 at AUD 24,667 (5/6 months pre, 1/6 month post)
• Pre-transition gain: AUD 4,667 × 30% (no discount) = AUD 1,400
• Post-transition gain: cost base AUD 24,667 indexed 1 month at 3% CPI = AUD 24,728. Sale AUD 28,000. Indexed gain = AUD 3,272 × max(30%, 30%) = AUD 982
• Total actual = AUD 2,382

The 2026 budget change is essentially neutral for sub-12-month holds because the discount never applied. Tiny indexation benefit on the post-transition portion.

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. The 2026 budget changes do not affect loss treatment - capital losses still only offset capital gains, never ordinary income.

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.
• Complying superannuation funds. SMSFs and APRA-regulated super funds are not expected to lose CGT discount eligibility under the announced measures. The one-third discount applicable to complying super funds is preserved.
• Personal use asset exemption. Crypto, collectibles, and other personal use assets under AUD 10,000 in cost remain exempt under section 118-10.
• 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.
• CGT loss quarantining. Capital losses still only offset capital gains, not ordinary income.

Watch list as legislation moves

The 2026 budget measures are announced but not yet legislated. The enabling bill will move through Parliament in the second half of 2026 with effect from 1 July 2027. Items that may refine the calculator's logic:

• Final text of the apportionment formula. Treasury indicated a "specified formula" but the exact mechanics (caps, floors, anti-avoidance) will be set in the bill.
• Valuation methodology for illiquid assets. Specific guidance for unlisted shares, business interests, and thin-market real property.
• Treatment of crypto-to-crypto trades. Whether each crypto-to-crypto trade triggers immediate apportionment or whether a simplified treatment applies pending disposal.
• ATO Practice Statements and draft rulings. Expected in Q1 2027 covering valuation, indexation, and the 30 percent minimum.
• Interaction with the TOFA regime. Whether financial-arrangement taxpayers electing TOFA methods are affected.

This calculator will be updated as legislation passes 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 announcement, 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.

Sydney-based. Principal of Digital Empire Capital, a proprietary digital asset investment vehicle operating since 2017. Formerly traded allocated institutional capital at a Sydney proprietary trading firm. Active seed investor in early-stage protocols.