Australia’s CGT rules have changed. The Treasury Laws Amendment (Tax Reform No. 1) Bill 2026 received Royal Assent in June 2026: from 1 July 2027, the 50% CGT discount for individuals and trusts is replaced by CPI-indexed cost bases plus a 30% minimum tax on gains.

There’s good news: it’s grandfathered. Gains accrued to 30 June 2027 keep the 50% discount; only gains from 1 July 2027 onward fall under the new regime.

The catch: if you bought before 1 July 2027 and sell after, your gain must be split in two, based on proving what your property was worth on 30 June 2027, via an independent valuation, or an unfinalized default formula if you have none. Once that date passes, genuine contemporaneous evidence is gone. The window to lock in your cost base closes on 30 June 2027.

The cost of doing nothing, a worked example

An investor bought a property for $1,000,000 ten years ago. It’s worth $2,000,000 today. On current trajectory, a valuation at 30 June 2027 might show $2,150,000. They sell in 2031 for $3,000,000.

With a valuation: – Pre-2027 gain: $1,150,000 → 50% discount applies → $575,000 taxed at marginal rates. – Post-2027 gain (indexed): roughly $627,000 exposed to the 30% minimum tax.

Without a valuation (illustrative worst case): – No evidence of accrued pre-2027 gain means the entire $2,000,000 nominal gain risks falling under the new regime, with only CPI indexation back to 2016. – Real gain of roughly $1,552,000, the whole gain taxed at the 30% minimum, with no 50% discount at all.

That’s around $925,000 more exposed to the less concessional treatment, purely from failing to document one number at one point in time.

(Simplified for illustration; excludes costs, fees and individual tax rates. The default formula isn’t yet settled, outcomes depend on your circumstances.)

What to do

Get an independent valuation dated at 30 June 2027 for any pre-2027 CGT asset you’re not selling before then. Keep the report and supporting evidence on file for the ATO. Talk to your accountant now, before the window closes. The 50% discount has shaped property investment for two decades. What you do before 30 June 2027 will determine how much of your past gain still benefits from it.