Budget 2026 changed CGT for property and shares. I built a free calculator showing old vs new rules side by side. Would love feedback on the maths.
Update: Calculator has been updated based on feedback from this thread. Tax is now stacked across the correct brackets using your existing salary, including 2% Medicare levy. You can also expand "See bracket breakdown" to see exactly how the gain is split across brackets. Thanks to everyone who pointed out the issues.
Updated screenshot here: https://www.reddit.com/user/RipperWealthAU/comments/1tcn5dy/property_cgt_calculator_updated_with/
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After the Budget I built a free calculator comparing the legacy 50% CGT discount against the new inflation-indexed cost base rules.
Example: $600k investment property bought in 2018, sold for $1.2M today (with $25k in improvements and $25k selling costs). Annual income: $100k.
Old rules: $550k gain, 50% discount → $275k taxable. Tax is stacked on top of your $100k salary across brackets (30%, 37%, 45%) plus 2% Medicare levy = $119,600 tax. Net profit $430,400.
New rules (for any property bought after Budget night): the 50% discount is gone. Instead your cost base is inflation-adjusted to $812,948, so the real gain is $387,052. Tax across brackets + Medicare = $172,265. Net profit $377,736.
That is $52,665 more tax on the same sale.
There is a dedicated property version (with improvements, selling costs, and grandfathering toggle) and a general version for shares, crypto, and gold.
I also wrote a plain-English breakdown of all three Budget changes (CGT, negative gearing, trust distributions) if you want the context.
Looking for feedback specifically on:
Is the pre-budget grandfathering logic correct?
The new-build opt-in: should the toggle default to old rules or new?
CPI series: I am using ABS 6401.0 quarterly. Anyone using a different reference?
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