How to calculate your break-even for a 2027 CGT valuation

The setup: what changes at 30 June 2027

From 1 July 2027, the 50% CGT discount is replaced by cost-base indexation and a 30% minimum tax for covered gains. For property held across the cutover, the default is a reset to market value at 30 June 2027 — the value you can show your property to have on that date becomes the baseline for tax on everything after it. That reset was enacted in June 2026.

A separate item: An alternative apportionment method may be determined by the Minister under s 112-185 — no apportionment instrument is currently registered. Treasury's exposure draft of 3 August 2026 uses compound growth (nine-step). It is draft — not law. The Treasury Laws Amendment (Tax Reform No. 3) Bill 2026 was introduced on 14 October 2026 and is not yet law. If it becomes law, this guide and our reports will say so plainly.

The value-defended framing (why "break-even" is the right question)

A valuation is worth paying for if, and only if, it defends more baseline value than you could evidence any other way — and by enough to cover its own fee. So the useful question is not "how much will I be taxed?" but "how much extra baseline does this valuation need to defend to pay for itself?"

A $250–$400 desktop valuation pays for itself if it defends roughly $1,351–$2,162 more of your 30 June 2027 baseline than you could evidence without it (about the fee divided by a 37% marginal rate × 0.5). Inspected valuations are about $500–$760. The question is whether your position makes that likely.

That's the whole calculator: your cost base, then a comparison between what you already know and what a valuation might add.

Step 1 — build the indicative cost base

Your cost base is roughly what the property has cost you to acquire. Any comparison against a valuation happens against this figure, not just the price you paid. For most acquisitions it's:

• Purchase price
• Transfer duty (stamp duty) at the rate table current for your contract date, calculated from published state and territory schedules
• Conveyancing, inspections and registration (standard assumption or your figure)
• Buyer's agent fee, if you used one
• Any capital improvements since purchase you've told us about

Borrowing costs (LMI, loan fees) are not cost base — they're generally deductible over five years. If you've claimed capital works deductions on improvements (Division 43), those amounts may not add back to cost base — your tax agent decides.

Step 2 — a worked example (invented figures)

All figures here are invented and labelled — this is a walk-through, not a template for your property. Use the calculator for your own numbers.

Step 3 — sensitivity, and when to stop guessing

The example above is comfortable at every haircut — the answer doesn't change. Many properties aren't. When the finding flips between the as-entered estimate and a 10-20% haircut, your position is unresolved on free-tier data. That's exactly the situation an independent valuation (or a paid report with the AVM + comparable-sales spread) is designed to settle.

The renovation path is the mirror image: if you've done significant works since purchase, portal estimates and automated models understate your position because they can't see what you've built. In that case the break-even question flips — the valuation pays for itself if the works add more than ~$3,000 of defensible value at the cutover, which most real renovations clear on the first receipt.