The Quick Guide to Australia's New Property CGT Rules
25 May 2026
10 minutes
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If you bought an investment property before the latest budget rules and plan to sell it in the future, the law is changing. Your tax calculation will soon split into two different eras. If you miss one vital step, getting a physical property valuation by 30 June 2027, the ATO default system will artificially inflate your taxable profit. This short guide shows you exactly how to protect your money.
Australia's property tax rules are entering a new chapter. For decades, the calculation was simple: take your total profit, cut it in half with the 50% discount, and pay tax on the rest. Under the new laws, that flat discount is ending for the modern era of your ownership.
Because most existing property owners held their asset through both the old laws and the new laws, the tax outcome is no longer one clean calculation. It splits into two chapters: Phase 1 (the old discount method) and Phase 2 (the new inflation-shield method). The point where the two chapters meet is your property value on 30 June 2027.
This guide walks through that split-era calculation in plain language, shows the dollar impact of getting it right (or wrong), and explains why a certified valuation and proper tracking matter more than ever.
For decades, calculating property tax was simple. You took your total profit, cut it in half with the 50% discount, and paid tax on the rest. Under the new laws, that flat discount is ending.
Because you owned your property during both the old laws and the new laws, you must calculate your tax in two split chapters: Phase 1 (the discount method) and Phase 2 (the new inflation-shield method). The dividing line between them is the market value of your property on 30 June 2027.
The number that bridges the two eras is not your purchase price and it is not your sale price. It is the certified market value on 30 June 2027. Get that number right and the rest of the calculation has a strong foundation. Get it wrong and every dollar above that value is taxed under the harsher modern rules.
To make the new rules concrete, we will walk through one realistic example throughout the guide. Here are the numbers we will be working with.
| Property Event / Milestone | Value / Amount |
|---|---|
| Original purchase price (bought in 2020) | $800,000 |
| Real market value on 30 June 2027 (valuation date) | $1,200,000 |
| Major renovation costs (spent in 2029) | $200,000 |
| Final selling price (sold in June 2032) | $1,800,000 |
The new rules break your gain into two separate parts. Phase 1 covers the growth from purchase up to 30 June 2027 and is taxed under the old 50% discount rule. Phase 2 covers the growth from 1 July 2027 to the sale date and is protected by an inflation shield instead of a flat discount.
| Timeline Step | Simple Explanation | Amount / Factor |
|---|---|---|
| Phase 1: The Old Rules, Growth up to 30 June 2027 | ||
| Step 1: Get 2027 market value | The property value baseline at rule transition. | $1,200,000 |
| Step 2: Deduct purchase price | Minus the original amount paid in 2020. | − $800,000 |
| Step 3: Apply 50% concession | Old rule cuts this era's $400,000 profit in half. | × 50% discount |
| Phase 1 taxable profit subtotal | The taxable profit from the first part of your ownership. | $200,000 |
| Phase 2: The New Rules, Growth from 1 July 2027 to 2032 Sale | ||
| Step 4: Factor in final sale price | The amount the buyer paid you in June 2032. | $1,800,000 |
| Step 5: Index the 2027 baseline | $1.2M value raised by 12% for inflation protection. | − $1,344,000 |
| Step 6: Index the renovations | $200k renovation cost raised by 6% for inflation protection. | − $212,000 |
| Phase 2 taxable profit subtotal | Sale price minus inflation-protected costs (Step 4 − 5 − 6). | $244,000 |
| Final combined taxable profit | Phase 1 subtotal ($200,000) + Phase 2 subtotal ($244,000). | $444,000 |
If you do not get a certified, physical property valuation on or near 30 June 2027, you are trapped. You cannot reliably guess the value years later. The ATO will step in and force you to use their straight-line apportionment formula. This formula flattens your growth and spreads it evenly across all days of ownership.
Because real estate grows in waves, this formula often flattens your early rapid gains. It mathematically lowers your 2027 baseline down to a default number (for example, $1,000,000 instead of the true $1,200,000). Because your post-2027 inflation shield is calculated as a percentage of your baseline, a lower starting number directly shrinks your tax protection. You instantly lose chunks of your tax-free inflation shield and push more profit into higher-taxed brackets.
In other words:
Missing the 30 June 2027 valuation is not a paperwork problem. It is a tax problem. The ATO's default formula consistently produces a worse outcome for owners whose property grew strongly in the years before 2027.
The table below puts the two scenarios side by side. Scenario A is what happens if you do nothing and the ATO applies its default apportionment formula. Scenario B is what happens when you secure a certified valuation in time.
| Milestone Step | Scenario A: ATO Formula (No Valuation) | Scenario B: Correct Baseline (With Valuation) | The Layman Reality |
|---|---|---|---|
| 1. Deemed 2027 value | $1,000,000 (artificially lowered) | $1,200,000 (certified true value) | The baseline where your inflation shield starts. |
| 2. Phase 1 taxable profit | $100,000 (after 50% discount) | $200,000 (after 50% discount) | Your early profit cut in half by old rules. |
| 3. Inflation shield (12%) | $120,000 (weaker tax-free shield) | $144,000 (stronger tax-free shield) | Your protection allowance against paper profits. |
| 4. Phase 2 taxable profit | $468,000 (heavy modern profit pool) | $244,000 (protected modern profit pool) | Your modern taxable profit under new rules. |
| 5. Total taxable profit | $568,000 | $444,000 | The final profit amount you report to the ATO. |
| 6. Final out-of-pocket tax | $266,960 | $208,680 | The real cheque you write to the tax office. |
The out-of-pocket cash savings:
Scenario A ($266,960) − Scenario B ($208,680) = $58,280 extra cash left in your pocket.
Many property owners try to track their portfolios using a home-made Excel file. Under these split-era tax laws, manual tracking is incredibly dangerous for three main reasons.
To eliminate tracking errors and securely lock in your $58,280 in savings, moving to an automated tech ally like The Property Accountant is essential.
These insights are based on initial budget papers and announcements. Final laws are subject to legislative adjustments. Property investors must consult a certified tax agent or financial professional before declaring any portfolio strategy.
Written by
Sid Kawar
Founder, The Property Accountant
