Prepared 12 May 2026
CHALMERS, ALBANESE & GALLAGHER
Tax Consultants · Suburban Practice · Est. 2026
Capital Gains Tax - Damage Worksheet
Form 1A · Pre/Post Budget Comparison · Revision 12 May 2026
Calculator only. Not financial advice. Not affiliated with any government agency or accounting firm. Chalmers, Albanese & Gallagher is a fictional practice.

What’s the
CGT damage?

A · Asset details

1. Asset type

2. Purchase price

$

3. Stamp duty + legal

$

4. Acquisition date

dd / mm / yyyy

5. Hold for

hold period12 years
151015202530

6. Expected annual growth

per annum, compounding
%

7. Inflation / CPI assumption

see note 4
%

8. Your other taxable income *3

salary, rent, etc.
$

9. Selling costs (agent + legal)

$
*3 - The gain is stacked on top of your other income; the marginal rate is derived from where the stacked income lands in the brackets. See notes overleaf.
B · Calculation summary
The damage:
$91,678
(in today’s $: $68,168)
Chalmers, Albanese & Gallagher - Tax Consultants. Calculator only. Not financial advice. Not affiliated with any government agency or accounting firm.
Scenario A
Pre-Budget rules
50% CGT discount
Scenario B
Post-Budget rules
Indexed cost base · 30% floor
Sale price$1,914,363
Sale price$1,914,363
Cost base$895,000
Cost base$1,203,675
Taxable gain$498,681
Taxable gain$688,687
Tax Payable$239,814
Tax Payable$331,492
After-tax proceeds (nominal)$1,652,549
After-tax proceeds (nominal)$1,560,871
After-tax proceeds (today's $)$1,228,763
After-tax proceeds (today's $)$1,160,595
Fig. 1

After-tax proceeds: pre vs post Budget rules

Pre-Budget (50% discount)Post-Budget (indexed + 30% floor)
$500,000$1,000,000$1,500,000$2,000,000$2,500,000$3,000,0001y5y10y15y20y25y30yafter-tax proceeds (today’s $)holding period (years)

Both lines are after-tax proceeds in today’s dollars (deflated by CPI). Solid = old 50%-discount rules; dashed = post-Budget rules (indexed cost base, 30% floor). The shaded gap is the damage. Bends in either line are tax-bracket transitions.

Note 1 - Brackets

2025-26 ATO resident individual rates plus a flat 2% Medicare levy. Low-income thresholds and offsets are not modelled here.

$0 - $18,2000%
$18,201 - $45,00016%
$45,001 - $135,00030%
$135,001 - $190,00037%
$190,001+45%
Note 2 - Post-Budget formula

The 50% discount is replaced by indexation of the cost base. A 30% minimum effective rate applies to the net gain.

Indexed cost base
B′  =  B · (1 + π)t
Net gain
G  =  max{ 0,  S − B′ − c }
Tax payable
T  =  max{ τ(G),  0.30 · G }
B = cost base (purchase + buying costs); π = CPI rate; t = years held; S = sale price; c = selling costs; τ (G) = the progressive income tax on G when stacked on other income (see Note 3).
Note 3 - Stacking

The gain is stacked on top of your other taxable income. The marginal rate is derived from where the stacked income lands in the brackets. A higher salary pushes the gain into a higher bracket.

Note 4 - Reform start and indexation

The new regime applies to gains arising on or after 1 July 2027, regardless of when the asset was acquired. Sales before that date keep the existing 50% discount. Indexation uses your CPI assumption (section 7) as a single annual compound rate. The 7:30pm AEST, 12 May 2026 cutoff that you may have read about applies to negative gearing on established residential property, not CGT.