Assumptions, data and tax treatment

Every figure the Australian Portfolio Lab shows is computed in your browser from the data and rules on this page. Every default below can be changed in the tool. Nothing you enter leaves your computer.

What the tool does

It replays a chosen portfolio mix through every historical window of Australian financial years — FY1971 onward for mixed portfolios, earlier for Australian-shares-only mixes — applying contributions, fees, account-level tax and inflation, and shows the full range of outcomes: worst, median and best. It is general information only: it does not consider your objectives, financial situation or needs, and past performance is not a reliable indicator of future performance.

Data sources

Historical asset-class returns: Andex Charts Pty Ltd, via the Vanguard Asset Class Tool (retrieved July 2026), cross-checked against Reserve Bank of Australia and Australian Bureau of Statistics published data. Bond yields and CPI: RBA/ABS published series. The financial-year figures used here reconcile with the numbers printed in the published Vanguard Index Chart.

The stress test offers three preset mixes. Its monthly figures are blended whole-portfolio returns (standard mix) and precomputed crisis-event facts (Australian-only and international-only mixes) derived from the sources above; the month-by-month returns for individual asset classes are Andex Charts' compilation and are not republished here.

The complete method and data ship with the page. The website's calculation engine is verified, before every update, to reproduce IYI's internal adviser tooling to the cent across tens of thousands of checks.

Asset classes and portfolio construction

• Growth assets: Australian shares and international shares (index exposure), split 45/55 by default; US shares and Australian listed property can be added under "More options".
• Defensive assets: Australian bonds by default, with a small cash floor (3% of the portfolio; 8% in pension accounts). The bonds/cash balance is adjustable.
• Portfolios rebalance implicitly each financial year (weights held constant). Capital gains tax is not modelled: portfolios are held to the horizon and rebalancing is assumed managed without net realisations. The Tax view on the main page explains why.

Fees

Fee	Default	Notes
Adviser fee	1.1% p.a. incl. GST (options 1.1–1.3%; or none)	15% tax credit inside super accumulation; no credit in pension; not tax-deductible outside super.
Platform (wrap) fee	0.275% p.a. incl. GST when an adviser is used	Same tax treatment as the adviser fee in super; deductible at your marginal rate outside super.
SMSF administration	Off by default; $4,000 p.a. when selected	Held in today's dollars (indexed with inflation); deductible to the fund in accumulation (15% credit), no credit in pension. Super accounts only.
Fund fees (MER)	Mean of the three biggest ASX ETF providers' flagship index funds, per asset class	No tax credit; subtracted from gross index returns. Editable.

MER basis (as at July 2026)

Asset class	Funds averaged	Mean used
Australian shares	VAS 0.07% · A200 0.04% · IOZ 0.05%	0.05%
International shares	VGS 0.18% · BGBL 0.08% · IWLD 0.09%	0.12%
US shares	VTS 0.03% · IVV 0.04%	0.04%
Australian listed property	VAP 0.23%	0.23%
Australian bonds	VAF 0.10% · IAF 0.10% · OZBD 0.19%	0.13%
Cash	AAA 0.18% · BILL 0.07%	0.13%

Where a provider has no comparable flagship fund in a class, the mean uses those available. Fund names appear here as the basis of a fee assumption, not as recommendations.

Tax treatment

• Super — accumulation: investment income taxed at 15% on the franking-grossed-up amount less franking credits; contributions treated as gross concessional and taxed 15% on entry; advice and wrap fees receive the 15% credit.
• Pension: zero tax on investment income; franking credits refunded in full; statutory minimum drawdowns by age are paid out and counted in the outcomes shown; no contributions.
• Outside super: your selected marginal rate applies to the grossed-up income less franking credits; the advice fee is not deductible; wrap and MER are.
• Franking: 77% of Australian-share income franked at a 30% company rate, from FY1988 (imputation began 1 July 1987). Where net income tax is positive it is reduced by a credit equal to 15% of the tax.
• Capital gains tax is not modelled (see above).

Timing conventions

• Contributions arrive mid-year and earn half the year's return.
• Contributions grow over time: 5% a year by default in super accumulation (wages and contribution caps rise), flat by default outside super. The rate is adjustable in the tool ("Contribution growth % p.a."; set 0 for a flat amount every year).
• Medians: with an even number of historical windows, the upper-middle window is reported — the same convention as IYI's desktop engine, so every view shows the same median.
• Fees and income tax are charged on the average of opening and pre-fee closing balances.
• Pension minimums are drawn on the opening balance at the age-based statutory rate, mid-year on average.
• "Today's dollars" deflates by actual CPI for each year of the window (a fixed rate or no inflation can be selected instead).

The stress test

"The cost of selling out" simulates an investor who sells everything in the month their portfolio is first down the chosen percentage from its peak (checked monthly from 1970 onward), then stays in cash for the rest of the window — fees and cash-income tax continue, and any contributions keep arriving into cash. The optional third bar sells at the lowest point of the same fall instead. It offers three preset mixes — the standard 45/55 growth mix, Australian shares only, and international shares only, each with bonds defensive; the custom splits under "More options" apply to the other views. The GFC drawdown figures quoted beside the chart (Australian shares −48%; international shares in AUD −38%; the standard 45/55 blend at 100% growth −39%; the default 70% growth portfolio −27%; peak to trough, Jul 2007 – Jun 2009) come from the same monthly data, shipped with the site in data/facts.json; an automated repository check fails if the figures on this page drift from that file.

About

Built by In Your Interest Financial Planning. In Your Interest Financial Planning Pty Ltd, ABN 28 094 300 464 is Authorised Rep. No 308161 of Fiduciary Duty Advisers Pty Ltd AFSL No 527434. Questions and corrections are welcome — contact us.