The Capital Gains Sting Nobody Warned You About

The federal budget promises to tackle intergenerational wealth inequality. But if you’re a working-age millennial with investments, a family, and kids in childcare — a single good year on paper could quietly cost you thousands.

There’s been a lot of noise lately about the federal budget and what it means for younger Australians trying to build wealth. The headlines talk about housing, superannuation, and making things fairer for the next generation.

But buried beneath all of that is a quieter problem, one that doesn’t make it into press releases.

If you’re a millennial who has managed to accumulate some investments — shares, an investment property, a business — realising a larger-than-expected capital gain in any given financial year can trigger a cascade of unexpected tax and benefit consequences that go well beyond your marginal income tax rate.

Here’s what you need to know.

First: What Is “Assessable” Capital Gain?

When you sell an asset for more than you paid for it, you make a capital gain. Currently, if you’ve held the asset for more than 12 months, you’re eligible for the 50% CGT discount — meaning only half of the gain is added to your taxable income.

That remaining portion — the taxable half — is your assessable capital gain, and it’s treated just like ordinary income for most purposes. The budget changes summarised here mean that selling an asset after 1 July 2027 may mean the assessable amount rises going forward under a CPI-linked model.

This matters because your assessable capital gain doesn’t just affect your income tax. It flows into a range of other calculations that can affect your family’s finances in ways that are far from obvious.

Hit 1: Division 293 Tax — Your Super Contribution Just Got More Expensive

Division 293 (Div 293) is an additional 15% tax on concessional super contributions for high-income earners. It kicks in when your income — as defined by the ATO for this purpose — exceeds $250,000.

That “income” definition includes your assessable capital gains.

So imagine you earn $180,000 in salary and you’ve made $25,000 in concessional super contributions this financial year (say, through salary sacrifice plus employer contributions). In a normal year, you’re well below the $250,000 threshold.

Now imagine you sell an investment and realise an $80,000 assessable capital gain.

Suddenly your combined income and super contributions for Div 293 purposes is $281,600 — $31,600 above the threshold. The ATO will levy an additional 15% tax on the lower of your concessional contributions or the amount above $250,000. In this case, that’s an extra $3,750 on top of what you expected to pay — though this amount can be paid from your super.

Additionally, Div 293 is not currently indexed, making it a form of silent bracket creep for higher earners.

Hit 2: Family Tax Benefit — A Clawback You Didn’t Budget For

Family Tax Benefit (FTB) is income-tested. Both Part A and Part B use your family’s adjusted taxable income (ATI) to calculate entitlements — and ATI includes assessable capital gains.

If you’ve been receiving FTB payments throughout the year based on an estimated income, and then you realise a capital gain that pushes your ATI above those thresholds, the result at tax time is a debt to Centrelink.

Here’s an example: a family with two children estimates their income at $110,000 and receives FTB Part A accordingly. They then sell shares mid-year, realising a $60,000 assessable capital gain — bringing their ATI to $170,000. When reconciliation happens, they may find they’ve received thousands of dollars in FTB they weren’t entitled to, and they’ll need to pay it back.

Many families don’t realise this until well after they’ve spent those payments.

Hit 3: The Child Care Subsidy — Where the Cliff Gets Steep

The Child Care Subsidy (CCS) is calculated using your combined family income, and the rate you receive can change significantly across income bands.

At the time of writing, families earning under $85,279 can receive up to 90% subsidy. That rate then tapers as income rises, eventually reaching 0% for families over $535,279.

Because assessable capital gains flow into the income figure used to calculate CCS, a one-off gain in a single year can move a family into a meaningfully lower subsidy band — even if their regular income hasn’t changed at all.

For a family with one child in full-time childcare at, say, $150 per day, the difference between an 85% and a 50% subsidy rate represents roughly $16,000 per year in out-of-pocket costs. Even a partial-year impact can be painful.

Like FTB, CCS is reconciled annually. If your CCS payments were based on an estimated income that turned out to be too low because of a capital gain, you’ll receive a reduced subsidy going forward — or have to repay an overpayment.

Get Ahead of It

If you’re expecting a capital gain this financial year — from an investment property, a share sale, a trust distribution, or any other source — it’s worth sitting down with a financial adviser before the end of June, not after.

The difference between a well-timed strategy and an unexpected tax debt can be significant. Understanding how your assessable income interacts with your super, your family payments, and your childcare subsidy is exactly the kind of planning that turns a good financial outcome into a great one.

Important disclaimer: This article is general in nature and does not constitute financial or tax advice. Please consult your adviser for advice specific to your circumstances here.