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Understanding super contributions in Australia

How the 15 per cent super tax break works

Concessional (before-tax) super contributions, the ones you salary-sacrifice or claim as a personal tax deduction, are taxed at a flat 15 per cent as they enter your fund, instead of the marginal rate of up to 47 per cent (including Medicare levy) you would otherwise pay on that income. The benefit is simply the gap between your marginal rate and 15 per cent. On the 30 per cent bracket that is 15 cents saved in every dollar redirected; on the 37 per cent bracket it is 22 cents; near the top it is 32 cents. This calculator approximates the resulting annual benefit by applying a representative gap, but the principle holds across brackets: the higher your income, the larger the gap and the bigger the saving on every dollar you put in.

The cap, and why it includes your employer's contributions

Every concessional dollar shares one ceiling. The cap is $30,000 for the 2025-26 financial year and rises to $32,500 from 1 July 2026, and it is indexed in steps over time. The detail that trips people up is that this ceiling includes your employer's compulsory Super Guarantee, currently 12 per cent of your salary. A worker on $95,000 therefore already has roughly $11,000-$11,500 of the cap consumed by employer contributions before adding a cent of their own, leaving genuine salary-sacrifice headroom of around $18,000-$19,000. Always start by working out the room you actually have, not the headline cap, or you risk sacrificing straight past the limit.

Carry-forward: using more than one year at once

The rules reward people with uneven incomes. If your total super balance was under $500,000 at the previous 30 June, you can carry forward unused concessional cap from the past five financial years and use it all in a single bigger year. That is powerful after a windfall, an inheritance, a redundancy or selling an asset with a large capital gain, because you can offset the spike by funnelling well over the annual cap into super at 15 per cent rather than your marginal rate. The unused amounts expire on a rolling five-year basis, so they are a use-it-or-lose-it resource; check your available carry-forward in ATO online services before you contribute, as the figure is calculated for you there.

Division 293 and the low-income offsets

Two adjustments sit at opposite ends of the income scale. Very high earners face Division 293, which applies an extra 15 per cent contributions tax once combined income and concessional contributions pass $250,000, lifting the effective rate on the affected contributions to 30 per cent. That narrows the benefit but rarely erases it, since 30 per cent still beats a 47 per cent marginal rate. At the other end, lower-income earners may do better outside concessional contributions altogether: the government co-contribution, the low-income super tax offset and spouse contribution offsets can deliver bonuses that exceed a marginal-rate saving. Whoever you are, the right strategy depends on your bracket, not a blanket rule.

The catch: your money is locked away

The trade-off for the tax break is access. Going over the cap is the main own goal, excess concessional contributions are added back to your assessable income and taxed at your marginal rate, with an offset for the 15 per cent already paid, so the headline advantage disappears and you may face an interest charge too. The good news is that the ATO no longer leaves you stranded with excess money locked away: you can usually elect to have up to 85 per cent of an excess concessional contribution released from your fund to help pay the resulting tax bill, but it is far cleaner to stay inside the cap in the first place. And every dollar you contribute is preserved: it generally cannot be touched until you reach your preservation age (between 55 and 60 depending on your birth year) and meet a condition of release such as retiring. Salary sacrifice is a long-term wealth strategy, not an emergency fund, so never contribute money you might need before retirement. This is general information only, confirm your cap, carry-forward and Division 293 position with the ATO or a licensed financial adviser before contributing.

A worked example on a $95,000 salary

Run the numbers end to end and the trade-off becomes obvious. On $95,000 you sit in the 30 per cent marginal bracket, which with the 2 per cent Medicare levy makes an effective 32 per cent. Your employer's 12 per cent Super Guarantee contributes about $11,400, leaving roughly $18,600 of concessional headroom under the $30,000 cap. Sacrifice $10,000 of that and the contribution is taxed at 15 per cent inside the fund, costing $1,500, where the same $10,000 taken as salary would have cost about $3,200 in tax. The saving is around $1,700 a year. Your take-home pay falls by roughly $6,800, not $10,000, because you were never keeping the tax portion anyway, which is the point most people miss when they look at the payslip and panic. Repeat that for 20 years at a 6 per cent return and the contributions alone compound to well over $350,000 before the tax saving is even counted.