Calculator
Superannuation Contribution Optimiser
Superannuation Contribution Optimiser
Rent, dividends, business income
12% SG on your ordinary earnings
Non-concessional - from money you've already paid tax on
Unused concessional cap space from the last five years
Concessional cap $30,000 (2024-25 onwards). Carried-forward caps unlock when your total super balance was under $500,000 at the previous 30 June. Division 293 adds 15% when income plus concessional contributions exceed $250,000. The government co-contribution matches 50% of personal contributions up to $500 for incomes under $58,445, and LISTO refunds contributions tax for incomes up to $45,000.
Total Tax Benefit This Year
$1,700
Strategy Verdict
Your $21,400 of concessional contributions saves $1,700 in tax versus taking it as salary (32% now versus 15% inside super). Your balance under $500k unlocks $18,600 of carried-forward caps, so total headroom is $27,200 - consider a larger deductible contribution before 30 June.
*Uses 2024-25 caps and thresholds ($30,000 concessional, $120,000 non-concessional, $500k carry-forward balance limit, $250k Division 293 threshold). Caps index over time; check the ATO before acting. Educational only, not financial or tax advice.
Every Dollar Into Super Has a Different Price Tag
Australia pays you to save through super — but the payment depends on how and when each dollar arrives. Concessional contributions (salary sacrifice, deductible personal contributions and employer SG) enter at a flat 15% instead of your marginal rate: for someone on $95,000 that is roughly 17 cents saved on every dollar diverted. Non-concessional contributions from already-taxed money earn no upfront deduction but grow tax-sheltered. Layered on top are targeted boosts most people never check for — carried-forward unused caps that let catch-up contributors exceed $30,000 in one year, the government co-contribution matching personal contributions 50 cents per dollar for low incomes, LISTO refunds for under-$45,000 earners, and the Division 293 surcharge quietly clawing back the advantage above $250,000. Getting this right is worth thousands annually. The common failures are symmetrical: high earners overshooting their cap and having excess taxed at full marginal rates anyway, while eligible low-income earners leave co-contributions and LISTO unclaimed because they require nothing more than making a contribution and lodging a return. This calculator assembles your complete picture — employer SG, planned sacrifice, personal contributions, banked carry-forward room and total balance — then prices every lever at once: the arbitrage earned, headroom remaining, surcharges triggered, and government money available.
Caps, Thresholds and the Arithmetic of Each Lever
Concessional contributions are capped at $30,000 per financial year. Every sacrificed dollar saves your effective marginal rate — bracket rate plus 2% Medicare — minus the 15% contributions tax super deducts, so a middle-bracket earner banks about 32−15 = 17 cents per dollar while a top-bracket earner banks nearly double that. Your total super balance below $500,000 at the previous 30 June unlocks unused caps from up to five prior years, letting a returning-to-work parent or newly profitable contractor inject several years' worth at once. Exceeding what your cap space allows triggers excess-concessional treatment: the overage is released from super and taxed at your marginal rate with an earnings charge — converting the strategy into pure loss. The targeted programs follow their own tests. Division 293 adds a 15% charge when combined income for surcharge purposes plus low-tax contributions exceeds $250,000 — note that contributing more can itself trigger it, which the calculator nets against the arbitrage. The co-contribution pays 50% of personal after-tax contributions up to $1,000, phasing down between $43,445 and $58,445 of total income and requiring at least 10% from employment. LISTO quietly refunds the 15% contributions tax for incomes up to $45,000, capped at $500. Each test runs independently; optimisation means satisfying all of them simultaneously rather than maximising any single line.
Expert Insights
Check Your Cap Space Before June, Not After
Employer SG counts toward the same $30,000 cap as your own sacrifices, and multiple jobs or overtime spikes can silently consume headroom. Before committing to a salary-sacrifice figure, add expected SG to intended deductible contributions and confirm the sum fits — including any carried-forward room you actually qualify for. The ATO's myGov portal shows your live cap position; five minutes there prevents the worst outcome in super planning, which is deliberately contributing money that gets taxed worse than salary.
Carry-Forward Is a Timing Weapon, Not Free Money
Banked unused caps shine in lumpy-income lives: the contractor with a windfall year, the parent returning after leave, the seller of a business facing a large assessable gain. Making a huge deductible contribution in a high-bracket year and paying 15% inside super beats spreading contributions across low-income years where the deduction buys little. But eligibility hangs on the sub-$500,000 balance test each 30 June — crossing that line permanently forfeits future carry-forward access, which occasionally justifies accelerating non-deductible strategies instead.
Division 293 Changes the Sacrifice Math Without Ending It
Above $250,000 combined income, concessional contributions attract an extra 15% — taking the total to 30%, still below the 47% marginal rate for those earning enough to be near the threshold. The deduction usually remains worthwhile, but the margin halves and the interaction matters: sacrificing more income can pull you below the threshold next year even as it triggers the charge this year. Model both years together rather than optimising one return in isolation; sometimes deferring a contribution twelve months preserves tens of thousands of cap space at better tax treatment.
Actionable Tips
- 1
Nominate Deductible Personal Contributions in Writing
Personal contributions only become concessional — and only earn the deduction — if you lodge a valid notice of intent with your fund and receive acknowledgement before lodging your tax return or withdrawing the money. Missing the form is unrecoverable: the contribution stays in super but taxed as non-concessional, forfeiting the entire arbitrage. Set the notice the same week you make the contribution; funds process acknowledgements within days.
- 2
Time the Sacrifice to Your Pay Cycle Cap-Safely
Salary sacrifice agreements must be struck prospectively with your employer — asking payroll to redirect last month's bonus does not qualify. Confirm whether your employer includes SG on sacrificed amounts (some packages reduce SG accordingly), then divide your annual target by remaining pay periods and let it run automatically. Mid-year cap reviews catch drift from bonuses or rises before they breach the ceiling.
- 3
Harvest the Government Money You Qualify For
Co-contributions and LISTO require exactly two actions: make an eligible contribution and lodge a tax return — no separate application exists, yet billions go unclaimed. If household income sits near the thresholds, even a small personal contribution earns a guaranteed 50% instant return unavailable anywhere else in finance. Check eligibility before assuming you earn too much; total income includes reportable super amounts and business income, so the test surprises people in both directions.
Real-World Examples
Karen Deployed Five Years of Banked Caps
Karen returned to full-time work at 44 after eight years raising her children, carrying $180,000 of accumulated unused concessional caps and a $310,000 balance. With her consulting income spiking past $160,000, she made a $120,000 deductible contribution across two financial years using carried-forward room, cutting her assessed taxable income sharply both years while the money compounded at super's 15%. Her accountant called it the largest single-year tax saving she had processed for a sole trader.
Devraj Stepped Around Division 293
Devraj's promotion to $240,000 plus SG put him within reach of the $250,000 Division 293 threshold, and his instinct was to stop sacrificing entirely. Modelling showed his planned $20,000 of concessional contributions triggered roughly $2,400 of extra charges yet still saved more than that against his 47% marginal rate — and that keeping income lower preserved next year's position. He trimmed rather than abandoned the strategy, splitting contributions across the threshold boundary years.
Sophie Claimed Money She Never Knew Existed
Sophie, a part-time pharmacy assistant earning $38,000, made a $600 voluntary contribution after reading about the co-contribution rules. The government added $300 — a risk-free fifty percent return — and LISTO separately refunded her contributions tax on top. Three consecutive years of the same routine built her super faster than her SG alone would have, purely by claiming programs that required no application beyond her normal tax return.
Glossary of Terms
- Carry-Forward Contributions
- Unused concessional cap space from the previous five financial years, accessible when your total super balance was under $500,000 at the prior 30 June.
- Division 293 Tax
- An additional 15% charge on concessional contributions when combined income plus low-tax contributions exceeds $250,000 in a financial year.
- LISTO
- The Low Income Superannuation Tax Offset - a refund of contributions tax up to $500 for workers with income up to $45,000 who receive employer SG.
Frequently Asked Questions
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Ivy Sinclair-Wren
Financial Chaos Analyst
Ivy Sinclair-Wren is a Financial Chaos Analyst covering investing, AI, wealth psychology, and the emotional consequences of opening finance apps during market crashes. Based in Melbourne, she specializes in demystifying the Australian tax code and helping users navigate the intersection of spreadsheet logic and human irrationality.