How salary sacrificing to super works
A salary sacrifice arrangement redirects part of your pay into super before income tax. The sacrificed amount skips your marginal rate (30%, 37% or 45%, plus 2% Medicare levy) and is instead taxed at 15% inside your fund. The saving is the gap between those two rates — which is why the strategy is powerful in the 30%+ brackets and weak below them.
The HECS catch: sacrificing doesn’t shrink your repayment
HECS-HELP repayments are based on repayment income, which takes your taxable income and adds back reportable super contributions. Sacrifice $10,000 from a $100,000 salary and your repayment is still assessed on $100,000 — about $4,571 in 2026–27, not the $3,071 a naive calculation on $90,000 would suggest. That’s a $1,500 difference many super-fund calculators silently get wrong.
The practical sting: your employer withholds HECS based on your reduced PAYG salary, so too little may be set aside during the year — the shortfall arrives as a bill with your tax assessment. If you sacrifice and have HECS, consider asking payroll for extra withholding or putting the difference aside.
Mind the concessional cap
The cap counts your employer’s 12% super guarantee plus your sacrificed amounts. On a $150,000 salary, employer super is already $18,000, leaving $14,500 of headroom under a $32,500 cap. Go over and the excess is effectively taxed at your marginal rate — undoing the benefit. If your super balance is under $500,000, unused cap from the previous five years can be carried forward, which is the main legitimate way to contribute more in one year.
When salary sacrifice is — and isn’t — attractive
- Strongest: 37–45% brackets, no near-term need for the cash, cap headroom available.
- Solid: 30% bracket — a 17c-per-dollar saving compounding for decades.
- Weak: income mostly in the 15% bracket — the wedge nearly vanishes; after-tax contributions plus the government co-contribution often beat it.
- Cautions: money is locked until preservation age; Division 293 (extra 15% for incomes above $250,000); HECS unchanged; sacrificed pay can affect some lenders’ borrowing assessments.
Frequently asked questions
How much tax do I save by salary sacrificing into super?
Sacrificed amounts skip your marginal tax rate (plus 2% Medicare levy) and are instead taxed at 15% inside your fund. On $100,000, sacrificing $10,000 saves $3,200 in income tax and Medicare levy; after $1,500 contributions tax, $8,500 lands in super at a cost of only $6,800 in take-home pay.
Does salary sacrificing reduce my HECS repayment?
No — and this catches many people out. HECS is calculated on your repayment income, which adds reportable super contributions back to your taxable income. Sacrifice $10,000 from a $100,000 salary and your HECS repayment is still calculated on $100,000. Your employer may even under-withhold for HECS because your PAYG income looks lower, leaving a bill at tax time.
What is the concessional contributions cap?
The annual limit on before-tax super contributions — your employer’s 12% super guarantee plus anything you salary sacrifice, combined. Exceeding it means the excess is effectively taxed at your marginal rate instead of 15%. The calculator shows your cap usage; if you have unused cap from the past 5 years and a super balance under $500,000, carry-forward rules may let you contribute more.
Is salary sacrificing worth it on a lower income?
The benefit equals the gap between your marginal rate and 15%. At the 30% bracket (plus Medicare) you save about 17c per dollar; at the 15% bracket the saving is close to zero, and below the tax-free threshold sacrificing actually costs you. Lower earners are often better served by after-tax contributions and the government co-contribution instead.
What’s the catch with salary sacrificing?
The money is preserved: you generally can’t touch it until you reach preservation age. Other trade-offs: HECS repayments don’t fall, Division 293 adds 15% extra contributions tax for very high earners (income + concessional contributions above $250,000), and a lower PAYG salary can slightly affect borrowing-power assessments with some lenders.
How do I set up salary sacrifice?
Ask your payroll or HR for a salary sacrifice arrangement into super — it must be agreed prospectively (for future pay, not pay already earned) and documented. There’s no ATO form; it’s an agreement between you and your employer. Check that your employer still pays the 12% super guarantee on your pre-sacrifice salary, which has been the legal requirement since 2020.
See the flow-through to your payslip in the Income Tax Calculator, or check your repayment in the HECS Repayment Calculator.
Calcroo provides estimates for general information only — not financial, tax or legal advice, and super strategy depends heavily on personal circumstances. Caps, rates and thresholds: confirm at ato.gov.au. Consider advice from a licensed financial adviser before changing contributions.