Your compulsory repayment is worked out once a year, from your whole repayment income — every job, side hustle and add-back combined. But withholding happens per employer, and each payroll system only sees its own numbers. Job A withholds as if Job A were everything; Job B does the same. Nobody is looking at the total, and the gap between the two views lands on you at assessment.
This is sharpest when the second job is small. A job paying under the $69,528 threshold withholds no HECS at all — correctly, from its own point of view — while quietly pushing your combined income deep into repayment territory.
| Main job | Second job | Combined income | Repayment on main job alone | Repayment actually assessed | The gap the second job created |
|---|---|---|---|---|---|
| $62,000 | $18,000 | $80,000 | $0 | $1,571 | $1,571 |
| $75,000 | $25,000 | $100,000 | $821 | $4,571 | $3,750 |
| $90,000 | $30,000 | $120,000 | $3,071 | $7,571 | $4,500 |
| $110,000 | $40,000 | $150,000 | $6,071 | $12,476 | $6,405 |
2026-27 compulsory repayment: main job alone vs combined income. Withholding at the second job in these examples is $0 of HECS.
Read the first row twice: $62,000 alone is under the threshold — no repayment, no withholding. Add an $18,000 side job and the assessed repayment is $1,570.80, none of which either employer has been collecting. That figure arrives as a debit on your notice of assessment.
The repayment can't be reduced — it's a function of your combined income — but it can be smoothed so it doesn't arrive as a surprise:
To size your own gap: put your combined figure through the repayment calculator, subtract whatever your payslips show being withheld across the year, and the remainder is what assessment will ask for.
Suppose the main job pays $75,000 with HECS withholding switched on, and the side job adds $25,000 with none. Combined repayment income: $100,000, assessed repayment $4,570.80. The main job's payroll is withholding towards a $820.80 liability — its view of your year — so the unfunded gap is roughly $3,750. Spread over 26 fortnights, that's about $144 a fortnight to set aside from the side job's pay. Do the same arithmetic with your own two numbers and the year-end debit becomes a planned transfer instead of a surprise.
If the second income is freelance or contract work on an ABN rather than a second payroll job, the blindness is total: there is no employer, no withholding of any kind, and the entire tax and HECS consequence of that income arrives at assessment. The repayment maths is unchanged — business income (after deductions) lands in the same repayment-income pool as wages — so the table above applies; the only difference is that nothing at all is being collected along the way.
Two practicalities follow. First, the set-aside discipline matters more: 15–17 cents for HECS on top of whatever you're putting away for income tax on the same dollars. Second, after your first assessment with significant untaxed income, the ATO may move you onto quarterly pay-as-you-go instalments for the tax side — those instalments don't cover HECS, so the study-loan portion stays yours to provision either way.
One common confusion to retire: the tax-free threshold declaration you make when starting a second job affects income-tax withholding only. Claiming it at both jobs under-withholds tax; it has nothing to do with the HECS gap described here, which exists even when every declaration is filled in perfectly. The two problems just happen to arrive on the same notice of assessment.
Every figure on this page is computed at build time by the same engine that powers the calculators on this site — nothing is typed in by hand, so the tables cannot drift away from the tools. The engine is checked against the ATO's published thresholds by a golden test suite that fails the build if any figure moves unexpectedly.