The rates scale, but the payment is not progressive. Eg as per the example from the ATO's site.
"Example: HELP compulsory repayment
Mitchell’s repayment income for the 2013–14 income year was $54,915, and the repayment rate for repayment income from $51,309–$57,153 was 4.0%. Mitchell’s compulsory repayment was $54,915 × 4.0% = $2,196.60"
In other words, if you earn 100K flat minus writeoffs etc, you will pay $8000 in HECS
Yeah, they have. They left 16K of my income out, which means i'd theoretically owe 2K less which explains why its so messed up and why the tax calculator wanted to give me a 7K refund.
However as per the example above, if Chants has earnt over $51309 she will owe minimum 2K. so if you earn 51K on your job they have no need to take out HECS, you earn a few hundred bucks somewhere else all of a sudden your tax bill jumps by 2K. In this case i'd be seeing a good accountant and trying to get your taxable income under $51309.