I am speculating but it was a five year contract that he served out in full. He was paid $500,000 in the final year of the contract but no other extra payments in any other year.
Senate submissions include full financials for 2011-2016
2016: $775,000 salary + $0 incentive (page 33, note 26i)
2015: $775,000 salary + $230,000 incentive
2014: $735,885 salary + $0 incentive - (but +$76k fringe benefits) note states
he was eligible for incentive payment but chose to forego it.
2013: $696,779 salary (13 months) + $0 incentive - note states
he was eligible for incentive payment but chose to forego it
2012: $1,291,844 salary + $895,945 incentive (JON)
2011: $762,500 salary + $180,000 incentive (JON)
2010: $737,500 salary + $385,000 incentive (JON)
Seems this is a yearly thing based on some undisclosed KPIs being met. I'm guessing they fucked off all together or greatly reduced any golden handshake for 5 years of hardship after the JON uproar getting 2 mill in his final year; but i could be wrong.
Maybe the only KPI big bill met last year was surviving till the end OR maybe he just met all his targets which was a '75% made up scorecard pish' that they spout in the annual report. I guess we will never know the breakdown/reasoning of the 500k