Great Barrier Reef grant

During preparations for this year's budget, the government found itself with a problem no one had dealt with since 2008. It was awash with cash.

Courtesy of commodities prices, extra tax revenue was rolling in: in the 2017 budget, revenue for 2017-18 was forecast to be $444 billion. In December, that was upgraded to nearly $449 billion. But in March, actual revenue was tracking $5 billion ahead of that forecast.