The latest statements from Treasury on the state of the government's books show income from taxation is $1.1 billion less than forecast.
Treasury has released financial statements for the six months to December last year.
It says the corporate tax take is nearly 12%, or $564 million, lower than forecast.
Treasury expects this corporate tax shortfall will persist through the next few years, as companies' profits drop as a result of the global downturn.
GST payments are also down, reflecting a more rapid drop in consumption than expected.
The government's operating balance, which includes investment gains and losses, is in deficit by $6.2 billion.
The pre-election forecast in October had predicted a surplus.
