The Federal Budget is $2.4 billion further in the red on the back of falling corporate tax collections and despite a clampdown on spending.
Figures released by the Finance Department last night showed that revenues to the end of December were almost $4 billion below what was expected to meet the forecast surplus of $1 billion.
Treasurer Wayne Swan abandoned his pledge late last year to deliver a surplus, suggesting the Budget was on track for a deficit of at least $5 billion.
Resources rent taxes, which include the minerals resource rent tax and its petroleum counterpart, were supposed to earn $5.5 billion this financial year. But halfway through the year they had earned only $1.1 billion, with the MRRT's share just $126 million.
But company tax continues to be the biggest black hole in the Budget.
Through the first six months of the 2012-13 financial year, the corporate sector paid $31.2 billion in tax. The Budget needed the sector to cough up $73 billion to reach the $1 billion surplus.
December 2012's corporate tax collection last year was almost $1.4 billion lower than what was collected in December 2011.
The overall shortfall in revenue, however, did not grow between October and December.
Income taxes have held up while the States may gain a small goods and services tax windfall with the consumption tax slightly ahead of forecasts.
The Government's efforts to pull back spending appear to be working.
Total spending to the middle of the financial year is $1.4 billion lower than forecast at the mid-year Budget update.
A spokeswoman for Finance Minister Penny Wong said the figures showed the challenges facing the Government.
Company profits had been affected by weakness in global conditions and the high dollar had pushed government receipts lower than expected, she said.
"This Government will continue to exercise spending restraint, even in the face of ongoing volatility and uncertainty in the global economy," the spokeswoman said.