The federal government has signalled spending cuts will be made when the budget is unveiled on May 10.
Senator Wong said key revenue forecasts had changed since Treasury released its mid-year economic and fiscal outlook in November.
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Company tax revenue have fallen by $3 billion while personal income tax receipts have dropped by $1 billion.
"These are the facts. It's going to be a tough budget," Senator Wong told ABC Television on Sunday.
"There's been a hit on revenue."
Senator Wong said the budget needed to be tough.
"It won't necessarily be a popular budget but it will be a budget that's very focused on the short and long-term needs of the economy," she said.
"We've got some short-term softness and that's as a result of a number of factors, the floods, the cyclone but also a cautious consumer and a strong Aussie dollar."
During summer, Queensland suffered from floods and a severe tropical cyclone.
Senator Wong has rejected suggestions the government's aim of getting the budget back into surplus by 2012/13 was a political benchmark.
"I don't agree with that," she said.
