The Minister for Public Expenditure and Reform has told RTÉ's News at One that half of the upcoming Budget spend is already allocated, leaving a balance of €2.7 billion which "will have to fund everything else".
Minister Michael McGrath also said that a figure for the separate cost of living package has yet to be finalised.
"No decisions have yet been made," Mr McGrath said with regard to whether the budget will include a proposed €15 across-the-board welfare payments rise, a suggested 30% income tax rate, tax relief for landlords or tax credits for renters.
"The good thing is that we have agreed the parameters of the Budget in the Summer Economic Statement.
"We outlined the total package of €6.7 billion for the normal annual Budget for 2023 with a small element of it being brought forward into the current year.
"Almost €5.7 billion will be on the spending side, just over €1 billion on the taxation side.
"Alongside that package of €6.7 billion there will be a separate package of one-off measures. There is some scope to go beyond that €6.7 billion in the context of once off cost-of-living measures," he explained.
"The €5.7 billion that I have on the spending side, over half of that is already pre-committed. The balance of €2.7 billion will have to fund everything else.
"That includes public service pay costs, housing, health care, social welfare, education, childcare and justice," Mr McGrath said.
He added that a decision has yet to be made if social welfare increases will be across the board.
"That is a detailed decision that is yet to made. There are currently different rates attached to different social welfare payments. The state pension for example attracts a higher rate compared to Job Seekers, Carers Allowance and Disability Allowance.
"From where I sit, I must make sure that on the spending side we stick to the parameters that we have agreed. It means that we have to prioritise. Everything can't be the priority," he said.
Referring to the impending cost-of-living package, Mr McGrath said there is "some scope for a significant package" as public finances "have been well managed".
"But we will have to strike a balance between targeted measures which are focused on those who are carrying the heaviest burden in relation to inflation and energy costs. In the next number of weeks, we’ll finalise what the overall envelope is".