Michael Noonan (Limerick City, Fine Gael) | Oireachtas source

It is not so much based on the growth estimate as on the flow of taxes. Growth is tenuous because it is a projection. The bulk of what we are talking about is money already collected. It is the €970 billion in advance of budget at the end of August. That is not put in a safe. As it comes in, because it is not spent, it begins to reduce the deficit. If the Deputy looks at the statement on the August Exchequer returns he will see that the deficit was €1.3 billion below budget forecast at the end of August this year. It is progressive. As the taxes come in the deficit goes down. The deficit is probably somewhere below €4 billion at this point in the year, and we can project where it will land at the end of the year. I use the word “broadly” to cover the fact that it might be €50 million or €100 million above or below the line, but in general terms approximately €2 million has come in that was not estimated. That means far fewer cuts.

See this speech in context