Professor Michael McMahon:

This is not based on projection, but on what the Government will spend. If it chooses not to increase social welfare at all and inflation has gone up, reducing the real value of that, core spending will not go up. When the Government chooses to increase it in line with inflation or with any other policy measure, then spending goes up and that is counted as extra spending.

I do not want to get stuck in semantics here but the point on the revenue is that these are often labelled as tax cuts but what they actually do is maintain an existing tax system. It is not about "We have projected how much", but-----