The one thing to remember about tonight's budget is that it is just that - a budget. Leave aside some of the figures about what should be spent in the 12 months from 1 July and the rest is nothing more than one big guesstimate.
All those figures about the size of the deficit in 2010-11, 2011-12, 2012-13 don't actually mean anything. What actually happens is just as likely to be lower as higher - whether we look at the future estimates for revenue or spending, economic growth or anything else.
The only safe bet is that most of the figuring will turn out to be wrong.