Very interesting debate. I could live with amending the process... but for now I'm still in favor of officially scrapping it, and tell realism to go swallow razor blades.
I've drafted a tax bill which I've now held off from introducing now this is on the table. I've done my best to cost the bill, taking guestimates based on US data as to how much it would cost, and how that matches with economic growth and so on. I don't see the point, if this amendment passes, of doing any costing on it at all - just proposing the tax cut and to hell with the cost and impact on our expenditure.
But if I were to introduce the bill without any figures on the cost (on the basis that without a budget there would be no need) I know the first question I would be asked ; 'What's it gonna cost'
If people can ask questions about how much a bill will cost they should be able to ask how much the government costs.