I don't see see how this deals with one important aspect of government: the unexpected. Would the government have been unable to do anything about 9/11 at all until the next year's tax round, or about the banking crisis? In the latter case, do they only have one opportunity a year to deal with any issue that might arise? Ok, you may say, there needs to be a contingency fund, the size of which is also voted for as part of this scheme. Who decides what that can be spent on? And how do we know it is big enough in the first place?