Headline numbers: Significant zeros in the Tory dossier
Earlier in the week, I looked at some of the bigger figures in the Conservatives' 82-page dossier on Labour spending plans - mainly things that were supposed to cost an extra £1bn or more.
Today I'd like to have a look at some of the smaller figures in the dossier, in particular some of the zeros.
One of the most prominent zeros is the amount of money the Conservatives say would be raised by increasing the top rate of income tax from 45p to 50p on incomes over £150,000.
There's a lot of history behind this figure - when the government cut the rate from 50p to 45p it said that would reduce the direct tax take by £110m a year and the Office for Budget Responsibility (OBR) agreed.
Incidentally, some Conservatives say that lowering the top rate has actually increased the tax take. While there is some economic theory to back this up it is by no means undisputed.
But research from HM Revenue and Customs concluded that considerably more than £110m had been lost through other forms of taxation such as VAT as a result of the higher rate, hence the zero rating.
But Labour points to warnings from the OBR about the uncertainty involved in putting a value on the tax change.
Labour says the 50p tax raised an extra £3bn before account was taken of people changing their behaviour to avoid the tax and that the government should have found ways to tackle the avoidance instead of cutting the tax.
Much of the uncertainty is to do with how short a period the policy was in place, which allowed people to move income away from years with the 50p top rate.
Labour hasn't yet said how much it expects to raise from the 50p rate, but I think we can reasonably assume it will predict a positive figure.
While we're looking at zeros, abolishing the New Homes Bonus and reallocating the funds within local government is given as both a cost of £1.17bn and a revenue raiser of £1.17bn.
There are plenty of other zeros in the report, mainly for policies (or alleged policies) that would not take effect until later in the next Parliament.
One of those zeros is another hit for those earning over £150,000 a year, which would limit the amount of tax relief they can get on their pension contributions.
The Treasury gives it a zero for money raised because it says that even if it is introduced in an emergency budget straight after the election, it could not take effect for two years because individuals, companies and the government would need time to prepare for such a change.
Labour have said they would get the money in as soon as possible but that actually the Treasury had worked out that the policy would eventually raise more than it had expected.
So what do these zeros tell us about the forthcoming election campaign?
Well I already concluded that the costing exercise was jumping the gun a bit, coming several months before any manifestos have been published.
But all these zeros also highlight the importance of looking at the effect of a policy over a whole Parliament and not just the first year of it.