I have sought before to explain how the Barnett formula works. It is the way of determining increases in Scotland’s bloc grant money each year, based on the increases in England for similar programmes. Those who think the debate is simply whether you are pro or anti Barnett are misjudging the issue.
The bigger issue is what is the base grant? Someone has to decide which items of spending are devolved to Scotland that need bloc grant. They now also will need to decide what reduction you make to the bloc grant to allow for Scotland directly setting her own tax rates and collecting her own revenues for some taxes. Is the own tax simply going to be a general deduction from bloc grant expenditure? Are some items of spending going to be taken from the bloc grant and allocated to own taxation? Those methods produce different answers.
Presumably a fair settlement for the Union as a whole has to allow Scotland to spend extra if she raises extra from setting higher or lower tax rates that raise more revenue.If this does not happen what is the point of more fiscal independence. I have no problem with Scotland wishing to raise more tax to spend more. It will be an interesting experiment. Conversely Scotland will have to accept that if she chooses to raise or lower rates in ways which cut the revenue, that should mean Scotland spends less. England will not accept an asymmetric system, where England pays what Scotland does not raise.
The disadvantage of hypothecating particular spending to Scottish tax is they will then lose their right to more money from England to support those services, which they enjoy at the moment. The advantage is the other services will be fully underwritten by the rest of the UK. There is a justice in some part of the Scottish budget giving Scotland full control over both the spend and the amount of tax they collect to pay for that part.
The other route is to deduct the present amount of tax revenue raised in Scotland from the taxes that are being devolved, and to increase that amount annually by the amount those tax revenues go up in the rest of the UK – a new Barnet formula for revenue.This works fine unless and until the rest of the UK changes the rates or does something structural to the tax, when the grant deduction would need to be recalculated somehow. There might be other indices which could be used to approximate the tax revenue assumed in the calculation – e.g. some factor of GDP growth which was based on the past buoyancy of that tax.
Your thoughts would be appreciated.