The G8 summit today has a number of agendas. Syria will be a massive distraction; EU - US trade is a red herring for much of the world and some of those attending, but tax havens and the need for transparency will be firmly on the agenda and is why I will be in the G8 press centre today at the invitation of the IF campaign and Downing Street. In that case it's important to be clear what the issues are, and for that we need to go back to basics.

The essence of fair taxation is simple: it is that:

1) The tax base is as wide as possible, covering as much economic activity as is achievable

2) The resulting income, gains, sales or other activity to be taxed is clearly identified and identifiable (which are not the same thing: the former is saying what should be taxed as clearly as possible, the latter is finding it once it has been defined)

3) The tax base should be taxed once, and once only

4) The tax rate should take into account capacity to pay and the marginal utility of the tax base to the taxpayer: in other words progressive taxation has to apply within the system, at least overall

5) Proper account has to be given for the tax paid

You could elaborate that list: I think it probably sufficient. And within that definition tax havens are an aberration.

First they make it hard to define the tax base because transactions that really take place within a country are artificially removed from it.

Second, by providing secrecy they go out of the way to make the tax base hard to identify.

Third, they ensure that at least some of the tax base is not taxed by hiding it from view.

Fourth, but providing bolt holes for wealth - whether personal or corporate, and also now for internet based sales, they make it harder to ensure that tax is applied progressively. Worse, it is all too often clear now that those with greatest capacity to pay do not do so, making the tax system regressive and so socially unjust by penalising those with a lesser capacity to pay with a greater burden than they should suffer.

Lastly, by creating opacity they create a climate of mistrust in the tax environment between companies, individuals and companies and governments and taxpayers, all of which create costly economic distortions that result in the misallocation of economic and social resources at cost to us all.

That's why tax havens matter.

It's why we need transparency.

These are the reasons for international tax reform.

That's why I have campaigned on these issues for over a decade.

That's why the IF campaign thinks this important.

It's why this issue is on the G8 agenda.

It's why we want a result today.