I've not just been thinking about the credit crunch this week. One of the big corporate tax avoidance schemes, cited by Dave Hartnett as an example of the dangers of tax avoidance, is about to hit the headlines again.

It's about 'tax-efficient off-market swaps'. It's worth £1bn, used by mega-corporates, and a test case judgment involving Prudential comes up in the next few days, my colleague Nicholas Neveling has been told.

As far as I can tell, it's all about the structure of foreign exchange deals, and being able to claim the premium for such exchanges in a clever tax efficient way. Perhaps one of you readers, better versed in tax than me, could give a better explanation?

I thought it worth bringing up here because Dave Hartnett, when talking to a Lords committee after the disclosure rules were introduced a few years back, had a bit to say about the schemes. It's worth reading, here.