Mark Lee of the Tax Advice Network has secured a copy of the letter HM Revenue & Customs has sent to UK based banks regarding accounts (including assets portfolios) their banks manage on behalf of UK resident persons (including companies, trusts, partnerships and more besides) where the funds are held outside the UK.

Note, as I suggested earlier, this requires disclosure if the documents are in the possession or power of a UK bank. I have no doubt that a UK parent has power over all its subsidiaries.

The data required is extensive.

People who do not voluntarily come forward and declare any undeclared assets they have offshore will, I think, be most unwise.

Of course there will be those who will try to rely on their luck. And they may still believe banks will fight back. I think there is little chance of banks winning that argument now. And for those banks who have adopted IFRS 8 and have not treated their offshore subsidiaries as separate entities I’d think very hard before saying you have no power, because you have very publicly already said you have.

The extraordinary thing is - with this request HM Revenue & Customs is basically saying it wants Automatic Information Exchange. So why not publicly support it, and even demand it from the OECD in Mexico next week?