It's been widely assumed that the data the Revenue is using as the basis of checking declarations under the UK 'tax amnesty' is that supplied to them by the leading five UK banks, secured under what are called s20 notices, i.e. against their will.
Well placed sources, whose information I have no reason to doubt, tell me that's not entirely true. Some is from routine information supplied to HMRC under information exchange arrangements under the EU Savings Directive. Now that opens up a whole new ball park:
1) This means many more territories are involved, both onshore and offshore
2) By no means all those on whom the Revenue are holding data will in that case be getting letters from High Street banks to tell them that the Revenue have information on them.
My suspicion is that there are a great many people who have accounts in other EU countries where tax might even have been paid at source but where, for example, higher rate liabilities have been omitted from UK tax returns who might also need to think about checking past data. Remember, in most cases data is now being automatically exchanged between EU countries.
Oh, and just for fun, some of the information supplied has, apparently, nothing to do with taxable information as such, but is credit card data, holders of which may also not get a letter from a bank.
In that case, as my source and I agreed, all things considered it looks like the Revenue's tax take on this is going to be much higher than has been publicly suggested.