It is the largest tax-evasion settlement in history, according to George Osborne, who yesterday fleshed out a treaty with Switzerland which will ensure, he said, "that for the first time in our history money will be flowing from bank accounts in Switzerland to Britain rather than the other way around".
However, the Chancellor was immediately accused of doing a deal with potentially major league criminals in a bid to bring back 5bn of unpaid tax from Switzerland.
While the treaty with Switzerland had been announced and agreed in principle before, the amounts involved only emerged yesterday.
The measure for "bilateral co-operation" to ensure proper taxation of UK individuals with assets in Switzerland comes into force at the start of next year. It will be a boost to the Exchequer to the tune of 330m next year and a whopping 3.1bn in 2013-14.
As part of the agreement, the Government will agree not to pursue the tax evaders.
Some tax advisers asked which individuals and banks were behind the 3bn, and questioned the sources of the money.
Cormac Marum, an adviser at Harwood Hutton, said: "The point is that anyone who has hidden money in Switzerland and not disclosed it is a tax evader. That is a criminal offence. …