This is based on the fact that receiving payment in cash in order to escape tax could come under either the 'evasion' or 'hidden economy' types of taxpayer behaviour as defined by HMRC, the pair of which account for an estimated total of £8 billion in lost tax according to the most recent assessment of the tax gap by HMRC.
She said both of the government departments had failed to measure if the reliefs provided value for money, or had led to taxpayers changing their behaviour in the way intended, such as by increasing their saving or investing.
The revenue from such taxes is extremely hard to estimate because, like Labour's pledge to abolish non-domicile tax status, it is difficult to predict how taxpayers may change their behaviour as a result.
Lord Oakeshott, the Liberal Democrat peer who resigned as the party's spokesman in the Lords, said : "I agree with Bob – the time for remorse is past, but what British taxpayers need now is behaviour change from Barclays.
"Commissioner Andor shouldn't say that, his salary is paid in part by British taxpayers, and I expect better behaviour in the future".
That is what the reduction in the top rate from 50 pence to 45p would cost the exchequer, if this top 1% of taxpayers did not change their behaviour any way.
HMRC's specialist team gives it a better understanding of the tax affairs and behaviours of these taxpayers.
To simply hand over the money necessary to return them to solvency would abuse the taxpayer's trust, reward bad behaviour, and send a terrible signal to other bad financial actors out there.
Speaking to the Guardian, Willetts said the regulatory regime had already been improved: "The evidence you have in some specific cases appears to show unacceptable behaviour … "Students and taxpayers are right to expect a quality education service.
Second, no matter how good those people are, central banks are bound to fail eventually: the banking system is huge and complex, and now enjoys a taxpayer guarantee that both encourages risky behaviour and is hard to withdraw.
