The very wealthy are paying less tax while ordinary taxpayers see their bills increase, an influential parliamentary committee has warned.

The Public Accounts Committee said Government’s claims to be cracking down on tax avoidance by the richest “just don’t stack up” and that the shift was happening despite supposed moves to make the wealthy pay their fair share.

A new investigation by the cross-party committee found that the tax take from very wealthy people had fallen by £1 billion since HMRC set up a dedicated “high net worth” unit to chase unpaid or missing tax from the rich.

Meanwhile the income tax paid by all other taxpayers has risen by £23 billion over the same period.

“HMRC's claims about the success of its strategy to deal with the very wealthy just don't stack up,” Meg Hillier, the MP who chairs the Public Accounts Committee said.

“The tax take for this group of people has fallen by £1 billion since HMRC set up its dedicated unit. At the same time, income tax paid by everyone else has risen by £23 billion.”

The committee’s investigation report says that HMRC’ has eroded public trust in the tax system with a “lack of transparency” and that the treatment of the richest could be “cosy”.

The richest are given help with their tax affairs not available to other taxpayers, the report warns. The MPs call for HMRC to conduct a “formal evaluation” of the “high net worth unit” and report it findings back to the committee.

Ms Hillier continued: “Cosy terms such as ‘customer relationship manager’ and HMRC’s reluctance to be open add to the picture of arrangements that, while beyond the reach of ordinary taxpayers, are also ill-suited to the increasingly sophisticated methods the super-rich can use to reduce the tax they pay.

“If the public are to have faith in the tax system then it must be seen to have fairness at its heart. It also needs to work properly. In our view HMRC is failing on both counts.

“HMRC must play a stronger role in identifying tax measures which are not being used as Parliament intended and push harder for reform where the rules are open to abuse.”

HMRC told the committee that the changes in tax revenue collected over the period examined was influenced by people shifting income between tax years to take advantage of the cut in the top rate of tax from 50 per cent to 45 per cent.

10 of the biggest tax havens in the world Show all 10 1 /10 10 of the biggest tax havens in the world 10 of the biggest tax havens in the world Luxembourg There are an estimated £2.5 trillion shares of mutual funds registered in the Grand Duchy, £1 trillion of which cannot be traced to an owner 10 of the biggest tax havens in the world Cayman Islands The Cayman Islands contain 6% of the world's total banking assets, but just 0.000008% of its population 10 of the biggest tax havens in the world Isle of Man David Cameron has said the Isle of Man, where there is no corporation, capital gains or inheritance tax, should not be considered a tax haven 10 of the biggest tax havens in the world Jersey There are over £3.5 billion assets per square mile on the self-governing Channel Island 10 of the biggest tax havens in the world Ireland Ireland made headlines last year when it emerged Apple was registered in the country in order to dodge over £40bn in taxes 10 of the biggest tax havens in the world Mauritius The Mauritian government notionally charges corporation tax, but companies can easily make this back through generous tax credits for foreign businesses 10 of the biggest tax havens in the world Bermuda Google holds more than £30bn in offshore cash reserves, primarily via Bermuda 10 of the biggest tax havens in the world Monaco A popular domicile for super-rich private individuals, Monaco has the most expensive property in the world. £1 million will buy just 225 square feet 10 of the biggest tax havens in the world Switzerland Switzerland has such secretive banking laws that it took until the 1990s to secure the release of Nazi cash reserves 10 of the biggest tax havens in the world Bahamas David Cameron's father ran an offshore fund which hired Bahamas residents to complete paperwork, thus dodging British tax bills

In response to the report, an HMRC spokesperson said there was "absolutely no special treatment" for the wealthiest individuals.

“The vast majority of people in the UK pay all the tax they owe and today the top one per cent of earners pay more than quarter of all income tax," he said.

"There is absolutely no special treatment for the wealthy, and in fact we give them additional scrutiny, with one-to-one marking by HMRC’s specialist tax collectors, to ensure that they pay everything they owe, just like the rest of us do. We have secured an additional £2.5 billion from the very wealthiest since 2010.