The amount of tax that HMRC believes has been underpaid by wealthy individuals relating to trusts has jumped by 32% in the past year, to £80.3m, up from £61m the previous year, according to international law firm RPC.

RPC said the revenue had also sharply increased its estimate of the amount of money that it suspected has been underpaid by wealthy individuals through the avoidance of stamp duty land tax - that has jumped 24% to £70.7m, up from £48.3m in 2020/21.

It added that HMRC was making increasing use of information shared by overseas tax authorities to identify wealthy individuals who may have underpaid tax by using  trusts that have been established overseas.

"The process of information exchange under the common reporting standard, means that HMRC now receives data from over 100 tax authorities around the world. HMRC can then cross reference this against tax returns received from individuals," it said.

Taxable trusts can be created by deed or otherwise, and include those that are liable for income tax, capital gains tax (CGT), inheritance tax (IHT), stamp duty land tax, and stamp duty reserve tax. It also includes those liable for land and buildings transaction tax (for relevant assets in Scotland) and land transaction tax (for relevant assets in Wales).

The registration deadline for taxable trusts typically mirrors the self-assessment deadline of 31 January following the tax year in which the tax charge occurred.

Adam Craggs, partner and head of tax investigations at RPC said when HMRC increased its estimate of tax avoidance or evasion in a particular area, an increase in investigations focussed on that area could be expected.

"HMRC now has access to a wealth of information regarding assets held overseas by HNWs and it would be surprising  if it did not make full use of this information. "

RPC added that HMRC was also looking more closely at stamp duty tax returns to identify cases which it considered relief has been wrongfully claimed. "This can include claims for multiple dwellings relief. HMRC believes that up to a third of claims for this type of relief are incorrect."

Constantine Christofi, senior associate at RPC said: "Rising house prices has led to greater stamp duty liabilities, particularly at the higher end of the property market, which has incentivised some people to seek to mitigate their tax liability.

"HMRC is determined to claw back any tax which it believes has been underpaid by wealthy individuals who have purchased high value residential properties."