In the report, the Comptroller and Auditor General observed that:

"The efficiency with which the Revenue deals with tax returns for the estates of those who have died has improved: it processes 66 per cent more cases than in 1999, and has taken on additional work, with a broadly similar level of staff. It conducts compliance enquiries on around 5 per cent of those tax returns, securing an additional tax yield of £126 million in 2003-04."

"The Revenue has also improved the way it singles out cases for checking, making greater use of data held in other parts of the organisation and checking for particular risks such as undeclared gifts or under-valued houses."

However, in a statement released last week, Chiltern's director of estate planning and trusts, Ian Maston suggested that:

"This two thirds increase demonstrates just how many people are now being caught by the current inheritance tax threshold of £263,000."

He continued:

"The pain for many is made worse by the impending application of the government’s pre-owned assets legislation which comes into force next April. From then, a new tax will apply to assets people have given away where the original owner gets a benefit from them."

Mr Maston concluded by observing that:

"Anyone considering their tax position needs to be very careful with their planning at this stage since retrospective legislation appears to be firmly on the Treasury’s agenda. The chance of the rules changing one, two, three or even ten years down the road raises the possibility of an unforeseen tax bill."