The taxman was due to meet with the industry's professional bodies this week. The tax authority is expected to water down proposals to make accountants register tax avoidance schemes they intend to sell to clients.

Accountants have been fighting hard to win clarification on the proposals, which were first announced in the finance bill, because they claimed the Revenue would be flooded with registrations.

Mark Lee, chairman of the ICAEW tax faculty and director of tax services at WJB Chiltern, said: 'I anticipate the regulations will be amended before they are fully finalised. They will want to amend the regulations to limit the extent to which firms will be making vast numbers of precautionary statements.'

Partners of the major accountancy firms said that the Revenue would be swamped with forms from firms because the new regulations had not made it clear what must be disclosed.

Estimates put the cost of complying with the new rules at £1m per firm.

John Whiting, tax partner at PricewaterhouseCoopers, said: 'We don't know what the rules are that we're trying to comply with. The difficult part is trying to find out what has to be disclosed.'

As costs rise for the firms, so will the fee they charge their clients, as some of the burden is passed on. Experts have said clients could see their fees double in some cases.

The consultation period on the proposals ends on 30 June.