The self-assessment taxation system has become a "self-evasion" one, representatives of the MSF and ATGWU trade unions claimed yesterday.

They were presenting a joint pre-Budget submission, Investing in a Shared Future, which calls for the introduction of a new 15 per cent tax rate for the first £2,000 of a single person's earnings.

Mr Jerry Shanahan, MSF deputy national secretary, said the self-employed were underpaying tax at the same time as the corporate sector was receiving disproportionate tax cuts. The Minister for Finance, Mr McCreevy, would have an extra £1.9 billion in drafting the 1999 budget, he said.

The two unions were looking for equity in the taxation system, overdue for 20 years, he added.

"Self-assessment has effectively become self-evasion," he said.

Since 1987, the income of the self-employed had increased by 85.7 per cent, or £2.2 billion, while tax revenue from this sector had only increased by 6.2 per cent or £36 million. Mr Michael O'Reilly, ATGWU regional secretary, said the unions were proposing that the level of capital gains tax be restored to 40 per cent, and that there should be a uniform corporation tax rate of 20 per cent, not the 12.5 per cent planned by the Government.