"We could have a negative list (of services) at some point of time. But it is the prerogative of the Finance Minister," Parthasarathy Shome, adviser to Finance Minister, said here at a post-budget meeting of Confederation of Indian Industry.

In defence of the Union Budget for 2005-06, Shome said the objective of tax rationalisation was to provide a level playing field for service providers.

Service tax covered everything except a few items and there was a need to assess the service component in the remaining areas, he said.

"We have expanded the coverage but kept tax rates intact," Shome said, adding the threshold was increased to clean up the service tax system.

Chidambaram had extended the tax net to 21 more services for mopping up Rs 17,500 crore (Rs 175 billion) next year.

Both Shome and revenue secretary K M Chandrasekhar also sought to hard sell 'Large Taxpayer Units', as promised in the the Budget.

They said these units would provide a single window system for large taxpayers to pay up Income Tax, Service Tax, Customs and excise duties and would be beneficial for India Inc since it would do away with many hurdles at one go.

Shome pointed out that large taxpayers units exist in about 50 countries.