The concept of MAT (minimum alternative tax) will become "irrelevant" as all tax exemptions given to corporates are proposed to be phased out over a period of four years, a top Finance Ministry official said.

"If all exemptions go...so MAT itself will become irrelevant. There will be no difference between book profit and profit you offer for taxation purposes," Central Board of Direct Taxes (CBDT) Chairperson Anita Kapur told reporters here.

"The Finance Minister Arun Jaitley has said that within four years, all exemptions except some which will stay like for Andhra Pradesh and Telengana, which we have given recently, will be phased out," she said. When asked about West Bengal and Bihar, she said "it's still not part of the Finance Bill.

As of now, The Finance Minister has announced in his speech, we still have to get outline of what was there for Bihar." Under current Finance Bill, she said, "We have only done for Andhra Pradesh and Telengana. But in my view, once the exemption are gone, there is also need to be a call taken that there are some exemptions with sunset...so the Minister also needs to look at those which are going to be sunset, from which date they will sunset, whether the units continued to enjoy benefits."

During the course of the year, she said, "the Finance Minister will come out with the roadmap for which are the exemptions, when they are setting...it is a process, we have enough time to come out.

We hope to bring out a roadmap for what we want to do". In the Budget speech Jaitley proposed to bring down basic rate of Corporate Tax to 25 per cent from 30 per cent in the next four years.

"This process of reduction has to be necessarily accompanied by rationalisation and removal of various kinds of tax exemptions and incentives for corporate taxpayers, which incidentally account for a large number of tax disputes," he had said.

The Minimum Alternative Tax was originally brought into play to bring into the tax net large domestic corporate who did not pay taxes by making use of various incentive schemes.

The tax authorities had recently sent communications under the provision to foreign portfolio investors, asking them to explain why the provision should not apply to them. The current rate of MAT is 20 percent.