As an Economics student I used to read that lower the Tax Rates (Income Tax) higher the collection (Of Tax).
Till now why Govt. is not following the economics rule for higher collection of Income Tax. If Govt reduce the Tax slabs I am sure Tax collection will be higher. For results Govt should wait for two year collection.
Higher Tax Rates are the reason of creation of balck money as far as my knowledge is concern. If the rates of Income Tax is 5%, 10%, and maximum should be 15% further balck money will not be created.