10 September 2010
See the provision is very clear :
"Notwithstanding anything contained in any other provision of this Act, where in the case of an assessee, being a company, the income-tax, payable on the total income as computed under this Act in respect of any previous year relevant to the assessment year commencing on or after 84a[the 1st day of April, 85[86[2010]]], is less than 86a[87[88[fifteen per cent]]] of its book profit, 89[such book profit shall be deemed to be the total income of the assessee and the tax payable by the assessee on such total income shall be the amount of income-tax at the rate of 86a[87[88[fifteen per cent]]].]"
So when the normal Tax is lesser than Tax under section 115JB, then only this MAT applies.