Withdrawal of revaluation reserve not to be reduced from book profit if wasn't added back while crea

IT : Where revaluation reserve is created after 1-4-1997, in terms of proviso to clause (i) of second part of Explanation to section 115JB, amount withdrawn from said reserve in an assessment year commencing after 1-4-1997 would not be reduced from book profit unless book profit of such year had been increased by those reserves