Where assessee made provision for leave encashment on actuarial basis, same being in nature of ascertained liability could not be added back for purpose of determining book profit under section 115JB. Provision for Wealth tax could not be added while computing book profit under section 115JB.  Where assessee already added provision of doubtful debts in earlier years and credited same in year under consideration, therefore, same could not be added for purpose of computing book profit under section 115JB. (AY. 2005-06 to 2007-08)