S. 40(a)(ia): Amounts not deductible – Failure to deduct tax at source – Payment exceeding Rs. 20,000 to each truck owners – Contract with a cement factory for transporting cement – Payment made to truck operator/owner amounts to payment made to a sub-contractor – Disallowance is not limited only to amount outstanding and this provision equally applies in relation to expenses that had already been incurred and paid by assessee- S. 40(a)(ia) as introduced by Finance (No.2) Act, 2004 with effect from 01.04.2005 is applicable to and from assessment year 2005-06 – Amendment by Finance Act 2014 is prospective – Disallowance held to be justified [S. 40A(3) , 194C]