Provissional assessment ( rule 7 )

Sir, We have workedout diff duty along with interest on 01.09.2012 and discharged diff duty on same day. Interest was not paid because my boss is saying present we dont have PLA balance and same thing there is no provision to pay interest on delay payment of interest. His view is correct or not ? pls provide reference. Tnaks in advance.........

on paying the final duty, the assesee has to issue suplimentary invoice, and the date of last invoice will be considered for final (difference in duty) amount. 

sir, thanks you, Is there any provision to pay interest on delay payment of interest ? For example Due date of payment of excise duty is 6th every month. My Liability is 100000, if i pay the duty on 10th i should pay along with interest. I calculated interest on 1 lack on 10th i.e 1000 (assume) i paid 1 lack on 10th i paid 1000 interest on 20th. The total duty discharged on 10th only but interest paid in delay. Pls suggest me... Is there any any provision to pay interest on delay payment of interest ?

not needed to go such indepth, 

pay both and file return, if department will find it inappropriate, then they will ask you for the diff, as in corporates the person incharge calculate upto the date but the cheque is issued few days later, again challan deposited few days later, so its not possible to take always "few days later provision" in hand, so better you file the return and let department ask for the diff, as it would be fixed and would allow you some week time to pay the same.