Dear Prathit,
For the invoices raised up to 28th February 2015, the time limit of six months will apply. For invoices raised on or after 1st March 2015, the time limit of one year will apply.
As pointed out by Mr. Prathasarathy, the said limit is for taking the credit and not for utilizing the same. i.e. the credit needs to be reflected in the return within the above time limits. Once the credit has been taken, then there is no time limit for utilizing the same to discharge liability of excise / service tax.
Further regarding the restriction on utilization of cess. In case the output liability is of excise, the cenvat credit of cess on inputs and input services received prior to 01st March 2015 (and not 31st March 2015) and pending to be utilized as on 1st March 2015 cannot be utilized as there will be no output liability of cess post 1st March 2015.
In case the output liability is of service tax, then cess is applicable up to 31st May 2015. Hence credit of cess will be capable of being utilized till this date, post which the credit cannot be utilized as there will be no output liability of cess.
Cess charged on inputs/ input services received post 1st March 2015 (in case of manufacturers) is eligible as per notification no 12/2015 - CE.
Also note that in case there is credit of cess pending to be utilized as on the above mentioned dates, then you may avail the same by reflecting in the returns and carry forward the same. In case there is any old matter wherein demand gets raised on assessment / audit or any other reason, then you may be able to utilize the balance credit, subject to fulfilment of all other conditions.
Thanks & Regards
CA Yash Goyal