Kirti please refer to Notification No.13/2011 - CE (NT) dated 31.03.2011.
Rule 4(7) of Cenvat Credit Rules has been amended to allow credit of Service Tax on Invoices received after 31.03.2011.
In case payment on above incoives is not made within three months of date of invoice, Credit so availed will have to be paid (through PLA or CENVAT). Later when payment is made, such credit will again be available as per provisions.
In cases where Service Tax has to be paid on reverse charge basis, CENVAT Credit on cash payment basis has been continued.
Further for invoices issued before April 1, 2011, CENVAT Credit on cash payment basis has been continued.
To conclude, Notification does not speaks about provision of service and hence, wherever invoice has been received, CENVAT Credit is allowed subject to the above Notification & CENVAT Credit Rules, 2004.
Refer Link Below for above Notification:
https://www.cbec.gov.in/excise/cx-act/notfns-2k11/cx-nt2k11/cent13-2k11.htm