11 September 2014
You need to follow following steps :
1. You calculate again the net tax payable by your client on the his total Income.
2. Also Add intrest accordingly if notice period is expired.
3. Submit these details by Post to AO along with Form -16 , challan of advance tax etc. if any deposited.
4. If time to intimation lapsed then it is also suggested to meet AO along with the details mentioned above.
AO will determine 12-13 IT return as per your calculations over and above their assessed value before sending final refund or demand notice against your claimed refund.
The FY 13-14 IT return will be determined separately . It is likely that AO may send you final refund after determining all dues of FY 12-13 with FY 13-14 refund .