Hi Brindha,
You will change the old rate in Table V_T510J or V_T510K table if values are there. You juse need to copy the previous recod and maintain your new rate with efective from 1st of Sept 2014. Then system automatically delimit the old record.
If value maintain in Table V_T510J then WT BHSF is calculating through valuation rule, and if it's maintained in V_T510K then there have a PCR had been written and inserted before IT14 processing function.
you can maintain these two table entry with the help of Tcode SM30.
Check and tell me.
Regards,
Sankarsan