I have removed goods on 05.01.2012 @10% of excise duty and regularly supply the product as per the PO. I have also asked my customer for upward revision of rates. on 20.04.2012 my customer has revised the same with retrospective effect from Jan 2012.
Let me know if I have to raise the supplementary bill for the removals up to 17.03.2012 what rate i have to charge- a) Rate at the time of removal ie 10% or b) Rate at the time of supplementary Invoice ie 12%