Discount on VAT purchase

Pradeep Jain (service) (143 Points)

12 June 2009  

Our supplier is making us invoice in the following format
Gross Amt.          100
Vat                            4
Total                    104
Discount                 4
Net Invoice Amt.  100

Now please suggest me whether at the time of booking of invoice, we should change vat amount in proportion of discount amount also as discount is given on total amount inclusive of VAT.