<b> One can via MIRO book the discount although the PO does not have it.
On the MIRO screen enter the amount (minus the Discount + tax if applicable) in the Amount field
Enter the applicable PO number for the <i>Goods/service items </i> and select the particular PO item(s)
In addition you select the <i>G/L account </i> tab: Here you enter the G/L Account relating to discount with D/C of ‘Credit’ . enter the amount of the discount before tax with the applicable tax code (if tax is applicable).
This should do the trick and the resulting entry should post:
Goods value 100
Discount 10 %
Vat rate 14 %
Cr Vendor acc 102.6 (amount after discount (90)+ tax 14 %)
Dr GR/IR acc 100.0 (amount before discount and tax)
Cr Discount acc 10.0 (disc amount 100 * 10 %)
Dr Vat or Tax 12.6