Hello Jithin,
You have to maintain the following configuration settings in order to post the vendor clearing entry with discount.
1. Maintain Terms of Payment - OBB8 with discount parameters
2. Maintain the GL account assignment in OBXI under chart of accounts level
3.Maintain the payment terms in vendor master data with discount term
After maintaining the above data now pls go an try to post outgoing payment item for vendor.
I hope it clear else revert us with your query.
Thanks & Regards,
Lakshmi S