Displaying Vendor Account Transaction (Use t-code FBL1N)
Step 1) Give Vendor account number and Company code
Select Open Items radio button
Select Normal Items check box
Execute

Step 2) Here we see the Purchase order
To view the discount in current period click change layout button
Step 3) Click the find icon
and type current
Press enter
Step 4) Select the current cash discount amount and press the left arrow button (show selected fields button)

Step 5) We now find current cash discount amount under column content
Select current cash discount
Click Copy button
Current cash discount is added to the layout
Select Open Items radio button
Select Normal Items check box
Execute
Step 2) Here we see the Purchase order
To view the discount in current period click change layout button
Step 3) Click the find icon
Press enter
Step 5) We now find current cash discount amount under column content
Select current cash discount
Click Copy button