Please follow the steps mentioned below to apply item level extra discount in an invoice:
Step 1: Go to Document settings
Step 2: Click on Add Custom fields
Step 3: Click on New Custom field
Step 4: Add a custom field named as Item Extra Discount(-)
Step 5: Enable Show in Totals option for the Item Extra Discount(-) field
Step 6: Click on Edit option for the Total Amount field
Step 7: Select the type as Formula >> Add the formula as Total Amount - Item Extra Discount >> Click on Save
Step 8: Click on Edit option for the Net Amount field
Step 9: Select the type as Formula >> Add the formula as Net Amount * 1 >> Click on Save
Step 10: Go to Sales dashboard >> Click on +Create Invoice
Step 11: Enter the necessary details in the invoice as shown below >> Click on Save
Now the invoice will be successfully created by applying the extra discount at item level and this extra discount will not affect the taxable amount as shown below
