The discount_allocation object
The discount_allocation object contains all of the information about how a particular discount affects a line item and how the price reduces. The object can be accessed on customer order and notification templates. Shopify Plus merchants can also access properties of the discount_allocation object in the checkout.liquid layout file.
The discount_allocation object has the following attributes:
discount_allocation.amount
The discounted amount on a line item by a particular discount.
discount_allocation.discount_application
The discount application that allocates the amount on the line item.