Salesforce CPQ Discount Schedule Selecting Higher Tier than Expected on Net New Amendment Quote Line

This behavior is due to the Discount Schedule having an Aggregation Scope of "Quote" and a Quote Line Quantity Field set to "Quantity".

On the amendment quote, the discount schedule is aggregating Quantity of the product for the entire quote -- this includes the "existing" quantity from the existing line plus the net-new quantity from the new line.

This is the expected behavior of discount schedules. It may be possible to achieve alternative behavior by modifying the discount schedule or changing business process. Please note that these recommendations are generalized recommendations based on native CPQ capabilities:

1. Perform an add-on instead of an amendment. Add-ons are a way to add a net-new quote to an existing contract by processing a net-new Opportunity and Quote. The dates will need to be properly aligned to the contract to ensure the add-on goes into effect at the desired time. The discount schedule will not need to be changed, but there will need to be a business process change to use add-ons instead of amendments for these situations.

2. Change the Aggregation Scope to "--None--". This will cause CPQ to evaluate each quote line quantity individually when evaluating discount tier. Note that any use cases that hinge on multiple lines of the same product on a quote aggregating their total quantity to determine discount tier will no longer evaluate the total quantity and will only evaluate each line's individual quantity for discount tier determination.

3. Change the Quote Line Quantity Field of the discount schedule to reference Effective Quantity instead of Quantity. Since the effective quantity of existing lines on amendment is 0, CPQ will only evaluate discount tier based on the net new lines. Please note that the Effective Quantity field is also used in tandem with other CPQ functionalities such as Block Pricing. Note that Block-priced quote lines have an Effective Quantity of 1; they will not receive any discount past the quantity 1 tier regardless of the value in the quantity field. Additionally, this will not function as desired if, on amendment, the existing quote line has it's quantity increased.