Report showing customer discount earned for specific time frame
If you are using discount codes on sales orders, you can get this amount via the field “Amount Discount”, nested under Transaction Fields…
Create a Customer saved search with the criteria Transaction… Type = Sales Order and Transaction… Date = whatever date range you want.
Field: Name (Group)
Field: Transaction… Amount Discount (Sum)
If these customers get their discounts by a custom pricing level, (found on each line item of order) you would need to go about a different method.