Our customers require to be able a minimum turnover amount on a customer group level that must be reached to achieve rebates.
The rebate functionality allows to define a "From amount", but this is only valid for one single customer.
Furthermore the rebate functionality allows to set the payment type to "Invoice customer deductions", but this parameter only defines the account that receives the credit.

It is required to define a "From amount" related to the invoice account (all customers belonging to this account) or related to the customer rebate group.