In the ConnectWise PSA, the Less Included setting calculates the total amount of usage for each addition based on usage then subtracts the amount in the Less Included field. When the usage exceeds the quoted amount, the Addition will calculate the incremental amount and add it to the invoice. If the usage falls below the quoted amount the Addition adds $0 to the revenue. The Base Charge is unchanged and represents the minimum charge for usage based Additions on the quote.

MSPCFO accounts for the cost of the less included by calculating the total less included units times unit cost and adding the total cost  in a cost override on the top line of the agreement. The following is a video that explains the process in MSPCFO: