Logistics Services are one of the most outsourced functions within a supply chain. This is due to easily transferrable know-how and traceable direct cost reductions, which directly impact the profit and loss statement. However, an effective management of materials and transportations on the supply and deliver side also carries indirect benefits by positively influencing the cash flow and the amount of capital locked up in inventories. Therefore, it also affects the balance sheet and the company's profitability. This paper describes an approach to make these effects transparent and traceable, by linking operational performance to the resulting changes in working capital. Having transparency on the direct and indirect effects fosters the service relationship and allows for new pricing concepts which carry advantages for both service provider and customer. The approach was developed in a collaborative action research project with a world leading provider of lead logistics services.