Embodiments of the invention provide a method and device for charging of data reaching a network element of a communication network during a data session, the data session comprising a plurality of data flows, with each flow being distinguishable by a set of flow parameters. The method includes enforcing a charging policy at the network element to be applied to the data, wherein the charging policy defines charging rules per flow, observing the data reaching the network element and detecting at least one flow of data, matching the detected flow of data to an enforced charging policy, and applying the matching charging policy to the data flow, thereby generating charging information. A method and device is also provided for supplying a network element with a charging policy to be enforced at the network element for charging of data reaching the network element of a communication network during a data session.