The invention relates to a method for monitoring and controlling a central IP budget of a subscriber in a packet-based communication network during online charge assessment with the monitoring a maximum limit of data transmissions. The control function is provided in a network node of the communication network, administrated by the IP centre budget allocated by a charge computer and charges the central IP budget according to the assessment charges specified said charge computer during the use of resources for transmitting several data streams in a context which can be assigned to the subscriber by the central IP budget, the level of the charge being defined by a specific datastream.