Communication networks and methods are disclosed for providing online charging for a session of a dual mode device that is transferred (seamless handover) from a first network domain to a second network domain. For the session involving the dual mode device, a handover application server or another network element generates a handover charging identifier that may be used in the first network domain and the second network domain. The handover application server then distributes the handover charging identifier to network elements in the second network domain and the first network domain. The network elements in the first network domain and the second network domain insert the handover charging identifier and other context information in online charging requests that are transmitted to an online charging system. The online charging system is then able to correlate online charging requests from both the first network domain and the second network domain.