Systems and methods that handle failover between peer charging functions for offline charging. In one embodiment, a Charging Trigger Function (CTF) of a network element detects an interim chargeable event during a session, and generates an interim accounting request for the session responsive to the interim chargeable event. The CTF inserts a session anchor timestamp in the interim accounting request indicating the start time for the session, and transmits the interim accounting request to a charging function. The charging function then monitors a time limit trigger for closing a Charging Data Record (CDR) for the session based on the session anchor timestamp.