A Charging Data Function (CDF) unit of an Offline Charging System (OFCS) receives Accounting Charging Request (ACR) messages from Charging Trigger Functions (CTFs). The CDF stores ACRs in designated buckets based on the source CTF and its determined status. If there is no change in the status of the source CTF, the CDF continues to store ACRs as they are received in the designated bucket. If the source CTF status has changed (i.e., a reboot or restart has occurred), the CDF allocates a new bucket for the given CTF and stores ACR messages indicating the new status in the new bucket. In addition, the receiving CDF stops storing ACR messages in the previous bucket and deprecates it as being obsolete. The CDF processes the obsolete bucket to generate incomplete Charging Data Records (CDRs) for any ACRs for which complete CDRs cannot be generated.