What identification, if any, is required when two amateur radio stations end communications?

Just as it is required when beginning a contact, every amateur radio operator must transmit their own call sign when ending a communication. This serves as the official sign-off, indicating to other operators and monitoring authorities that your station has finished its transmission. The rule of thumb is consistency: you are always responsible for your own station's identification. Giving the other station's call sign as you say goodbye is polite and standard practice, but the strict legal requirement is that you transmit your own call sign before clearing the frequency.