Recent studies on handover communication highlight the role of the incoming physician in preventing misunderstandings that contribute to medical errors. However, existing research often only provides abstract recommendations for increasing their participation, without specifying where and how this should occur. This paper applies discourse theory and methods to identify where the incoming physician's active involvement is interactionally appropriate and can be integrated naturally and effectively. Twelve handovers between six pairs of resident physicians were recorded in a simulated ICU setting at a teaching hospital and analyzed using a combination of genre theory and conversation analysis. By first identifying the "moves" that constitute the handover genre, we pinpointed places where active participation by the incoming physician is expected and facilitates effective communication. While the "tasks and focus points" and the "questions and consultation" moves clearly invite such participation, the "clinical situation" move requires more negotiation, as the outgoing physician maintains control over the conversational floor, making it less immediately accessible for the incoming physician to contribute. The four remaining moves exhibit a more monologic pattern, where both participants display interactional behavior signaling that active input from the incoming physician is not anticipated. Our findings suggest that medical professionals share an implicit understanding of when participation is appropriate, shaped by conventions of the handover genre itself. By reconstructing these tacit rules through genre theory and conversation analysis, we provide insights that can inform training methods, ensuring that recommendations for active participation by the incoming physician align with the structured expectations of clinical practice.