The NFL is making a rule change and now you'll see different coaches throwing the red challenge flag on the sidelines. The NFL is making a change to the challenge flag rule that will go into effect for the 2026 season. This rule change may seem like a small tweak, but it will take some responsibility off the head coach's plate and put more pressure on an assistant. “Traditionally, head coaches have been the only member of a team that can declare a challenge by throwing the red flag. The rule only allows a team to designate another member of the coaching staff to throw the challenge flag.