If you are traveling close to the poles and wondering when should you make the change between Magnetic Bearing or True Bearing Reference then you have come to the right place. 

Our IFD5XX/4XX Navigators will start receiving True Bearing Information at 80 Degrees North and 62 Degrees South. 

While the bearing information change will happen dynamically. The pilot will need to go into the AUX> SETUP and change the Bearing Reference to True.