Why do I need to add all trains to my Interrail Pass if I already have seat reservations?

The Interrail Pass and seat reservations can be seen as two components that depend on each other to function. The Interrail Pass is your travel ticket that allows you to travel by train. The seat reservation is your seat ticket and guarantees you a seat on the train.

When you purchase your seat reservations, you will receive the tickets as e-tickets or paper tickets. You must still add all the routes you will travel in the app to generate a travel ticket with a QR code. It is crucial to add all trips to the app, not only to ensure you have a valid ticket but also to correctly count the number of travel days and in/outbound trips so that the pass is used correctly.