It turns the RER from an expensive nuisance into a free library, mobile office, and people-watching lounge that happens to move.
Unlike the monthly Navigo, which you have to manually buy every 30 days, the Annuel is a direct debit. They take the money automatically on the 5th of each month. Here is the headline stat: You get 1 month free per year. souscrire navigo annuel
Since the Annuel costs €950.40, your employer will pay roughly back to you over the year. It turns the RER from an expensive nuisance