My son and I will be in Paris in May, and I plan to buy a Navigo Decouverte pass for Zones 1-2, since we will probably not leave Zone 2 while we're there. We'll be starting at CDG, though, and the online calculator says it'll cost 9.75 Euros to take the RER B and Metro to our apartment.
But the tariff page says there is something called the Complement de Parcours that lets you save money on RATP fares outside of your Navigo zone:
Does the Navigo Decouverte qualify for this discount? Or is it only the Navigo Mois et Semaine, for French inhabitants?
If it qualifies, then I'll go to the effort of buying our Navigo passes at the airport. If not, I'll just get them in town. Thanks!