I have a Navigo monthly pass, valid for zones 1 to 3. When I try to buy a 'complement de parcours' to Aeroport CDG from Arcueil-Cachan, it shows me the price to be something between 7€ and 8€. From Gare du Nord, it shows me the price to be 5.70€. Why the difference, given that both Gare du Nord and Arcueil-Cachan are in zones 1 to 3?

As per http://www.ratp.fr/fr/ratp/r_84551/complement-de-parcours/ the correct price in both cases should be the fare from Le Blanc Mesnil to Aeroport CDG, which is indeed 5.70€.

  • It's a new feature (jan 2013), maybe it's a bug, ask ratp and bring us their answer.
    – travelot
    Commented Apr 3, 2013 at 13:49
  • 1
    I asked RATP information agents at Arcueil-Cachan and Châtelet-Les Halles. They didn't even understand or acknowledge the existence of a bug. Instead they offered suggestions like "buy it at Paris" or "buy it at Blanc-Mesnil", which defeat the purpose of a complement de parcours entirely. I asked SNCF agents at Gare du Nord too, they were marginally better but offered similar suggestions. I'll try again at an RATP agence commerciale, perhaps they will have more competent staff.
    – Prateek
    Commented Apr 7, 2013 at 14:14

2 Answers 2


I think it's a bug. After doing a bit of experimenting and digging around, it seems that the price of a complément de parcours varies depending on whether you buy it from RATP or SNCF. (RATP runs the metro, buses, trams except T4, most of RER A and RER B south of Paris; SNCF runs all other suburban trains.) SNCF charges the expected price, while RATP charges more for some unknown reason.

In my experience, and yours, and other people's, SNCF charges the expected price: 5.70€ for a complément de parcous for a trip from zones 1–3 to Roissy CDG airport. This is the price of a ticket from Le Blanc-Mesnil (last station in zone 3) to CDG. I can confirm that this is the price whether buying the complément from CDG (which is an SNCF-only station) or from Paris at an SNCF ticket vending machine.

RATP charges more: 7.05€ (confirmed from several different metro stations). I have no idea where this price comes from. I found an official answer on a forum, stating that “the difference in price between [the] outward journey and the return journey is due to the airport tax”, but it makes no sense: the airport tax applies to both companies and in both directions.

As of Feburary 2015, the RATP pricing bug has been fixed. The price of a complément de parcours between zone 3 and Roissy CDG is now 6€ (which is consistent with the pricing rules) whether you buy it from RATP or SNCF.

  • Thanks, it's good to see that others have reported it too. Unfortunately the staff are unable to explain the situation (or in many cases, even understand it) satisfactorily. Here's a relevant tweet from the official RER B account : twitter.com/RERB/status/378467944780410881
    – Prateek
    Commented Oct 10, 2013 at 12:33

I think it's a bug. I suspect that the bug arises from the fact that Arcueil is a zone 3 station, and it is possible that the vending machine is not correctly integrating the fact that you already have a “zones 1-3” pass into the equation.

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    Indeed, it seems to be a bug, but not related to starting from Arcueil: I got the same price from a metro station in Paris. Apparently, SNCF charges the right price but RATP charges more! Commented Oct 2, 2013 at 21:26

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