Split ticketing to CDG on Paris's RER

Question

I will be spending a day in Paris with a friend, arriving by train into Gare du Nord in the morning, and flying out in the evening. However, my friend leaves from Charles de Gaulle, and I leave from Orly. I'd like to accompany my friend to CDG. On my return trip to Orly, I'd like to avoid Orlyval and take the scenic route via the T7 tram.

To make these two trips, it would cost €10.30 on each leg, plus €1.90 for the tram (€22.50 total). However, this doesn't afford us any additional trips during the day. A Mobilis ticket -- which would give unlimited travel but not allow travel to CDG by RER -- costs €12.40 for 4 zones. (Edit: a 4-zone Mobilis allows travel to Orly via tram T7, but not to CDG as Mobilis tickets cannot be used for airport connections -- for this reason, a 5-zone Mobilis ticket would be an extra expense for no gain).

Is it possible to use a one-way ticket from an RER station in zone 4 to CDG (or vice-versa, e.g. Parc des Expositions for €2.55 to CDG and €4.35 from) in order to supplement the Mobilis pass? Will this require exiting and re-entering the station to switch tickets (i.e. will the fare gates allow using a ticket for exit only)?

Answer 1

So, a lot of the discussion revolved around whether Mobilis zones 1-5 gives access to CDG by RER or not. There is a lot of conflicting information, to the point that you can even find a page on the Transilien website that says yes and no on the same page!

And the definitive answer is yes since January 1st, 2018. This is stated (quite indirectly and not explicitly at all) in a decision by Ile-de-France Mobilités, the authority responsible for transport in the Paris region: when they created the Navigo Jour, they aligned the validity of Mobilis with that of Navigo, so it now includes CDG by RER (and probably a few other things that weren't included either before). It still doesn't include Orlyval.

So your best option is to buy a Mobilis ticket, zones 1-5, for one day. The cost is 17.80 EUR.

As stated in Gilles' answer, you can also use a Navigo Jour, which is exactly the same thing, but loaded on a contactless Navigo pass rather than a magnetic stripe paper ticket, and requires you to buy a Navigo pass for 5 EUR (only residents of the Paris region can get it for free).

The other alternative is Paris Visite, which is more expensive, but includes discounts for some museums and monuments, and is valid on Orlyval as well. If you intend to do some sightseeing, it may be worth the extra cost.

To answer the original question (even though it now seems unnecessary), there used to be a "complément de parcours" (previously known as "prolongement de parcours"), which allowed holders of a weekly or monthly Navigo pass to go beyond their zones. This has however been replaced with the ability to buy a Navigo Jour for the relevant zones, so it no longer exists (since January 1st, 2018 as well). Not sure it would have worked to extend a Mobilis ticket anyway.

Update 28/08/2018

Got confirmation from Ile-de-France Mobilités (the organising agency for transport in the Paris region) that you can indeed use Mobilis 1-5 to access CDG by RER (but not using Orlyval or le Bus Direct for instance).

Answer 2

Split ticketing is rare in France. It is definitely not possible with a magnetic ticket such as Mobilis. You'd have to exit at Parc des Expositions (restricting you to trains that call there) and take the next train.

Navigo Jour is a day pass which is roughly equivalent to Mobilis, but Navigo is a contactless smartcard whereas Mobilis is a paper (magnetic) ticket. Navigo Jour is new since January 2018, so many information sites don't mention it. I can't even find it on the RATP website, and RATP is the agency that runs the Paris metros, many of the buses and more!

The good news about Navigo Jour is that it's explicitly valid on all public sector transportation (within the chosen zone), including RER B and Roissybus to Roissy airport and Orlybus to Orly airport. It isn't valid on the Orlyval train, however.

The bad news about Navigo Jour is that you need a Navigo pass. You can get it on the spot for 5 euros and a photo. You can't get a refund for the 5€, but you can reuse the pass if you come back in a few years. Paris itself is zone 1, Orly is in zone 4 and Roissy is in zone 5 so you'd need a zones 1–5 day pass which costs 17.80€. That's a total of 22.80€.

The Mobilis pass costs the same as the Navigo day pass, but you don't need to have anything other than the ticket itself, so it would only costs 17.80€. However I can't find a definitive source indicating whether you can use it to reach the airports via RER B, Roissybus or Orlybus. This was definitely not the case before, but the Mobilis pass rates changed in January 2018 to align it with the new Navigo Jour. The Navigo site lists only non-publicly-run transportation in its list of exclusions, so I think that Mobilis is now valid for RER B to Roissy, Roissybus and Orlybus, but I can't find a definitive official answer.

Note that if you were staying for more than one day, you could get a Navigo weekly pass for €22.80 (plus a one-time fee of €5 for the physical card). The weekly pass is valid for a calendar week (Monday to Sunday) and must be bought at the latest on Thursday.