Hello everyone,
I´m new in France and this forum. Hope I can get some help as I´ve been struggling to comprehend the processes. I have submitted the papers (permis de sejour G-frontalier) for my activity (raison individuelle) in Geneva and in order to open a Swiss bank account, the bank is asking me for my numero fiscal in France where I reside. Where do I register though to get one? I have never worked in France. I´m an EU citizen.
Thnx a lot 
Hi Kristina
If you reside in France, you will make your Income Declaration, here in France… and that will provide you with your Numero Fiscale… 
Hi Stella, thank you for the reply. So you cannot just register at the Mairie or something?
I have never worked in France and actually been living here since April this year…
If that is essential as you advised, how do I do that? To which administration office do I go? I got no clue…
Hi Kristiana…
Surely, to find your Numéro Fiscale… you must be “IN” the French system…
Le numéro fiscal figure sur les documents suivants : sur votre déclaration de revenus pré-remplie, en haut à gauche de la première page ; sur vos avis d’impôt (impôt sur le revenu, taxe d’habitation, taxe foncière) en haut à gauche, rubrique « Vos références ».
You say you’ve been living in France since April 2018 … in which case none of the above documents are yet available to you…
Perhaps you have over-complicated matters by trying to open a Bank Account in Switzerland, after moving from Geneva to France… 
Why not open an account in France ???
Thank you for your feedback, Stella.