France administrative related

As per my experience it is totally variable and depends on the host institute. I can say this because I am in a MSCA ITN programme alongwith 15 PhD researchers, and out of this 15, three are based in France. Myself and one of my colleague are based in a company near Paris and one another colleague in based in Grenoble at the University. There are totally different contract, grant, salary and taxation system between us and the colleague in Grenoble, inspite of us being in the same country and this is totally not understanble to us. The details cannot be explianed in writing as it is quite complex but I would like to highlight that it is complex as it is different if you work in a private firm or in a public organization. The administrative stuff is totally depended upon host institution. This I can say also because of my experience with other colleagues in other countries in Europe in the same programme. Hopr this helps.