If you seek medical treatment in France you will need to pay at the end of each consultation/hospitalisation and later receive reimbursement from the social security system (as well as your voluntary insurer if you have one).
Historically, in order to obtain reimbursement in the French health system it was necessary to submit a receipt for the treatment (feuille de soins) to your local Caisse d'Assurance Maladie. This is still the case with some medical professionals and chemists who have not moved on to the new system.
In recent years the paper based process has been streamlined and automated with the issue to everyone of a plastic health insurance card. The card is embedded with a microchip and contains your social security insurance details. It does not include medical information, although some pilot studies are being undertaken with such cards. Since 2008 the cards have photo identity on them.
The card is called a Carte Vitale.
Everyone aged 16+ years of age is required to have one. Children under 16 years are included on the card of their parent or guardian.
The card is presented to your French doctor who places it into a card reader enabling you to later obtain direct reimbursement from the insurance fund, rather than having to submit a feuille de soins. The card itself is not a means of payment, but a means of easier reimbursement.
You can also normally use it in your local chemist.
If you have voluntary insurance, the system will also (normally) pay directly into your bank account that part of the charge that is not fully reimbursable from the social security system, subject to the conditions of cover.
So make sure you bring it with you when you seek medical treatment and it is always a good idea to carry it around with you.
You should normally expect to receive reimbursement directly into your bank account within a week.
Where there are excess medical charges (called dépassements) over the official tariffs you may be able to get reimbursement from your voluntary insurer. If not, the costs fall to you.
Until you are fully installed in the French health system you will need to use the feuille de soins, as you will not be provided with a carte vitale.
The process of issue of the carte vitale normally takes a few weeks, but can sometime drag on due to local ineffeciencies or work pressures.