According to its official mission statement the French social security system (la Sécu) “gives everybody the possibility to receive health care according to his or her needs, whatever his or her income level”. What this doesn't mean is that anyone can hop off a plane from Luton, announced they've come to live in France and then claim “health care according to his or her needs”.
Nearly all legal residents of France, native or immigrant, are covered by the system. Some 85% of them qualify by being employed. When someone is hired they are declared by their employer and have to register at the nearest health insurance office (CPAM). Cover continues at retirement. There are a number of other statuses (régimes), that most likely relevant to expats is the “independent worker” (effectively self-employed). There's also special provision - CMU or couverture maladie universelle - for those on very low incomes.
Now back to that optimist who hops off the plane in Luton. Since late 2007 those who arrive in France below the age of retirement in their own country and do not work (and are thus classified as inactif) do not normally qualify for state cover until they have completed five years' residence. Such a person has to take out private insurance. After five years' residence, however, they are eligible for state cover (for example, CMU for those on low incomes). Those who arrive here as state pensioners have the same rights as French retraités.
The Sécu is generous ... however …
Two final points to note: the Sécu is generous, no doubt about it, however, it doesn't - other than in the case of certain serious illnesses or accidents (and pregnancy) - refund all medical costs. What you can get back can range from 15% for certain pharmaceuticals judged of limited value to 80% for some procedures. Remember, too, that some doctors (non-conventionnés) have chosen a status that allows them to charge fees above the standard level set by the Sécu. For those reasons most people take out top up insurance offered by a private provider (mutuelle). Again, that doesn't mean you'll get everything back. You need to choose a policy with advice from an insurance professional.
And note this, too: if you're fully covered by the French state system as a resident that doesn't mean you can hop off a plane in your own country and claim free health care - something that Brits find a surprise. As a visitor you need a European Health Insurance Card (CPAM in French) which you can pick up at your local CPAM office by showing your carte vitale, that's the little piece of green plastic issued to all assurés. Without the EHIC when seeking medical services in other EU states you'll have to pay.This is a highly simplified account of a complex system. For those with inadequate French it can be confusing - as with an elderly woman reader who panicked when she misread a letter from the CPAM and thought they were stopping her cover (we were able to put her right). Usefully, CPAM has an English-language helpline at 0811 36 36 46 which operates Monday to Friday 09h00-18h00 (local fare); there's also an English website - www.ameli.fr/l-assurance-maladie/connaitre-l-assurance-maladie/getting-informed-about-health-insurance/index.php (AMELI); this can be confusing and is occasionally linguistically rather odd (“when you visit the chemistry” ...). Anyway, here's wishing you well.