Social Security health reimbursements are calculated on the basis of a basic rate, known as the "convention rate", set by various players in the health world (health professionals, health insurance, the State). 

The Health Insurance applies a reimbursement rate to this basic tariff. This rate varies according to the nature of the medical service or compliance with the coordinated care pathway. 

For example, when you go to see your general practitioner for a simple consultation, if you have declared him or her as your treating physician, Social Security will reimburse 70% of the amount of this consultation, and between 15% and 70% of the amount of the medication prescribed. 

In the end, Social Security does not reimburse all of your medical expenses and you may still have to pay part of them, such as : 

The co-payment is the remaining part between the Social Security reimbursement and the convention fee), the remaining 30% compared to the cost of the consultation in the previous example. 

Overruns, for example if the doctor you consult charges more than the agreed fees (link to "Sector 1, 2, 3: what are the differences"). 

Medical deductibles are lump sums deducted from Social Security reimbursements (fixed by decree: for example: 1€ for consultations with general practitioners; 0.50€ for paramedical acts and medicines; 2€ for transport, etc.). 

If you benefit from the Alsace Moselle regime in force in 3 departments (57, 67 and 68), social security reimburses you on average at a rate of 90%. 

In some cases, the expenses that remain at your expense can be very high: dentures, hospitalization, etc ... And the use of a mutual insurance company is essential !