The OASI (German: AHV; French/Italian. AVS) number is a number assigned to all persons living or working in Switzerland: it is the social insurance number (this webpage of the Federal Social Insurance Office is available in German, French and Italian), which is also used for other administrative purposes.
The OASI number is made up of 13 digits. It is anonymous and cannot be reconstructed or traced back to a person in any way
You are assigned an OASI number regardless of whether you are a Swiss citizen or a foreign national. Cross-border workers are also given an OASI number. You can find your OASI number on your Swiss health insurance card or by contacting your Swiss health insurance provider. If you are an employee, you can also ask your employer for your OASI number. If you are self-employed, you can also ask your social insurance office (professional fund association or your cantonal OASI office).
Every child living in Switzerland is given an OASI number as soon as soon as the child’s parents register him or her for health insurance. This must be done within three months of the child’s birth or within three months of the family’s arrival in Switzerland. You can find your children’s OASI numbers on their health insurance cards or by contacting their health insurance provider.