Look up your NSS with IMSS

An NSS is looked up or assigned by IMSS. It cannot reliably be determined from your name using a formula.

Official lookup or assignment

IMSS states that you can look up your NSS online using your CURP and a personal email address. Open the official IMSS service and follow its instructions.

NSS and RFC are different identifiers

The NSS is used for social security. The RFC is used for tax identification. An RFC calculator result does not reveal your NSS.

If your details do not match

Use the IMSS channels to find the appropriate correction or regularisation procedure. Do not invent a number to complete a form.