COFETEL type approval certificate is mandatory before selling YOUR products in mexico.
Only Mexican companies may receive COFETEL type approvals or electric safety NOM certificates.
The Mexican electric safety NOM certificate is the only legal document accepted in Mexico.

Follow up visit notification:

Mexican certification law says that all certified products are subject to additional inspection and test process during the year of validity of the certificate. It is a random process in which a certified product is chosen by the certification entity (NYCE) and the certificate holder gets notified for this follow-up visit from NYCE workers. The product can be chosen for follow up visit on the first month of validity of the certificate, or maybe on the sixth month, or even one month before the certificate expires.

When NYCE selects a certified product, they call the certificate holder to make an appointment. An employee from NYCE goes to the warehouse of the certificate holder (importer of the product) and will select one new sample of the product.

The employee from NYCE will put some special tape around the product sample box and will ask the certificate holder to send the sample to the test lab where it was first tested to obtain the current certificate.

NYCE gives 30 days to the certificate holder, so they can present the new test report. If the new test report for the sample is not presented before the 30 days, the certificate gets cancelled. Once the safety NOM certificate is cancelled, NYCE notifies the customs authorities that the product certificate has been cancelled and the product cannot be imported to Mexico anymore, until they get a new certificate going through all the process of sending a sample for testing and applying for a new certificate again.