Mandatory transition to the exclusive use of electronic signatures in dealings with the IMSS
Key Changes and Provisions
Exclusive use of the e.firma (SAT): The use of the Advanced Electronic Signature (e.firma) issued by the Tax Administration Service (SAT) is hereby made mandatory and exclusive for all electronic transactions with the IMSS. The use of this signature will have the same legal effect as a handwritten signature.
Abolition of the NPIE: The abolition of the use of the Employer’s Electronic Identification Number (NPIE) and the digital certificate issued by the IMSS for carrying out procedures with the IMSS has been approved.
New procedure for registering legal representatives: Where a company or employer authorises a legal representative, director or authorised agent, registration must be carried out exclusively via the IMSS Virtual Office. To do this, the representative must authenticate themselves using their own e.firma and sign jointly with the person they are representing (both using their respective e.firmas).
Timeframes and Validity
Entry into force: The provisions came into force on 17 July 2026.
Transition period: The Institute has granted a transition period of 90 calendar days, starting from 16 July 2026, to allow employers and obligated parties to complete the migration to the exclusive use of the e.firma.
Recommendations
To comply with these new obligations within the established 90-day period, we recommend that our clients:
- Check validity: Confirm that the company’s e.firma and those of all legal representatives and/or authorised agents are active and valid with the SAT.
- Update registrations: Access the IMSS Virtual Desktop to register or update the registration of authorised representatives under the new joint signature format using e.firma.
- Process transition: Stop using the NPIE or the old IMSS digital certificates in internal payroll and social security systems, ensuring that human resources and accounting staff are trained to use the new e-signature system.
At ECIJA MEXICO, we have extensive experience and are highly specialised in labour and social security matters; we are therefore at your service to assist you with this issue, which is of great importance to employers.
