Imss mandatory use of the e.firma for affiliation movements and employer notices

The change derives from agreement ACDO.AS2.HCT.290626/176.P.DIR, published in the Federal Official Gazette on July 16, 2026, through which the Technical Council of the Mexican Social Security Institute (IMSS) approved the exclusive use of the e.firma for acts carried out electronically. Under this measure, the e.firma issued by the Tax Administration Service (SAT) becomes the valid digital certificate for submitting affiliation movements and other electronic employer procedures.

Scope of the change

The e.firma will be the authentication and signature mechanism for electronic procedures before the IMSS.
The NPIE and the digital certificate issued by the IMSS will no longer be used for these acts.
The linkage of legal representatives must be completed through the Virtual Desk.
The agreement establishes a transition period of 90 calendar days from its publication in the Federal Official Gazette.
Failure to update may cause delays in submitting employee registrations, terminations, and salary modifications.

Covered procedures

The provision directly affects affiliation movements submitted by employers to the IMSS, including employee registrations, terminations, and salary modifications. It also applies to notices and acts related to employer registration, the administration of legal representative powers, and access to institutional platforms such as IDSE and the Virtual Desk.

Transition period

During the 90 calendar days following publication of the agreement in the Federal Official Gazette, the previous mechanisms and the e.firma may coexist. Once this period ends, employers must operate exclusively with a valid e.firma to continue carrying out electronic procedures before the IMSS.

Operational preparation

Companies should proactively validate the validity of the e.firma of the legal entity or individual registered as the employer, as well as that of their legal representatives. For legal entities, it will be essential to confirm that the representation is properly linked in the Virtual Desk, since third-party authorization must be carried out through the joint authentication and signature of the represented party and the legal representative.

Recommended immediate actions

Verify the validity of the employer’s e.firma and that of its legal representatives.
Confirm the correct linkage of representatives in the Virtual Desk.
Review payroll and social security processes that still depend on the NPIE.
Coordinate with system providers to ensure continuity in the submission of affiliation movements.

Risks of not updating

Failure to address this change in a timely manner may result in delays in submitting salary modification notices, employee registrations, or terminations, as well as limitations in accessing the Institute’s electronic services. In practice, this could affect timely compliance with employer obligations, the correct determination of employer-employee social security contributions, and the continuity of internal payroll, social security, and compliance processes.

https://dof.gob.mx/nota_detalle.php?codigo=5793741&fecha=16/07/2026#gsc.tab=0

It is always recommended to consult a professional from ZALDIVAR CONSULTING to support proper decision-making.