Why IMSS and SAT Compliance Is Central to REPSE
REPSE registration is not a one-time formality — it is the beginning of an ongoing compliance relationship with both Mexico's Social Security Institute (IMSS) and the Tax Administration Service (SAT). For specialized service providers, maintaining good standing with both agencies is not only a regulatory requirement but a practical necessity: your clients will routinely verify your compliance as part of their own legal obligations.
IMSS Obligations for REPSE Providers
1. Employer Registration
Before you can register in REPSE, you must already be registered as an employer with IMSS. This registration establishes your obligation to enroll your workers in the social security system and make corresponding contributions.
2. Worker Enrollment (Alta de Trabajadores)
Every worker you assign to a client's project or facility must be properly enrolled with IMSS under your employer registration number — not the client's. This is a fundamental requirement of the reform: you are the employer of record, and your workers' social security rights flow from your registration.
3. Monthly SUA Payments
IMSS contributions are calculated and paid monthly using the SUA (Sistema Único de Autodeterminación) software. Contributions cover:
- Health and maternity insurance (Enfermedad y Maternidad)
- Work risk insurance (Riesgos de Trabajo)
- Disability and life insurance (Invalidez y Vida)
- Retirement and old age (Retiro, Cesantía y Vejez — RCV)
- Day care and social benefits (Guarderías y Prestaciones Sociales)
4. Monthly Compliance Reporting to Clients
One of the most operationally demanding requirements introduced by the 2021 reform is the obligation to provide monthly compliance reports to your client companies. These reports must include:
- A list of all workers assigned to the client's project.
- Proof that IMSS contributions have been paid for those workers.
- INFONAVIT contributions, if applicable.
Clients are entitled to withhold payment if you fail to deliver this documentation on time.
5. IMSS Compliance Opinion (Opinión de Cumplimiento IMSS)
You must maintain a positive IMSS compliance opinion at all times. This document, generated through the IMSS portal, confirms you are current on all social security obligations. It is required for your initial REPSE registration and should be kept current throughout your registration period.
SAT Obligations for REPSE Providers
1. Active RFC and Tax Compliance Opinion
Your RFC (Registro Federal de Contribuyentes) must be active and in good standing with SAT. You must also maintain a positive SAT compliance opinion (Opinión de Cumplimiento SAT), which confirms you are current on federal tax obligations including income tax (ISR), VAT (IVA), and payroll tax filings.
2. CFDI Issuance for Services Rendered
All invoices issued to your client companies for specialized services must be valid CFDIs (Comprobantes Fiscales Digitales por Internet) that correctly describe the services rendered and include your REPSE folio number where required by the contract.
3. Payroll CFDI for Workers
You must issue payroll CFDIs (CFDI de Nómina) for every worker assigned to client projects. These digital payroll receipts are a core SAT requirement and serve as proof of legal employment and salary payment.
4. Information Returns
SAT requires periodic information returns that disclose the details of your service contracts with clients. This fiscal transparency requirement was a central pillar of the 2021 reform, designed to prevent tax evasion through outsourcing structures.
The INFONAVIT Factor
Beyond IMSS and SAT, REPSE providers must also stay current with INFONAVIT obligations — housing fund contributions calculated as 5% of each worker's salary. A positive INFONAVIT compliance opinion is also required for REPSE registration and renewal.
Practical Compliance Calendar
| Obligation | Frequency | Agency |
|---|---|---|
| IMSS worker contributions | Monthly | IMSS |
| Client compliance reports | Monthly | IMSS / Internal |
| Payroll CFDI issuance | Per pay period | SAT |
| IVA / ISR declarations | Monthly | SAT |
| Annual income tax return | Annually | SAT |
| INFONAVIT contributions | Bi-monthly | INFONAVIT |
| REPSE renewal | Every 3 years | STPS |
Consequences of Falling Out of Compliance
If your compliance opinions lapse or you fall behind on IMSS or SAT obligations, the consequences can cascade quickly:
- Your REPSE registration may be suspended or revoked by STPS.
- Client companies may terminate your contracts or withhold payments.
- You may face surcharges, penalties, and interest from IMSS and SAT.
- Workers' social security rights may be jeopardized, creating additional legal exposure.