What Happens If a Company Does Not Register Its Employees with the IMSS? (2026 Guide)
Failing to register employees with the IMSS (Mexican Social Security Institute) is one of the most serious labor and fiscal violations a company can commit in Mexico. Beyond being illegal, it exposes employers to significant fines, back payments, legal liabilities, and even criminal consequences, especially after Mexico’s labor reforms and stricter enforcement in recent years.
This guide explains everything companies need to know in 2025: legal risks, financial consequences, employee rights, how inspections work, and how to correct non-compliance.
1. Is It Mandatory to Register Employees with the IMSS?
Yes.
Under Mexican law, every employer must register each employee with the IMSS from day one of the employment relationship.
Mandatory obligations include:
- Register the employee in the IMSS system
- Report the correct salary (SBC – Salario Base de Cotización)
- Pay employer/employee contributions
- Keep payroll and employment documentation updated
Failure to do so equals social security evasion.
2. Consequences for Not Registering Employees with the IMSS
Mexico imposes multiple layers of penalties—financial, civil, labor-related, and in severe cases, criminal.
2.1. IMSS Fines and Penalties
If the IMSS discovers unregistered workers, the employer must pay:
✔ Up to 350% surcharge on contributions not paid
IMSS calculates what should have been paid since the employee’s first working day and adds:
- Surcharges
- Late fees
- Updated inflation adjustments
- Fines for omission
This can easily equal months or years of payroll contributions at once.
2.2. Payment of Retroactive Social Security Contributions
Employers must cover:
- Health insurance
- Occupational risk insurance
- Disability and life insurance
- Retirement contributions
- Infonavit (housing) contributions
- State payroll contributions (ISR payroll implications as well)
This debt can be extremely large for companies with many workers or long periods of omission.
2.3. Labor Lawsuits and Employee Claims
Employees NOT registered with IMSS gain the right to sue for:
- Full retroactive social security registration
- Payment of all benefits not granted
- Compensation for workplace accidents
- Damages for lack of medical coverage
Courts almost always rule against the employer in these cases.
2.4. Employer Liability for Workplace Accidents
If an unregistered employee suffers a workplace injury:
The employer must pay everything out of pocket:
- Medical treatment
- Surgeries
- Medications
- Permanent disability payments
- Wage replacement
- Rehabilitation
- Death benefits for the family
Even a single accident can financially devastate a company.
2.5. Criminal Liability (In Severe or Repeated Cases)
Under recent reforms, systematically avoiding IMSS registration can be considered:
Tax evasion or social security fraud
This may lead to:
- Criminal investigations
- Asset freezes
- Prosecution of executives
- Closure of operations
This is rare, but it does happen when intentional evasion is detected.
3. How IMSS Detects Unregistered Employees
IMSS performs constant monitoring using several mechanisms:
✔ Surprise workplace inspections
Inspectors may request employee lists, payroll documents, and proof of registration.
✔ Cross-checking SAT data
IMSS compares SAT (tax authority) data with payroll CFDIs.
✔ Employee reports
Workers can anonymously report employers.
✔ Digital algorithms
Risk-based models flag companies with suspicious payroll patterns.
✔ Infonavit & Labor Ministry coordination
Agencies share information on wages, contracts, and social security.
In 2025, enforcement is much stricter due to federal digitalization.
4. Risks for Employees If Not Registered
Unregistered workers lose:
- IMSS medical coverage
- Maternity/paternity support
- Occupational risk insurance
- Disability benefits
- Childcare (Guarderías del IMSS)
- Retirement funds
- Housing credits through Infonavit
In other words, lack of registration severely harms the employee’s future.
5. How to Fix Non-Compliance (Correcting the Problem)
Companies can take immediate steps to regularize:
Step 1: Register the employee in the IMSS portal
Via IMSS-Digital or the SUA system.
Step 2: Adjust payroll and SBC correctly
Avoid under-declaring salaries (another common violation).
Step 3: Pay retroactive social security contributions
IMSS will calculate missing payments.
Step 4: Update employment contracts and files
Correct personal data, job roles, and salary structures.
Step 5: Train internal HR/payroll teams
To prevent repeated errors.
Step 6: Consider outsourcing through a compliant EOR or payroll provider
This eliminates the risk of mismanagement.
6. How to Avoid IMSS Problems in the Future
✔ Ensure every employee is registered on day one
✔ Use correct SBC salary calculations
✔ Keep payroll documentation aligned with SAT and IMSS
✔ Conduct internal audits every quarter
✔ Avoid “under-the-table” payments
✔ Use specialized labor and payroll advisors
Compliance is always cheaper than the penalties.
Conclusion
Not registering employees with IMSS in Mexico is illegal, expensive, and dangerous for companies.
The consequences include:
- Large retroactive debts
- Severe fines
- Labor lawsuits
- Accident liabilities
- Possible criminal exposure
In 2025, with digital enforcement and cross-agency coordination, it is easier than ever for IMSS to detect non-compliance.
Registering employees correctly is not only a legal obligation — it protects the company, its workforce, and operational continuity.
