IMSS stands for Instituto Mexicano del Seguro Social, or the Mexican Social Security Institute. It is the country's primary social security system, covering approximately 80 million Mexicans. All formal employers in Mexico are legally required to register their employees with IMSS and make regular contributions.
Benefits Provided
IMSS provides five categories of coverage: workplace injuries and occupational diseases, general illness and maternity, disability and life insurance, retirement and old age, and childcare and social benefits. Employees and their families receive medical care, prescriptions, hospitalization, and maternity leave through IMSS.
Employer Contribution Rates
Employer IMSS contributions typically range from 15-25% of salary depending on the employee's wage level and the company's risk classification. The contributions are calculated based on the Salario Base de Cotización (SBC), which includes base salary plus most benefits. Higher-risk industries pay more for workplace injury insurance.
EOR Relevance
An EOR in Mexico handles IMSS registration, contribution calculations, and monthly filings for all employees. This includes managing the bimonthly salary modification notices (avisos de modificación salarial) that must be filed whenever compensation changes. Non-compliance with IMSS carries significant fines and potential criminal charges.