Fifth out of 35. That is where San Luis Potosí ranked in 2025 for permanent disabilities per 1,000 insured workers in the statistical report of the IMSS, the Mexican Social Security Institute, even though its rate of on-the-job accidents sat below the national average. For a plant manager who reports to headquarters abroad, workplace accidents in San Luis Potosí are first a question of severity, and severity is exactly what Mexico's work risk premium charges for.
How do workplace accidents in San Luis Potosí compare?
IMSS insures Mexico's private-sector employees against work risks. In 2025 it counted 15,298 work risks closed in San Luis Potosí, out of 490,070 insured workers. In IMSS terms, a work risk is an on-the-job accident, a commuting accident or an occupational disease.
| 2025 indicator | San Luis Potosí | Mexico | How to read it |
|---|---|---|---|
| Work risks per 100 workers | 3.12 | 2.92 | 7% above, pushed up by commuting and disease cases |
| On-the-job accidents per 100 | 1.82 | 1.96 | 7% below the national rate |
| Commuting accidents per 100 | 1.16 | 0.87 | 34% above; excluded from your premium |
| Occupational diseases per 10,000 | 13.9 | 9.0 | 55% above; mostly upper-limb disorders |
| Permanent disabilities per 1,000 | 3.33 | 2.10 | 58% above; fifth highest of 35 |
| Deaths per 10,000 | 0.53 | 0.49 | 9% above |
Source: IMSS, Memoria Estadística 2025, tables VII.1, VII.2, VII.3 and VII.35; cases closed during the year.
These figures are not OSHA recordable rates: IMSS counts cases closed in the year, and its total includes commuting accidents and occupational diseases. Use the table to place your site against the state, and keep your corporate incidence rate as a separate metric.
Severity per worker is where San Luis Potosí stands out
Manufacturing held 41.4% of formal employment in San Luis Potosí in December 2025, against 26.0% nationally (IMSS, Memoria Estadística 2025, table I.5). INEGI, Mexico's national statistics institute, lists 448 manufacturing plants with 51 or more employees in the state in its DENUE business directory (May 2026 cut).
Our reading, an inference from that employment mix and not an IMSS cross-tabulation, is that the state table largely describes plant floors, assembly lines and warehouses. A low accident count at your site does not protect your premium if the few cases you have are severe.
How does the IMSS premium turn severity into cost?
In Mexico each employer calculates its own work risk premium from its own closed cases, using the formula in Article 72 of the Social Security Law:
Premium = [(S/365) + V × (I + D)] × (F/N) + M
S is the number of temporary disability days paid by IMSS, I is the sum of permanent disability percentages divided by 100, D is the number of deaths, N is the average number of exposed workers and V equals 28. Temporary disability days are divided by 365, while permanent disabilities and deaths are multiplied by 28. By our own arithmetic, a single 25% permanent disability weighs as much as 2,555 days of temporary disability (28 × 0.25 × 365).
The calendar matters for a foreign headquarters. The premium is declared in February and applies from March through the following February, under article 32 of the RACERF, the IMSS regulation on employer classification and contributions. It is charged on the contribution-base wages of the whole payroll and can move up or down by at most one percentage point per year (Social Security Law, article 74), so one severe case can use up the full allowed increase. For budgeting, treat each permanent disability as a line item that reaches next year's payroll cost. Sites with a safety management system accredited by the STPS, Mexico's federal labor ministry, use a premium factor F of 2.2 instead of 2.3. Our guide to the IMSS work risk premium walks through the full calculation.
Why commuting accidents stay out of your premium
Article 42 of the Social Security Law treats an accident on the direct trip between home and work as a work accident, so the employee gets full IMSS coverage. Article 72 then excludes those commuting accidents from the employer's claims experience for premium purposes. San Luis Potosí recorded 1.16 commuting accidents per 100 workers in 2025, 34% above the national 0.87 (IMSS, Memoria Estadística 2025).
That leaves two tasks for the site. Check that no commuting case slipped into the February declaration, since it would raise a premium the law does not charge for it. Commuting injuries still empty a workstation, even when they cost nothing in premium. Personnel transport and shift-change timing are fair agenda items for the joint safety and health commission (comisión de seguridad e higiene).
Upper-limb disorders dominate occupational disease
Of the 683 occupational diseases IMSS recorded in San Luis Potosí in 2025, 480 (70%) were shoulder injuries, carpal tunnel syndrome and tenosynovitis, and 70% of the cases involved women (Memoria Estadística 2025, table VII.27). The state rate of 13.9 per 10,000 workers is 55% above the national 9.0.
These are repetitive-strain conditions typical of assembly work. For an assembly plant in San Luis Potosí, ergonomics is the prevention lever with the strongest local evidence. The relevant Mexican Official Standard (NOM) is NOM-036-1-STPS-2018 on ergonomic risk factors, and periodic medical surveillance through an occupational health program can catch cases at an early stage.
Almost half of work risks hit first-year workers
Nationally, 48.2% of workplace accidents and occupational diseases happen to people with less than one year in their position (IMSS, Memoria Estadística 2025, table VII.12). The table is national, not state-level, and it applies to any plant hiring in volume for a launch.
Onboarding is the control that reaches that group: a pre-employment medical exam, start-up training on the equipment the person will run with a DC-3 (Mexico's official record of job skills training under Article 153-V of the Federal Labor Law), and close supervision in the first weeks. Start-up courses are listed under DC-3 safety training in San Luis Potosí.
A pre-February checklist for San Luis Potosí plants
The annual premium declaration is due in February (RACERF, article 32). Four reviews can run in the fall:
- List every permanent disability and death closed in the review period, with its percentage. These cases move the result most.
- Confirm that no commuting accident sits inside your claims experience.
- Map occupational disease cases to workstations to decide where ergonomics starts.
- Check how many injured workers had less than a year in the job and what onboarding they received.
Article 74 also refers to documented proof of preventive programs alongside closed cases when the premium is reviewed. If the review shows a pattern, STPS compliance consulting can turn it into a written program with the evidence an inspector or a corporate auditor will ask for.
Frequently asked questions
How does San Luis Potosí compare with Mexico on workplace accidents?
In 2025 San Luis Potosí had 1.82 on-the-job accidents per 100 insured workers, 7% below the national 1.96, according to the IMSS Memoria Estadística 2025. Its permanent disability rate was 3.33 per 1,000 workers, 58% above the national 2.10, and deaths were 0.53 per 10,000 against 0.49.
How much does a serious accident cost in IMSS premium?
It depends on headcount and payroll, but the Article 72 formula multiplies permanent disabilities and deaths by 28 while temporary disability days are divided by 365. One severe case can trigger the maximum increase of one percentage point at the next February declaration. That point applies to the contribution-base wages of the whole payroll for twelve months, from March to February.
How can a plant lower its IMSS work risk premium?
By reducing the claims that enter the Article 72 formula: fewer temporary disability days, fewer permanent disabilities and no deaths in the review period. The premium can drop by at most one percentage point per year under Article 74 of the Social Security Law, and sites with a safety management system accredited by the STPS use a premium factor of 2.2 instead of 2.3.
