Incapacidad IMSS: How Mexico Sick Leave Pay Works for Illness, Maternity, and Work Risk

When a worker in Mexico is signed off with an incapacidad IMSS (a temporary-incapacity certificate), the employer normally stops paying salary for those days, and the Instituto Mexicano del Seguro Social (IMSS, the public social-security institute) pays the worker a cash subsidy instead. Mexico sick leave pay depends on the certificate type: 60% of the contribution wage from the fourth day for general illness, 100% for 84 days of maternity, and 100% from the first day for a work accident or occupational disease. For every certificate, payroll has to stop the salary, record the days, and change which contributions are owed.

Who pays during an incapacidad IMSS

The Ley Federal del Trabajo (LFT, the Federal Labor Law) treats a temporary incapacity from a non-work illness or accident as a suspension of the duty to work and to pay salary (LFT Art. 42-II). For work accidents and occupational diseases, an employer that has registered its workers with the IMSS is relieved of the LFT's work-risk liabilities (Ley del Seguro Social, LSS Art. 53).

The employer owes no salary for the certificate days unless the employment contract, an internal policy (a voluntary company rule), or a collective bargaining agreement promises a top-up. Common top-ups pay the three unsubsidized days of general illness, or the gap between the general-illness subsidy (60% of the SBC) and full salary.

Every subsidy is calculated on the Salario Base de Cotización (SBC, the integrated daily contribution wage registered with the IMSS, including benefits such as the aguinaldo year-end bonus and the vacation premium). The SBC is capped at 25 times the UMA (Unidad de Medida y Actualización, the reference unit for social-security limits; LSS Art. 28). With the 2026 UMA at MXN$117.31 a day, effective 1 February 2026, the cap is MXN$2,932.75 a day.

General illness: 60% of the SBC from day 4

For an illness or accident unrelated to work (incapacidad por enfermedad general), the IMSS pays a subsidy from the fourth day, for up to 52 weeks, extendable by up to 26 more weeks after an IMSS medical review (LSS Art. 96). The subsidy is 60% of the worker's last daily SBC, paid weekly in arrears directly to the worker (LSS Art. 98).

To qualify, a permanent worker needs at least four weekly contributions immediately before the illness; a temporary worker needs six weekly contributions in the previous four months (LSS Art. 97).

Maternity: 84 days at 100%, if the worker has 30 contribution weeks

Mexico maternity leave pay is the IMSS maternity subsidy (incapacidad por maternidad): 100% of the worker's last daily SBC for 42 days before and 42 days after the birth, 84 days in total (LSS Art. 101). The worker can ask to move up to four of the six prenatal weeks to after the birth, with written authorization from the IMSS doctor or her external prenatal doctor (LSS Art. 102 Bis); the subsidy still covers 84 days. Since a 2023 amendment, the worker can also ask for a single 84-day certificate issued at the start of the leave.

The worker needs at least 30 weekly contributions in the 12 months before the subsidy starts (LSS Art. 102-I). Without those 30 weeks, the IMSS pays nothing and the employer owes her full salary for the whole leave (LSS Art. 103). Article 103 also releases the employer only "up to the limits established by this Law". Mexican accounting and tax commentators read that wording to mean the employer owes the gap between full salary and the capped subsidy for a worker paid above the 25 UMA cap. Their basis is the Constitution (Art. 123-A-V) and LFT Art. 170-V, which guarantee full salary during maternity leave.

Work risk: 100% from day 1

For a work risk (riesgo de trabajo: a work accident, commuting accident, or occupational disease), the IMSS subsidy is 100% of the SBC registered when the risk occurred. The IMSS pays the subsidy from the first day until it declares the worker fit or rates a permanent incapacity (LSS Art. 58-I). No minimum contribution weeks apply.

If a work injury is certified as general illness, the worker loses the subsidy for days 1 to 3 and receives 60% instead of 100% after that. The misclassified days are also missing from the subsidized work-risk days in the employer's annual Riesgos de Trabajo filing (the yearly declaration that resets the employer's work-risk premium rate).

Certificate folios, online lookup, and how payroll records the days

The IMSS doctor issues a certificado de incapacidad temporal para el trabajo, identified by a folio (a unique reference number). Through the IMSS online services, employers can look up each worker's certificates and see the folio, the insurance branch (ramo), the start and end dates, and the days authorized. An employer with a convenio de pago indirecto y reembolso de subsidios (an IMSS reimbursement agreement) pays the subsidy through its own payroll and is reimbursed by the IMSS.

Payroll captures the folio in the SUA (Sistema Único de Autodeterminación, the IMSS contribution software), which excludes the certificate days from the contribution calculation. On the CFDI de nómina (the electronic payslip filed with the SAT, the tax authority), the Incapacidades section records the type, days, and amount. Type codes follow the SAT catalog c_TipoIncapacidad: 01 work risk, 02 general illness, 03 maternity, and 04 leave to care for a child with cancer. The section is required whenever the payslip shows deduction code 006 (descuento por incapacidad) or earnings code 014 (subsidios por incapacidad).

The subsidy is exempt from income tax (Ley del ISR Art. 93-VIII). An employer top-up can also qualify as exempt previsión social (employee welfare benefits) when granted on a general basis under the law or the employment contract, within the Article 93 limits; otherwise the top-up is taxed as wages.

IMSS and INFONAVIT contributions during an incapacidad

For days covered by an IMSS certificate, no IMSS contribution is owed except Retiro, the 2% employer-only retirement contribution on the SBC (LSS Art. 31-IV). Cesantía en Edad Avanzada y Vejez (old-age and late-career unemployment insurance) is not owed either.

INFONAVIT (the national workers' housing fund) is different: the employer's 5% housing contribution is still owed during an IMSS incapacidad, a rule in Ley del INFONAVIT Art. 29 since 1997. A reform published on 21 February 2025 added that a worker's INFONAVIT loan deductions (mortgage repayments withheld from salary) are no longer suspended during absences or incapacidades. INFONAVIT's Criterio 01/2025 adds that the employer never deducts more than the salary actually paid and owes nothing for the amount it could not deduct.

The 2025 reform is contested: in Contradicción de Criterios 120/2025 (4 November 2025; jurisprudencia P./J. 6/2025 (12a.)), the Supreme Court held that employers challenging it through an amparo (a constitutional lawsuit) can obtain a provisional suspension (a temporary order pausing the deduction obligation) after guaranteeing the amount. The Court did not rule on whether the reform is constitutional, so loan deductions during an incapacidad are a point to confirm for each client.

A 10-day general-illness incapacidad, worked through

Take a worker paid MXN$500 a day with an SBC of MXN$525. She receives a 10-day general-illness certificate, type 02.

• Days 1 to 3: no subsidy and no salary, MXN$1,500 less than her normal pay.
• Days 4 to 10: the IMSS pays 7 days × 60% × MXN$525 = 7 × MXN$315 = MXN$2,205.
• Payroll: the employer pays no salary for the 10 days (normally 10 × MXN$500 = MXN$5,000). Her income is MXN$2,205 instead of MXN$5,000, a gap of MXN$2,795.
• Optional top-up: a policy that guarantees full pay would pay MXN$2,795 through payroll as earnings code 014, with the Incapacidades section showing type 02 and 10 days.
• Contributions for the 10 days: Retiro at 2% × MXN$525 × 10 = MXN$105, plus INFONAVIT at 5% × MXN$525 × 10 = MXN$262.50, both paid by the employer.

Summary

An incapacidad IMSS suspends the employer's duty to pay salary, and the IMSS pays a subsidy instead: 60% of the last daily SBC from day 4 for general illness, 100% for 84 days of maternity (30 contribution weeks required), and 100% from day 1 for work risk. For certificate days, only Retiro and the 5% INFONAVIT contribution are owed. Payroll records each certificate by folio in the SUA and by type and days in the CFDI.

One certificate changes the salary, the contributions, and the CFDI at once, and a manual spreadsheet can miss one of the three. Flux is built to apply all three changes in the same pay run.