ISR Withholding Certificate Mexico (Constancia de Retenciones ISR)

An ISR Withholding Certificate Mexico (Constancia de Retenciones del Impuesto sobre la Renta) is the official annual document that every employer (patrón o retenedor) is legally obligated to issue to each worker (trabajador) and to each person from whom income tax (ISR — Impuesto sobre la Renta) has been withheld during a fiscal year. The certificate summarises the total annual income (ingresos totales), total ISR withheld (ISR retenido), subsidio para el empleo paid, IMSS contributions withheld, INFONAVIT deductions, and other concepts — providing the employee with the data necessary to file their annual ISR declaration (declaración anual) before the Servicio de Administración Tributaria (SAT).

The legal obligation to issue the constancia de retenciones is established in Article 99 Fraction III of the Ley del Impuesto sobre la Renta (LISR), which states that employers must deliver to each worker no later than 15 February of each year a written certificate of the total wages paid and the total ISR withheld during the prior fiscal year (ejercicio fiscal). This deadline was confirmed by the Resolución Miscelánea Fiscal (RMF) issued annually by the SAT, and failure to comply within the prescribed period constitutes an infraction under Article 83 of the Código Fiscal de la Federación (CFF).

The constancia de retenciones serves multiple critical functions in the Mexican tax system. First, it enables the SAT's pre-filled annual declaration service (declaración anual prellenada) to accurately reflect the employee's wage income, allowing straight-through reconciliation with the CFDI de nómina (electronic payroll receipts) issued by the employer throughout the year. Second, where an employee worked for multiple employers during the year, the constancias from all employers must be combined to calculate the correct annual ISR liability under Articles 152 and 96 LISR. Third, the certificate documents any subsidio para el empleo (employment subsidy) credits applied under Article 94 LISR and the Decreto del Subsidio para el Empleo, which reduce the effective tax burden on low-income workers.

Under the CFDI de nómina regime implemented by the SAT through the Resolución Miscelánea Fiscal, employers must issue electronic payroll receipts (CFDI de nómina versión 4.0 — cfdi:Complemento de Nómina) for every payroll payment. The constancia de retenciones is not itself a CFDI but must be consistent with the CFDI de nómina records in the SAT's tax information database (buzón tributario). Discrepancies between the constancia and the CFDIs de nómina may trigger an automated notification from the SAT requesting clarification or an amended annual declaration.

The Reglamento de la Ley del Impuesto sobre la Renta (RLISR) Article 175 establishes that the constancia must state separately: total salaries and wages (sueldos y salarios); total fees and professional services fees (honorarios) if applicable; overtime (horas extras); year-end bonus (aguinaldo); vacation premium (prima vacacional); profit-sharing (PTU — Participación de los Trabajadores en las Utilidades de las Empresas); and other taxable income components. Exempt income concepts — up to the exempt limits established in Article 93 LISR — must also be identified separately.

For workers who terminate employment during the year, the outgoing employer must issue the constancia de retenciones at the time of termination or no later than 15 February of the following year. The constancia is also required for independent contractors (honorarios asimilados a salarios) and for individuals receiving fees from a single payer where the payer withholds and remits ISR on their behalf under Article 94 LISR.

When an employer undergoes a corporate restructuring — merger (fusión), spin-off (escisión), or change of controlling entity under the Ley General de Sociedades Mercantiles — the successor employer must issue constancias covering the full fiscal year for all transferred workers, correctly reflecting income paid by both the predecessor and successor entities so that workers have the complete annual data needed to file their annual declaration under LISR Article 150.

An ISR Withholding Certificate Mexico is required in every employment and fee-withholding relationship where ISR has been withheld and remitted to the SAT during a fiscal year. The primary trigger is the annual compliance obligation under LISR Article 99 Fraction III — every employer must issue the constancia by 15 February regardless of whether the employee requests it.

The certificate is needed when an employee files their annual ISR declaration (declaración anual) with the SAT, which is mandatory for workers who: earn income from two or more employers simultaneously during any part of the year; earn annual income exceeding $400,000 MXN; receive income not subject to employer withholding; or receive income from sources other than wages (dividends, rental income, capital gains) during the same fiscal year, under Article 150 LISR. The constancia de retenciones provides the precise data required to complete Form 10 (Declaración Anual de Personas Físicas) in the SAT portal.

The document is needed when an employee resigns, is terminated, or retires during the fiscal year — the employer must issue a proportional constancia reflecting wages paid and ISR withheld through the termination date. When calculating the liquidación (severance) or finiquito (final settlement), the constancia is used to determine the ISR applicable to any preferential payments under Article 96 LISR.

A constancia is required when an employer makes the annual ISR adjustment (ajuste anual de ISR) under Article 97 LISR — a process where the employer recalculates each employee's annual ISR liability using the annual tariff, compares it to provisional monthly withholdings, and either collects any underpayment or refunds any overpayment in the February payroll. The constancia documents the result of this reconciliation for the employee.

The document is also necessary for workers seeking credit from INFONAVIT (Instituto del Fondo Nacional de la Vivienda para los Trabajadores) — mortgage applications require wage and withholding verification that the constancia provides. Similarly, applications for Afore (Administradoras de Fondos para el Retiro) voluntary savings withdrawals may require tax documentation of withholdings. Notaries (notarios públicos) processing real estate transactions for salaried buyers routinely request the most recent constancia de retenciones as proof of income and tax compliance.

A valid ISR Withholding Certificate Mexico under LISR Article 99 Fraction III and the Reglamento de la Ley del Impuesto sobre la Renta Article 175 must contain the following essential elements to satisfy SAT filing requirements and enable accurate annual declaration preparation.

Employer (Retenedor) Identification: The employer's full legal name (razón social or nombre completo for personas físicas), RFC (Registro Federal de Contribuyentes), tax domicile (domicilio fiscal), IMSS Employer Registration Number (Número de Registro Patronal IMSS), and signature of the legal representative or authorised signatory. The RFC must match the RFC registered as the CFDI de nómina issuer in the SAT's CFDI verification system.

Worker (Trabajador / Perceptor) Identification: The employee's full name, RFC with homoclave, CURP (Clave Única de Registro de Población), IMSS Número de Seguridad Social (NSS), and the period covered by the certificate (fiscal year or partial year for mid-year terminations).

Annual Income Breakdown: Detailed listing of all taxable and exempt income paid during the covered period, including: sueldos y salarios gravados (taxable wages); ingresos exentos by concept (aguinaldo exempt up to 30 UMAs under Article 93 Fraction XIV LISR; vacation premium exempt up to 15 UMAs under Article 93 Fraction XI; overtime exempt up to double the ordinary wage for three weeks per year under Article 93 Fraction I); PTU — Participación de los Trabajadores en las Utilidades gravada y exenta; prima dominical; and any other employment income concepts under the payroll CFDI complement.

ISR Withholding Detail: Total ISR withheld (ISR retenido) from monthly payroll; any additional ISR collected in the annual adjustment (diferencia ISR cobrada en ajuste anual); total ISR refunded in the annual adjustment (ISR devuelto en ajuste anual); and net ISR remitted to the SAT through IMSS or direct monthly declarations under Articles 96 and 97 LISR.

Subsidio para el Empleo: Total subsidio para el empleo credited to the worker (subsidio acreditado) and the total subsidio paid by the employer where the credit exceeded actual ISR withholdings — documenting entitlement to reimbursement from the SAT by the employer under the Decreto del Subsidio para el Empleo.

Social Security Deductions: Employee IMSS contributions (cuotas IMSS del trabajador) deducted from wages, broken down by insurance branch (Seguro de Enfermedades y Maternidad, Invalidez y Vida, Cesantía en Edad Avanzada y Vejez — CEAV, Guarderías); INFONAVIT employee contribution (5% of SBC — Salario Base de Cotización); and voluntary AFORE contributions.

Fiscal Year and Signature: The fiscal year (ejercicio fiscal) covered, place and date of issuance, and signatures (or digital seal) of the employer's legal representative and the employee acknowledging receipt. The employee acknowledgment does not constitute agreement that the figures are correct — employees retain the right to dispute discrepancies through the SAT's correction procedures.

Forms-legal.com provides this ISR Withholding Certificate Mexico template as a reference. Employers must ensure their payroll systems generate the constancia directly from CFDI de nómina data and that figures are reconciled with SAT records before issuance — a contador público or payroll specialist (especialista en nómina) should review the certificate before delivery to employees. Related documents include the Recibo de Nómina for individual payroll payment records and the Constancia de Situación Fiscal for verifying employee RFC data required under CFDI 4.0 nómina issuance rules.

Retention Period: Under CFF Article 30, employers must retain copies of all constancias de retenciones issued to workers for a minimum of five fiscal years — the same retention period applicable to CFDI de nómina records, payroll accounting entries, and supporting documentation for ISR withholding calculations. The SAT's Administración General de Fiscalización de Grandes Contribuyentes (AGGC) and regional audit units may request production of constancias and supporting CFDI records in any audit covering the corresponding fiscal years. Digital retention in SAT-compliant electronic accounting systems (contabilidad electrónica) under CFF Article 28 is acceptable, provided the records are accessible in the XML formats required by the SAT's electronic accounting rules.