Filing format and deadlines
Companies need to file monthly tax returns electronically through the SAT portal. If the company's Constancia de Situación Fiscal shows a monthly filing obligation, the return and any related tax payments are generally due by the 17th day of the month after the reporting period.
Deadline extension based on RFC
SAT rules may extend this deadline by 1 to 5 business days based on the sixth numeric digit of the company's RFC:
- 1–2 → plus 1 extra business day
- 3–4 → 2
- 5–6 → 3
- 7–8 → 4
- 9–0 → 5
Always follow the deadline SAT shows for the specific filing and payment.
If the return generates a tax balance due, the company needs to pay it within the timeframe SAT indicates, usually through the línea de captura generated after filing.
Understanding the company's monthly return
Monthly reporting requirements depend on the company's tax regime, the obligations listed in its Constancia de Situación Fiscal, and the sections shown on the SAT portal.
| ISR (Corporate Income Tax) | A monthly provisional payment toward the company's annual income tax. The calculation depends on the tax regime, prior filings, provisional payments, applicable rules, and information available to SAT. |
| IVA (Value-Added Tax) | IVA is calculated based on the VAT charged or collected from clients and the creditable VAT paid on qualifying business expenses, subject to applicable requirements |
| Retenciones (Withholdings) | Taxes the company needs to withhold and pay to SAT. This may include payroll withholdings, payments treated as salary, rent, professional services paid to individuals, and other transactions depending on the applicable rules. |
| Otros conceptos (Other Items) | Additional sections SAT shows according to the company's regime and obligations. This may include IEPS for certain goods and services, sector-specific obligations, adjustments, supplementary payments, or other items relevant to the period. |
The return may also reflect sales returns or refunds, discounts, canceled or substituted CFDIs, credit notes, prior payments, balances in favor and other period adjustments.
Preparation checklist
The SAT system may pre-fill sections of the return using existing information, such as issued and received CFDIs, payroll CFDIs, prior provisional payments and historical filing data. Because pre-filled information may be incomplete or inaccurate, reconcile it against the company's accounting records, bank statements, payroll data and supplier information before filing.
Recommended review steps:
1. Verify issued CFDIs to ensure income is recognized correctly
2. Review received CFDIs, supplier invoices and creditable IVA
3. Confirm that canceled, substituted, or replaced CFDIs and credit notes are properly accounted for
4. Review payroll CFDIs, salaries, payments treated as salary and related payroll withholdings
5. Verify tax withholdings the company made or had withheld from it
6. Reconcile the final figures with bank statements, accounting ledgers and the trial balance. Resolve any discrepancies before filing.
7. Review prior provisional payments, balances in favor and relevant data from the annual return, where applicable
Special cases and additional obligations
| Zero return (Declaración en ceros) | If a monthly filing obligation applies, having no income or transactions during the reporting month doesn't automatically remove the filing requirement. File a zero return when the SAT portal and the company's obligations require it. |
| Payroll-related obligations | If the company has employees or makes payments treated as salary, review payroll CFDIs and payroll tax withholdings before filing. Separate obligations for social security, the housing fund and state payroll taxes may also apply under their own rules and deadlines. |
| DIOT | An informational return that reports transactions with suppliers and the related IVA, including payment, withholding, crediting, and IVA charged where applicable |
| Contabilidad electrónica | The obligation to keep and electronically submit accounting records to SAT. This may include the chart of accounts, monthly trial balances and when requested, journal entries or vouchers (pólizas) and auxiliary ledgers. |
Important: Always verify the company's current tax obligations against the latest version of its Constancia de Situación Fiscal and monitor SAT communications through the Buzón Tributario.
How to pay taxes
When the company files the return successfully, the SAT portal generates a línea de captura and shows the deadline. The línea de captura is a unique payment reference the company can use to pay through its bank's online banking. Keep the payment receipt, or comprobante de pago, as official proof.
Why consider a professional
Corporate tax compliance in Mexico requires ongoing accounting control, careful reconciliation of CFDIs and bank movements, payroll and withholding review, SAT obligation monitoring and strict deadline management.
To reduce the risk of late filings, incorrect submissions, SAT notices (requerimientos), financial penalties, negative compliance effects and operational restrictions, consider delegating tax filing preparation to a qualified tax accountant.
Operational restrictions can include limitations on the company's ability to issue CFDIs if SAT restricts the Certificado de Sello Digital (CSD).
Regulatory framework
Articles 17-H Bis, 28–31, 81, and 82 Código Fiscal de la Federación — CFF
Articles 9, 14, and 76 Ley del Impuesto sobre la Renta — LISR
Articles 1, 1-A, 5, 5-D, and 32 Ley del Impuesto al Valor Agregado — LIVA
Articles 1, 2, 5, and 19 Ley del Impuesto Especial sobre Producción y Servicios — LIEPS
Article 5.1 of the Decree published on December 26, 2013
Rules 2.8.1.5, 2.8.1.6, 2.8.3.1, 3.9.15, 3.9.16, and 4.5.1 of the Miscellaneous Tax Resolution for 2026 (RMF 2026), together with Annex 24