Filing format and deadlines
You need to file monthly tax returns electronically through the SAT portal. If your Constancia de Situación Fiscal shows a monthly filing requirement, your return and any related tax payments are generally due by the 17th of the following month.
Depending on the sixth numeric digit of your RFC, this deadline may be extended by 1 to 5 business days. If the return generates a balance due, you need to pay it within the designated timeframe.
Understanding your tax return
Your monthly reporting requirements depend on the obligations listed in your Constancia de Situación Fiscal and shown on the SAT portal.
| ISR (Income Tax) | ISR is calculated on your net income after allowable deductions |
| IVA (Value-Added Tax) | IVA is calculated as the difference between the VAT collected from clients and the creditable VAT paid on qualifying business expenses |
| Otros conceptos | Additional sections SAT shows based on your specific tax regime |
This may include IEPS for certain goods and services, along with other adjustments or payments relevant to your activity.
The return may also include retenciones (tax withholdings made by clients or digital platforms), sales returns or refunds, discounts, canceled CFDIs, and other adjustments.
Preparation checklist
The SAT system may pre-fill parts of your return using existing data, but the information may not always be complete or accurate. Before filing, reconcile the pre-filled data against your actual income, expenses, payments and withholdings.
Recommended review steps:
1. Verify issued CFDIs to make sure your income is recorded correctly
2. Review deductible expenses and received CFDIs
3. Confirm that all canceled or replaced CFDIs are properly accounted for
4. Verify your tax withholding amounts
5. Reconcile the final figures with your bank statements and resolve any discrepancies
Special cases to consider
Zero return (Declaración en ceros)
If a monthly filing obligation applies, having no income during the reporting month doesn't remove the filing requirement. In this case, file a zero return.
Annual income exceeding MXN 4 million
If your total income exceeds MXN 4 million, check separately whether additional obligations apply, such as DIOT and Contabilidad electrónica.
| DIOT | An informational return that details your transactions with suppliers and the associated IVA |
| Contabilidad electrónica | The requirement to keep and submit your accounting records to SAT in an electronic format |
Important: Always compare your current tax obligations with the latest version of your Constancia de Situación Fiscal.
Paying your taxes
When you file your return successfully, the SAT portal generates a línea de captura and shows the payment deadline. The línea de captura is a unique reference code you can use to pay through your banking app or in person at a branch. Save your payment receipt (comprobante de pago) as official proof of compliance.
Why you should consider a professional
Managing tax obligations under these regimes can be complex. It requires specialized knowledge and continuous monitoring of SAT updates. To reduce the risk of late filings, incorrect submissions, SAT notices (requerimientos), and issues that may affect, suspend, or even halt your business operations, consider delegating tax return preparation to a qualified tax accountant.
Regulatory framework
Articles 17-H Bis, 28, and 31 Código Fiscal de la Federación — CFF
Articles 106 and 113-A–113-D Ley del Impuesto sobre la Renta — LISR
Articles 5, 5-D, 18-J–18-M, and 32, section VIII, Ley del Impuesto al Valor Agregado — LIVA
Rules 2.8.1.17 and 2.8.3.1 Resolución Miscelánea Fiscal para 2026 — RMF 2026