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1. Introduction
In recent years, the Mexican tax system has undergone a significant transformation toward a digital taxation model, in which the tax authority increasingly uses technological tools and interconnected databases to verify taxpayers' compliance with their tax obligations.
In this context, the SAT has developed various mechanisms that allow tax information from multiple sources to be automatically integrated.
In this regard, one of the most significant advances in this area has been the incorporation of preloaded information in the annual income tax return (ISR) for legal entities, which mainly consists of data obtained from tax receipts for the fiscal year.
The information that appears pre-filled on the annual return comes from, among other sources:
- Nominal income reported in the monthly provisional income tax return statements filed during the fiscal year.
- CFDIs related to returns, discounts, and/or rebates.
- Tax withholdings made for concepts such as salaries, income assimilated to salaries, leases, and obligations under the Simplified Trust Regime (RESICO).
- Other data originating from previous fiscal years, including tax losses, payments made abroad, dividends, and employment subsidies.
The incorporation of this information aims to facilitate compliance with tax obligations, reduce data entry errors, and allow the tax authority to perform automated cross-checks of information across different systems.
However, the existence of preloaded information does not imply that taxpayers may omit reviewing their annual return. On the contrary, it is essential for companies to carefully analyze the information displayed in the SAT system in order to confirm that it corresponds with the entity’s actual accounting and tax records for the fiscal year.
2. Preloaded Information in the Annual Income Tax Return
As previously mentioned, within the annual income tax return filing system, the SAT incorporates various data that are preloaded in the database maintained by the tax authority.
The presence of this data allows the tax authority to perform a preliminary verification of the consistency between information reported in issued and received tax invoices and the monthly federal tax returns filed by the taxpayer.
Among the main items that may appear pre-filled on the annual tax return are the following:
Monthly Advanced Income Tax Payments Filed During the Fiscal Year
One of the most relevant elements reflected in the annual Income Tax return corresponds to income obtained during the fiscal year, which is derived from the amounts reported by the taxpayer in the monthly advanced Income Tax payments filed throughout the year.
In this context, income CFDIs issued by taxpayers constitute one of the primary sources of information used by the tax authority to identify such income, since the information contained in these invoices is incorporated into SAT databases and serves as a reference for pre-filling and validating the income reported in monthly advanced Income Tax payments and subsequently in the annual Income Tax return.
The information contained in income CFDIs is used to prefill the monthly advanced Income Tax returns, allowing the SAT system to suggest the income obtained during the period based on the income CFDIs issued in each month of the fiscal year.
In this manner, monthly advanced Income Tax returns reflect the income reported by the taxpayer on a cumulative basis throughout the fiscal year, which is later considered within the annual Income Tax return. Consequently, the income appearing in said return largely derives from the information declared month by month in the monthly advanced Income Tax payments.
This mechanism allows the SAT to perform automatic cross-checks between the income CFDIs issued, the income recorded in the taxpayer’s electronic accounting, the amounts reported in advanced monthly Income Tax payments, and the income reflected in the annual Income Tax return.
For this reason, it is essential for taxpayers to verify the consistency among these elements, as any discrepancy between issued CFDIs, accounting records, and filed returns may generate inconsistencies detectable by the tax authority, which could ultimately result in audits or inquiries regarding the correct determination of income obtained during the fiscal year.
Employee Profit Sharing (PTU)
Another concept that may appear within the preloaded information of the annual return is Employee Profit Sharing (PTU) paid during the fiscal year.
PTU constitutes a labor obligation that companies must pay to their employees when taxable income is generated during the fiscal year. However, from a tax perspective, PTU paid may have relevant implications in determining the annual Income Tax.
Therefore, the annual return system may incorporate information related to the PTU effectively paid, which is prefilled from the payroll CFDIs issued during the fiscal year.
In this regard, it is advisable to verify that the PTU amounts reflected in payroll CFDIs match the accounting records, ensuring their proper application in the determination of the taxpayer’s annual Income Tax.
Withholdings Made by the Taxpayer
The annual Income Tax return may also incorporate information related to Income Tax withholdings made by the taxpayer during the fiscal year, particularly in relation to payments for:
- Salaries and wages, and income assimilated to salaries;
- Professional services and lease payments and;
- Payments made to taxpayers under the Simplified Trust Regime (RESICO).
Information corresponding to Income Tax withholdings made during the fiscal year may appear preloaded in the annual return, based on the data previously reported by the taxpayer in the monthly withholding tax returns filed during the year.
In this regard, it is important for taxpayers to verify that the withholding amounts reflected in the annual Income Tax return match the amounts actually reported in the monthly returns, as well as the information contained in the CFDIs received for the corresponding period, likewise, it is advisable for these amounts to be reconciled with the expenses recorded in the taxpayer’s accounting records, in order to ensure consistency between the information reported, the tax invoices, and the accounting records for the fiscal year.
Returns, Discounts, and/or Rebates
In the course of their operations, taxpayers may grant discounts and/or rebates to their customers or receive full or partial returns of goods. These transactions are documented through the issuance of an expense CFDI (credit note).
In accordance with the Income Tax Law, returns, discounts, and rebates on sales must be considered authorized deductions, and therefore should not be directly subtracted from taxable income but rather included within the corresponding deductions section.
Historically, these transactions were manually recorded in the annual Income Tax return forms within the deductions section. However, beginning with the previous fiscal year, a specific section was incorporated within the deductions area, where such information appears preloaded based on the data contained in the expense CFDIs issued by the taxpayer.
Relevant Changes with Regards to CFDIs Derived from the 2026 Tax Reform
Within the framework of the 2026 Tax Reform, several adjustments were introduced regarding electronic invoicing, with the objective of strengthening SAT’s oversight and control mechanisms.
Among the most significant changes are the following:
- Requirement for authenticity of transactions.
CFDIs must now support real and effectively carried out transactions. If a tax invoice documents non-existent or simulated operations, it will lose its tax validity, thereby reinforcing control over the substance and authenticity of invoiced transactions.
- Expanded Faculties of Verification for the SAT
The tax authority now has broader powers to verify the authenticity of transactions documented in CFDIs. It may request supporting documentation demonstrating the existence of the transaction and may adopt measures such as the restriction or cancellation of the Digital Seal Certificate (CSD) when irregularities are detected.
- Expansion of Penalties Related to Improper Invoicing
The responsibilities and penalties applicable to individuals who issue, use, or facilitate the issuance of CFDIs documenting non-existent transactions have been expanded. These sanctions may include administrative penalties and, in certain cases, criminal liability.
- Adjustments to CFDI Cancellation Rules
The deadline for canceling tax invoices has been extended until the month in which the corresponding annual Income Tax return is filed, allowing taxpayers to correct invoicing errors from the fiscal year, provided that the applicable regulatory requirements are met.
3. Importance of Reviewing Preloaded Information in the Annual Income Tax Return Against CFDIs
The incorporation of preloaded information in the annual Income Tax return represents a significant advancement in the digitalization of the tax system. However, it also implies that the tax authority now has greater tools to identify inconsistencies in taxpayers’ tax information through automated cross-checking of data derived from CFDIs, monthly tax returns, and other databases maintained by SAT.
For this reason, prior to filing the annual Income Tax return, it is advisable for companies to conduct a comprehensive review of several elements, including:
- The reconciliation between issued income CFDIs and income recorded in accounting records.
- The review of Income Tax withholdings made and paid to the tax authority through monthly tax returns.
- The review of expense CFDIs related to returns, discounts and/or rebates, verifying that their amounts match the corresponding accounting records.
A comprehensive review of these elements allows companies to confirm that the information preloaded by SAT is consistent with the taxpayer’s accounting records and CFDIs.
4. Conclusion
A comprehensive review of the accounting records and CFDIs allows companies to verify that the information preloaded in the annual Income Tax return is consistent with the transactions actually carried out during the fiscal year. In this way, potential discrepancies can be identified and corrected in a timely manner before filing the annual return, thereby helping ensure the proper determination of the tax and reducing the likelihood of reviews by the tax authority.
Authors: Juan Carlos Rodríguez Domínguez, CPA, and José Luis Rosas Galicia, CPA.
