The 2026 Miscellaneous Tax Resolution and the New Face of Tax Control in Mexico

For years, Mexico’s tax policy has evolved through a combination of visible legislative reforms and quiet administrative adjustments. The 2026 Miscellaneous Tax Resolution clearly belongs to the latter category—yet its impact will be profound.

Published on December 28, 2025, the 2026 Miscellaneous Tax Resolution (RMF 2026) does not introduce new taxes nor does it modify tax rates. What it does instead is redefine, with greater precision, how, when, and under what standards taxpayers must demonstrate that what they report reflects a real, consistent, and sustainable operation.

In practical terms, the message from Mexico’s Tax Administration Service (SAT) is unmistakable: the era of merely formal compliance is over.

More Data, More Cross-Checks, Less Margin for Error One of the central pillars of RMF 2026 is the consolidation of Mexico’s digital tax ecosystem.

The Tax Mailbox (Buzón Tributario) is reaffirmed as the primary channel for filings, requests, notifications, and legal defenses. At the same time, the CFDI ceases to be merely a tax receipt and becomes the core input for automated tax analysis.

Today, the tax authority no longer verifies only whether an invoice exists, but whether it:

• Is consistent with contracts, payments, and tax returns.
• Aligns with the taxpayer’s declared economic activity.
• Reflects a reasonable and sustainable business logic.

Tax audits no longer begin with on-site inspections; they start with data-driven models, massive information cross-checks, and the detection of atypical patterns.

Economic Substance: The Common Thread of RMF 2026

Although the term does not always appear explicitly, RMF 2026 is permeated by a transversal principle: economic substance.

This approach is reflected in:

• Strengthened rules on international exchange of information.
• Increased scrutiny of related-party transactions.
• Review of corporate restructurings, mergers, and spin-offs.
• Conditional permanence in regimes such as the Simplified Trust Regime (RESICO).

The authority operates under a clear premise: the information already exists, is interconnected, and can be analyzed in real time. What is now required is that taxpayers be able to explain, support, and defend that information consistently.

From Reactive Compliance to Continuous Oversight

In this new environment, some firms are rethinking their role. The challenge is no longer limited to preparing tax returns, but to continuously supervising tax operations under the same criteria applied by the tax authority.

Within this context, AS Consulting Group (ASCG) has developed ASiViewer, a proprietary tax-analysis platform supported by specialized data-analytics teams designed to continuously monitor companies’ tax operations.

ASiViewer: Tax Intelligence Based on Real Data

ASiViewer is an advanced tax data-analysis platform that evaluates a company’s entire operation using its CFDIs, tax returns, and supplements, applying criteria aligned with the algorithms and regulatory patterns employed by Mexican tax authorities.

The logic behind the platform is simple yet powerful: to transform tax data into real, actionable, near-real-time tax intelligence. Not to replace the authority, but to anticipate risks, detect inconsistencies, and align day-to-day operations with what the SAT is already observing through its own systems.

RMF 2026 confirms that this preventive, analytical, data-driven approach will cease to be a competitive advantage and will instead become an operational necessity.

Tax Incentives: Opportunities with Greater Discipline The Resolution also incorporates various tax decrees and incentives—such as Plan México, development poles, border regions, and circular economy initiatives—but with a consistent theme: no benefit is automatic.

Access to these incentives requires:

• Timely filings and notices.
• Strict compliance with applicable guidelines.
• Solid documentary, operational, and tax evidence.

In practice, tax incentives have moved beyond declarative treatment and are now managed as projects subject to continuous control and monitoring.

A Silent but Structural Shift

RMF 2026 does not seek dramatic headlines. Its objective is more structural: to normalize a tax-enforcement model based on data, traceability, and economic coherence.

For taxpayers, the challenge is no longer just to comply, but to prove that their compliance makes economic sense. For advisory firms, the challenge lies in providing support through strategic vision, technology, and continuous analysis.

It is within this balance between regulation, data, and economic reality that Mexico’s new tax standard is being defined.

And all indications suggest it is here to stay.