Electronic reviews allow the SAT to cross-check CFDIs, returns, accounting and third-party data without starting with a physical visit. The procedure may begin with a provisional resolution and a pre-assessment delivered to the Tax Mailbox. From that moment, short deadlines run to clarify, provide evidence or self-correct. In 2026, an effective response depends on keeping evidence before the request, assigning owners and separating the legal explanation from the numerical reconciliation. Each case requires its own professional strategy.
How the authority starts and what it reviews
The Federal Tax Code authorizes electronic reviews based on information already held by the authority. The SAT can detect differences between invoiced and declared income, withholdings, deductions, payments or data reported by third parties. The act begins with the notice of a provisional resolution describing facts or omissions and may include a pre-assessment. It is not yet a final resolution, but it requires an immediate reaction. Authenticity, the legal date of notice, the fiscal year, the tax, the items and the methodology must be verified. The courtesy email does not replace the document in the mailbox. The first task is to preserve the original file and calculate the deadline using the tax calendar, not estimates.
Deadlines and options during the review
After the notice, the taxpayer generally has fifteen business days to state what is appropriate, provide documentation, rebut irregularities or prove payment. If it accepts the pre-assessment and self-corrects within that period, the law provides for a penalty equal to twenty percent of the omitted contributions, plus the applicable items. The authority may issue a second request and grant ten days to respond. Once the information is complete, it has forty business days to issue and notify the resolution. A conclusive agreement before PRODECON may also be assessed. Choosing among clarifying, correcting or challenging requires weighing the facts, evidence, financial cost and effects on other periods.
The response file
A useful reply connects each observation with a fact, legal basis, reconciliation and numbered exhibit. It is advisable to prepare a matrix showing the SAT figure, the taxpayer figure, the difference, the explanation and the supporting document. The XMLs, bank statements, accounting entries, contracts and returns must be legible and consistent; sending volume without an index hinders the review. Before filing, it is verified that the reply covers every point and that the files are not corrupted. The Supreme Court has recognized consequences when the authority issues the final resolution outside the legal forty-day period, but that control does not replace a timely defense. The acknowledgment, hash or exact copy of what was sent and a full chronology must be kept.
Key points
- The provisional resolution opens an opportunity to clarify; it must not be treated as a final determination.
- The initial deadline to respond is normally fifteen business days from the notice.
- The authority may issue a second request and then has a legal deadline to resolve.
- A matrix of observations and exhibits is more effective than sending documents without structure.
What to review
- Preserve the resolution, pre-assessment, acknowledgment and evidence of the exact date of notice.
- Reconcile each difference with CFDIs, returns, accounting, banks and contractual documentation.
- Assess early the clarification, self-correction, conclusive agreement and applicable means of defense.