A SAT audit is not an indication of wrongdoing. It is an administrative procedure that any Mexican taxpayer can face, and foreign-owned corporations in Mexico are frequent targets because cross-border transactions—intercompany loans, royalties, management fees, and dividend distributions—attract SAT scrutiny by their nature. The outcome of an audit depends less on the original tax position than on how the company responds: the quality of documentation provided, the procedural choices made, and whether legal counsel is involved from the start.
Related issues may require complementary legal analysis, depending on the transaction and operating structure.
The three SAT audit modalities
Desk audit
The desk audit is the most common audit type for foreign-owned corporations. SAT issues a formal requirement (requerimiento) requesting documents and information—typically CFDI records, bank statements, tax returns, and financial statements—within a specified deadline.
The desk audit is conducted remotely. SAT auditors analyze the submitted materials and compare them against the CFDI information in SAT's own systems, banking information obtained from CNBV, and customs data. CFDI reconciliation errors, unexplained bank credits, and discrepancies between income reported and deposits received are the primary triggers for follow-up requirements or formal assessments.
Response timelines are strict. A company that receives a requerimiento has a legally defined period to respond—typically 15-20 working days, with limited extensions. Failing to respond within the deadline allows SAT to proceed with a presumptive assessment based on the information it has.
Field audit
The field audit authorizes SAT auditors to physically visit the company's registered address, inspect books and records, interview employees, and request documents. The auditors must present an audit order (orden de visita) identifying the taxpayer, the tax periods covered, and the specific taxes under review.
The field audit is governed by CFF Art. 46-A, which caps its duration at 12 months from the date the auditors present the order. This 18-month cap for large taxpayers (contribuyentes grandes) is enforced, meaning SAT must conclude the audit within that period or the legal basis for the audit expires.
During the field audit, companies have the right to designate legal representation, to have counsel present during all interactions with auditors, and to respond to preliminary findings (acta final de visita) before a formal assessment is issued.
Electronic review
The electronic review is the newest and fastest-expanding audit modality. SAT initiates it based entirely on digital information—CFDI records from all Mexican taxpayers in the company's supply chain, banking information, and third-party filings—without any physical document request.
SAT generates a pre-liquidation (preliquidación) identifying the specific discrepancy it believes it has found and gives the company 15 working days to either accept the discrepancy and pay or contest it. Electronic reviews are faster than traditional audits and are typically focused on a specific, narrow issue: an unmatched CFDI deduction, a specific intercompany transaction, or a LIVA refund claim SAT wants to verify.
Taxpayer rights
Mexico's CFF and the Carta de los Derechos del Contribuyente establish clear procedural rights for companies under audit:
- Right to representation: A company can designate legal or tax counsel to represent it in all interactions with SAT. All SAT communications should be channeled through designated representatives.
- Right to respond: Before SAT issues a formal assessment, it must give the taxpayer an opportunity to respond to preliminary findings and submit evidence. This response window—typically 20 working days under the ACTA Final process—is the most important procedural protection available.
- Right to PRODECON assistance: The Procuraduría de la Defensa del Contribuyente is an independent government body that represents taxpayers, provides free legal advice on audits, and facilitates the acuerdo conclusivo procedure.
- Right to request a suspension: During the audit, a taxpayer can request an extension or suspension of the response period in limited circumstances. Collection of a final assessment can be suspended by posting a guarantee while the assessment is appealed.
What SAT auditors look for
Foreign-owned corporations are audited with a focus on cross-border transactions:
- CFDI inconsistencies: SAT compares the CFDIs a company issues (as a seller) against the CFDIs it receives (as a buyer) and checks both against reported income and deductions. A deduction claimed for a payment to a supplier, when that supplier did not issue a CFDI, is a red flag.
- Unreported bank income: SAT obtains banking information through the CNBV and compares deposits against reported income. Deposits not matched to invoiced income trigger questions about unreported revenue.
- Transfer pricing positions: Intercompany transactions are scrutinized against arm's-length standards. A Mexican subsidiary consistently reporting losses while paying management fees or royalties to its foreign parent will face transfer pricing review.
- Non-deductible expenses: Expenses that fail the "strictly necessary" test, lack supporting CFDIs, or are payments to related parties without withholding compliance are denied and generate tax adjustments plus penalties.
- LIVA mismatches: Discrepancies between VAT collected and VAT paid, or between IVA on imports and customs declarations, generate LIVA adjustments.
The acuerdo conclusivo: penalty elimination through PRODECON
The acuerdo conclusivo procedure (CFF Art. 69-C) is one of the most powerful tools available to a taxpayer under audit. It allows the taxpayer to negotiate the disputed tax position directly with SAT through PRODECON as a mediator before a formal assessment is issued.
The critical feature of the acuerdo conclusivo: the first time a taxpayer uses it, 100% of penalties are waived. Only the base tax and surcharges remain. For a transfer pricing adjustment or a large CFDI dispute where penalties would be 55-75% of the omitted tax, this reduction is financially transformative.
To qualify, the company must file the acuerdo conclusivo request while the audit is still open—after the preliminary findings are communicated but before the final assessment. Once an assessment is issued, the procedure is no longer available.
PRODECON facilitates meetings between SAT and the taxpayer, provides independent technical opinions on disputed issues, and produces an agreement document that resolves the audit. SAT is not obligated to accept the taxpayer's position, but in practice, agreed-upon resolutions are common on factual disputes.
Strategic choices during an audit
The strategic question in every audit is when to cooperate and provide additional information versus when to withhold and preserve positions for litigation.
Voluntarily providing information beyond what the SAT specifically requested can open new audit issues. On the other hand, refusing to provide clearly requested documents increases the risk of a presumptive assessment based on incomplete information.
The optimal approach:
- Respond to every SAT requirement fully and on time.
- Provide only the documents specifically requested.
- Frame document submissions with cover letters that contextualize the information and preserve legal arguments.
- Evaluate the acuerdo conclusivo at the preliminary findings stage if penalties are material.
- If the position is legally sound, preserve litigation rights by not accepting disputed findings.
Continue your legal review
Broaden the analysis with our guide to tax optimization for Mexican businesses.
Prepare for the next stage with tax consulting within a business context in Mexico.
Explore the related legal considerations in legal strategies for fiscal dispute resolution with the SAT.
Frequently asked questions
Generally, no. Once SAT completes an audit of a specific tax period and issues a final resolution, it cannot reopen the same period for the same tax unless there is fraud or falsification or if new information comes to light that was concealed by the taxpayer. This protection makes it important to resolve all open issues during the initial audit rather than leaving them pending.
SAT proceeds with a presumptive assessment based on the information it has, which invariably produces a higher tax liability than the actual one. Failing to respond also strengthens any future assessment because the taxpayer cannot later claim SAT lacked information. A response is always required, even if the response is a partial or documented objection.
A field audit is more resource-intensive for both parties, but it is not inherently more serious. Field audits give SAT access to physical records, employee interviews, and broader document requests. However, field audits are also more constrained by procedural rules, and the 12-month time limit creates pressure on SAT to conclude. For significant intercompany transactions, the additional procedural protections of a field audit can work in the taxpayer's favor.
Desk audits are typically resolved in 6-12 months from the initial requerimiento to a final assessment. Field audits can run up to 12 months under CFF Art. 46-A. Electronic reviews are faster—3-6 months from initial notification to resolution. Litigation after the audit adds another 8-24 months before TFJA.
Yes. The procedural choices made in the first 30 days of an audit—what documents to provide, how to characterize transactions, whether to request extensions, and whether to pursue the acuerdo conclusivo—have lasting consequences. Retaining Mexican legal counsel with audit defense experience at the outset is significantly less costly than correcting procedural errors made without counsel.