SAT electronic audit: how to prepare documentation for vehicle reimbursements
Guide to responding to SAT electronic reviews via Buzón Tributario with legal deadlines and monthly XML accounting.
What is a SAT electronic audit
The electronic review is a verification power under article 53-B of the Federal Tax Code that lets SAT audit taxpayers entirely through digital channels[^cff-53b]. All communication runs through the Buzón Tributario, mandatory for legal entities since 2014[^buzon-sat].
Buzón Tributario as the single channel
The Buzón is the official electronic notification system. SAT publishes resolutions and notices and the taxpayer must check the inbox at least every three calendar days. A notification is deemed served on the fourth business day after delivery if the document is not opened[^buzon-sat].
Typical review sequence
SAT detects inconsistencies through CFDI cross-matching and issues a provisional resolution with a preliminary assessment. The taxpayer has fifteen business days to present evidence or accept with a 20% penalty discount[^cff-53b].
Legal deadlines
Fifteen days to rebut the provisional resolution, ten additional days for a second information request and forty days for SAT to issue the final resolution. All deadlines are business days starting the day after effective notification.
Minimum documentation for vehicle reimbursements
Keep a detailed logbook (origin, destination, date, kilometers, business purpose), fuel CFDI with electronic payment, an internal policy signed by management, transfer receipts to the employee and a reconciliation between the log and the CFDI[^cfdi-guia].
Monthly XML electronic accounting
Legal entities file the trial balance and chart of accounts monthly in XML following Annex 24. Reimbursement accounts must use the SAT grouping code and tie to the annual return.
Response strategy
Validate the notice authenticity on the SAT portal, organize evidence in a PDF signed with the e.firma and upload it to the Buzón with a numbered index.
Errors that cost deductions
Generic logbooks, fuel CFDI paid in cash above two thousand pesos, outdated policies and accounts outside the chart filed in electronic accounting are the most common findings. Keep all evidence for five years under article 30 of the Federal Tax Code.