CFDI 4.0, fuel, and mileage reimbursement in Mexico: what changed in 2026
SAT updated the CFDI 4.0 filling guide in 2026. How it affects fuel reimbursement.
What changed in 2026
SAT published an updated *CFDI 4.0 filling guide* in March 2026 with two material changes for fuel reimbursement: the product code 15101514 now requires unit code LTR for liquid fuels, and CFDIs above MXN 10,000 must include the *NumeroPedimento* field or reference to the station ticket. Stations rolled out the change between March and June 2026; CFDIs in the old format are now being rejected by SAT post-emission validation.
Two reimbursement routes
**Route A**: corporate card pays for fuel; CFDI issued directly to the company. Cleanest option, full ISR and VAT deduction.
**Route B**: employee pays personally, receives a CFDI in their name, requests reimbursement. The company reimburses but **cannot deduct VAT** (CFDI not in the company's name); only the net amount as a documented expense.
Route A is preferable wherever the operation supports it.
Post-emission validation
SAT escalated post-emission validation in 2026: syntactic validation, catalog checks, cross-reference with the active service-station register, and new 2026 cross-check with station inventory reported under Annex 30 fiscal controls. A CFDI with any inconsistency is flagged invalid and the deducting company gets a *carta invitación*.
Mileage vs fuel reimbursement
The 2026 change affects fuel reimbursement, not per-km reimbursement. Per-km reimbursement is governed by the trip log and internal policy — no CFDI is needed because the employee is not a provider of goods/services. A common mistake: companies asking employees for a CFDI for the per-km reimbursement. There is none to issue.
Cash payment trap
ISR Law Art. 27 still requires fuel paid by credit card, debit card, registered check, or transfer to be deductible. **Cash fuel is non-deductible** regardless of CFDI. Operational fix: policy requires card payment with documented emergency exceptions only.
Checklist for 2026
1. Update the accounting system's CFDI validation module to the March 2026 SAT version. 2. Push corporate cards to drivers. 3. Separate per-km policy from fuel-reimbursement policy. 4. Cross-validate CFDI vs trip log before payment. 5. Retain rejected CFDIs with the SAT reason for 5 years.