Can I pay a fixed monthly per diem without proof?

No. Fraction XVII requires actual disbursement and CFDI proof; a fixed monthly allowance without receipts is reclassified as taxable salary and raises the IMSS base.

What if the CFDI is issued to the employee instead of the employer?

The employer loses the deduction and, without proper reimbursement documentation, the SAT may treat the amount as taxable income for the employee.

What additional evidence should I keep beyond the CFDI?

Trip logbook, agenda or invitation, counterparty emails, event photos and, when applicable, a visit report signed by the customer.

Mexican income tax on per diems: when it is employee income and when it isn't

Rodrigo Vázquez — Mexican Tax Specialist (SAT, CFDI)

Published: 4/28/2026 • Last reviewed: 4/28/2026 • 8 min read

Article 93 fraction XVII of the LISR: requirements for per diems not to be taxable income for the employee and mistakes that lead the SAT to reclassify them as salary.

Per diems (viáticos) are one of the items most often audited by the Mexican SAT because two sensitive tax effects coexist: the employer's deduction and the employee's income exemption. When documentation fails, what looked like a reimbursement is reclassified as taxable salary.

Legal framework: Article 93 fraction XVII LISR

Article 93 of the Income Tax Law lists exempt income for individuals. Fraction XVII states that per diems are not accruable income when they are actually spent in the employer's service and supported by documentation that meets tax requirements[^lisr-93]. The exemption is not automatic.

Requirement 1: actual disbursement for the employer

A fixed monthly allowance is not enough. The expense must be real, with date, place, business purpose and a receipt per concept.

Requirement 2: support with CFDI

Each per diem must be backed by a CFDI in the employer's name where applicable (lodging, air transport, restaurant meals, fuel). The CFDI 4.0 Filing Guide sets the mandatory fields[^rmf]. A ticket without CFDI does not prove the expense.

Requirement 3: link to the job

The employee must have an active employment relationship and the trip must relate to their duties. Authorities may request the contract, organization chart, event invitation or visit order.

Cap without receipt

LISR and the Miscellaneous Tax Resolution allow part of food per diems to be supported with credit/debit card without CFDI, within daily caps that differ for domestic and foreign destinations[^sat-viaticos]. Lodging and transport always require CFDI.

Typical reclassification cases

The SAT reclassifies per diems as taxable income and as IMSS contribution base when fixed monthly amounts are paid without proof, CFDI are missing, the business purpose is not evidenced, the employee did not actually travel, or amounts exceed market value.

Impact on the employer

Reclassification means paying withheld income tax, surcharges, inflation adjustment and IMSS/INFONAVIT differentials, plus losing the deduction. Penalties often exceed 100% of the misdocumented amount.

Good practices

Written policy with caps per destination, trip logbook, CFDI from day one, evidence of business purpose, and monthly reconciliation between per diem paid and CFDI received.