Version 1.2 of the payroll complement has more than a hundred validation rules, which the SAT (Mexico's tax authority) publishes in its error matrix. The certification provider checks many of them when stamping the CFDI (the electronic payroll receipt), but not all: some inconsistencies get through and only surface later, during an audit.
The mistakes that come up most
| Mistake | Where it comes from | How to fix it |
|---|---|---|
| Employee name, RFC (tax ID) or postal code | They don't match the employee's tax status certificate | Check the data with the SAT's bulk RFC validator |
| Seniority in the wrong format | It must be expressed as P#W (weeks) or P#Y#M#D | Calculate it from the start date of the employment relationship |
| Exemptions above the limit | UMA-based caps applied incorrectly (the UMA is Mexico's reference unit for caps) | Review the limits in Article 93 of the Income Tax Law |
| Subsidy paid in cash | Other payment 002 with an amount larger than the ISR (income tax) | Since 2024 the subsidy is no longer paid in cash |
| Employer registration and SDI on asimilados receipts | These fields don't apply to regime 09 | Remove them from asimilados receipts |
| Dates that don't add up | End date earlier than start date, or wrong number of days paid | Review the period before stamping |
How to handle it day to day
- Before stamping, check your employees' tax data against their certificate.
- Confirm the period, dates and days paid for each payroll.
- Validate your XML files every period, before closing the month.
- If you find a mistake, fix it with a replacement CFDI: it is much easier when you catch it early.
For the subsidy case, see the 2026 ISR tax table and employment subsidy; for regime 09 receipts, see what asimilados are and how they are stamped.
Legal basis
- Federal Tax Code, Articles 29 and 29-A.
- Income Tax Law, Article 99, Section III.
- Annex 20 of the Miscellaneous Tax Resolution and the filling guide for the payroll receipt and its complement.
- Payroll complement error matrix published by the SAT.
In Nomikhor, taxable and exempt amounts are split automatically using current caps, ISR and subsidy are calculated on their own and stamping is unlimited, so you can re-stamp whenever you need to without worrying about the cost.