In brief
The Mexican tax authority, when exercising its audit powers, requires private documents—such as contracts—to comply with the "certain date" requirement in order to be considered valid evidence supporting the taxpayer's transactions under review. The Mexican Supreme Court of Justice (SCJN) (Reg. 2021218) established the standard by defining the elements a private document must meet to be deemed to have a certainty on the date it was executed. This precedent constitutes binding case law (i.e., Jurisprudence) and is therefore mandatory.
In more detail
On 23 January 2026, the Federal Judicial Weekly published thesis No. 2031684, issued by the Second Collegiate Court (TCC) of the Auxiliary Center of the Fourth Region, based in Xalapa, Veracruz. This thesis establishes that foreign contracts must comply with the "certain date" requirement under Mexican civil law.
However, this thesis does not consider that an Apostille may verify the existence and legality of the signature/position/seal of a foreign notary who notarizes the signatures of the persons executing a contract abroad, pursuant to the 1961 Hague Convention, to which Mexico is a State Party. Although the Apostille certifies the authenticity of the signature, the capacity of the official, and the validity of the seal, the TCC did not treat these elements as sufficient to establish a certain date.
This thesis is not binding on other courts. Nonetheless, it is important to consider its content to prevent future tax contingencies.
The "certain date" requirement is a crucial evidentiary element that provides certainty regarding the moment a legal act becomes enforceable against third parties. In Mexico, certain date may be obtained through (i) registration, (ii) appearance before a notary or public attester, or (iii) the death of one of the signatories. The SCJN, in its binding precedent 2a./J. 161/2019 (Reg. 2021218), established that "certain date" is required for private documents submitted during tax audits.
Additionally, isolated thesis 2031684 (2026) considers that certain date is also required for private contracts executed abroad to have tax effects in Mexico. Although not mandatory, this thesis signals the position courts may adopt. Assessing this criterion helps prevent contingencies and ensures compliance.
Recommended actions
- Verify that any contract signed outside Mexico has a "certain date" before being submitted as evidence during a tax audit.
- Obtain signature acknowledgment before a foreign notary or elevate the document to a notarial instrument in the country of origin, and then obtain an Apostille. Once apostilled, present the document before a Mexican notary for certification or protocolization. The certification/protocolization date will be considered the certain date.
- For sensitive transactions (e.g., VAT refunds, material deductions, guarantees), ratify or protocolize the contract in Mexico and document the transaction's substance.
- Obtain an official Spanish translation by a court certified translator.
- Maintain supporting documentation evidencing the substance and materiality underlying the contract.
Conclusion
1) Effect of Foreign Notarial Acts and Apostille
When a contract is notarized abroad (e.g., signature acknowledgment or elevation to a notarial instrument) and apostilled, in our view the requirement of "appearance before a notary"—and thus certain date—may be satisfied provided that the apostilled document is subsequently taken before a Mexican notary for certification or protocolization. Based on the recent thesis, obtaining only the Apostille appears insufficient to establish certain date.
2) Tax Risks When No "Certain Date" Exists
Without a certain date, the tax authority may disregard the contract for VAT refunds, deductions, and materiality support. It is therefore advisable to reinforce foreign contracts with ratification/protocolization in Mexico and supplement them with operational and financial evidence.
To review your portfolio of international contracts, our team can assist you in designing best practices to mitigate risks in tax audits. We can also prepare customized checklists and defense files with comprehensive materiality documentation.
NOTICE
This alert is informational and does not constitute legal advice.