What the regulation says
Article 13 of the Mexican pesticide registration regulation covers applicants who lack physicochemical, physical, toxicological, ecotoxicological or environmental fate data. They can ask COFEPRIS to use the data their supplier filed for a product that is already registered. The application must include the document showing the supplier authorised that access, and the data must correspond to the same product.
If the supplier is not itself entitled to use that information, the letter must be signed by whoever is entitled, either in favour of the supplier or directly in favour of the applicant. If the supplier is abroad and has never registered the product in Mexico, the applicant must file the physicochemical, physical, toxicological, ecotoxicological and environmental fate data itself, together with the document showing the supplier authorised its use.
Biological efficacy follows its own rule: the applicant files the SADER notice acknowledging access to the efficacy information and its technical opinion (article 13, last paragraph; article 12, section II, item d).
When it shortens the dossier
For formulated products, the full technical package is not required when the applicant or its supplier already holds a registration of the technical, or of a formulation of the same active ingredient, with the same active ingredient manufacturer. The application cites that registration number and complies with article 13 (article 12, section II, last paragraph).
The simplification notice published in the DOF on 22 October 2025 states, procedure by procedure, which studies a letter of access and use of information exempts:
| Procedure (code) | Studies exempted with a letter of access |
|---|---|
| Technical registration (COFEPRIS-06-001) | Physicochemical, toxicological, ecotoxicological and environmental fate |
| Formulated registration (COFEPRIS-06-002) | Physical properties and toxicological studies |
| Technical amendment (COFEPRIS-06-016) | Physical properties and toxicological studies |
| Adding a manufacturer, formulator or supplier (COFEPRIS-06-017) | Toxicological, ecotoxicological, environmental fate, physicochemical and physical properties |
| Renewal (COFEPRIS-06-031) | Toxicological, ecotoxicological, environmental fate, physicochemical and physical properties |
For renewals, article 23 Bis 1 also asks for the original supplier letter and the letter of access; the 2025 notice lists the supplier letter and treats the letter of access as the ground for exempting studies.
When a letter does not help
A letter gives access to someone else's data for the same product. If your technical comes from a different manufacturer than the one in the existing registration, you need technical equivalence against the reference profile (or the full technical package). We explain it in the technical equivalence guide.
The 2026 amendment adds a second limit. Since the amendment published on 24 April 2026, the safety and efficacy data of a “new agricultural chemical product” are protected for ten years from its first registration in Mexico (article 13 Bis). Within those ten years, using that information requires the express consent of its holder (article 10).
Drafting it so it holds
The regulation does not prescribe a template. What it does require is a document that proves the authorisation and that the information is the same as the product applied for (article 13). In practice, a letter that names the holder, the registration number, the product and its composition as registered, the beneficiary and the scope of the access leaves the evaluator little to question.
If you manufacture outside Mexico and have no company there, decide early whose name goes on the registration that the letters will point to. See how registration holding works.
Would it be a bad idea to check, before anyone signs, whether the registration your letter points to really covers your active ingredient manufacturer? Send us the product list and we reply in writing.
Frequently asked questions
Does a letter of access replace all studies in Mexico?
No. It covers the studies the regulation and the 2025 simplification notice list for each procedure, and only for information that is the same as the product applied for (article 13).
Can a letter of access cover a technical from a different manufacturer?
No. The exemption in article 12, section II requires the same active ingredient manufacturer as the registration cited. A different manufacturer goes through technical equivalence.
Is efficacy covered by the same letter?
No. Biological efficacy requires a SADER notice acknowledging access to the efficacy information and its technical opinion (article 13, last paragraph).
Sources
- Mexican Pesticide Registration Regulation (Reglamento en Materia de Registros, Autorizaciones de Importación y Exportación y Certificados de Exportación de Plaguicidas, Nutrientes Vegetales y Sustancias y Materiales Tóxicos o Peligrosos), as amended in the DOF, 13 February 2014: articles 12 (section II), 13 and 23 Bis 1.
- Simplification notice for COFEPRIS procedures (Acuerdo por el que se establecen acciones de simplificación…), DOF 22 October 2025, article third.
- Decree amending the pesticide registration regulation, DOF 24 April 2026 (article 10 and article 13 Bis).
Informational guide based on public regulations in force on the date shown. It does not replace a review of your dossier.
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