What is the construction log book?

The construction log book, bitácora de obra in Mexico, is the official technical and legal record of all significant events during the execution of a construction contract. It serves as the primary communication channel between the contracting authority and the contractor, and it constitutes full evidentiary proof before administrative and judicial authorities.

In Mexican public works, use of the log book is mandatory. In private construction it is not legally required, but it is highly recommended for both parties as the primary instrument of documentary protection.

There are two formats: the conventional log book, a physical folio-numbered book in original and two copies that must remain at the construction site, and the electronic log book. In federal public works, the electronic format is the rule.

The electronic log book: BEOP

The electronic system used in Mexican federal public works is the BESOP, Bitácora Electrónica y Seguimiento a Obra Pública, also referred to as BEOP in various agency guidelines. It is administered by the Secretaría Anticorrupción y Buen Gobierno and requires a valid advanced electronic signature (firma electrónica avanzada, FIEL) for every entry.

From April 17, 2025, use of the BEOP is mandatory for all new federal public works contracts. Contracts executed before that date continue under the rules in force at the time of execution.

For foreign contractors, this has a practical implication: every member of the project team authorized to make entries in the BEOP must hold a valid Mexican advanced electronic signature. Obtaining this credential takes time and requires registration with the tax authority (SAT). It should be treated as a pre-mobilization requirement, not an afterthought.

The LOPSRM (last amended November 14, 2025) establishes the obligation in Articles 46 (last paragraph) and 52 Bis. The LOPSRM Regulations (RLOPSRM) develop the framework in Articles 122 to 124.

Article 2, Section VIII of the RLOPSRM defines the log book as “the technical instrument that constitutes the means of communication between the parties that formalize contracts, in which the important matters and events that arise during the execution of the works are recorded.”

Article 122 establishes the obligation of use. Article 123 establishes the minimum rules of operation. Article 124 governs the physical log book as an exception.

The 2025 reforms did not eliminate the log book obligation or the BEOP system. They created the new digital procurement platform (Compras.mx, replacing CompraNet), reinforced end-to-end digital processing with electronic signatures, and introduced strategic dialogues and market research as legal requirements. The log book retains its legal nature, full evidentiary weight, and mandatory status.

What must be recorded

The log book is designed to capture the most significant events of contract execution. The following must be recorded:

  • Commencement of works
  • All matters related to progress valuations (estimaciones)
  • Extraordinary works
  • Authorized modifications to the executive project, construction procedures, quality aspects, and agreed execution programs
  • Cost adjustments
  • Schedule variations
  • Suspensions
  • Quality tests
  • Amendatory agreements (convenios modificatorios)
  • Key program milestones
  • Force majeure or acts of God affecting the execution schedule
  • Early termination, rescission, and contractual termination

This list is not exhaustive. Any event that has legal, economic, or technical significance for the contract should be recorded. The guiding principle is: if it is not in the log book, it effectively did not happen.

Minimum rules for entries

Article 123 of the RLOPSRM establishes the minimum operating rules:

The opening entry must record at minimum: the date of opening, general data of both parties, name and signature of authorized personnel, addresses and telephone numbers, specific contract data, and a descriptive scope of the works and site characteristics. It must also identify the technical personnel officially authorized as representatives of both the contracting authority and the contractor, and specify who is delegated the authority to make entries.

All subsequent entries must use the advanced electronic signature. Supporting documents, official letters, test reports, photographs, may be validated and attached to entries. The log book must be formally closed upon completion of the works.

When the physical log book is exceptionally authorized, it must remain at the construction site at all times. Removing it from the site is illegal and can generate administrative liability.

Evidentiary value

The log book has full evidentiary weight (prueba plena) under Mexican administrative and judicial law. There is a legal presumption that both parties have free access to it. A party that claims it was denied access must prove that denial with independent evidence, the mere assertion is insufficient.

This has direct consequences for foreign contractors. Events recorded by the supervision in the log book, delays attributed to the contractor, quality observations, instructions given, are presumed true unless the contractor demonstrates otherwise with its own log book entries or other documentary evidence. A contractor that does not make timely entries loses its ability to contradict the supervision’s version of events.

The evidentiary asymmetry is significant: the supervision typically makes entries systematically. Foreign project teams, unfamiliar with the instrument’s legal weight, often treat it as an administrative formality and make entries sporadically or not at all. By the time a dispute arises, the log book record is entirely one-sided.

What foreign contractors commonly get wrong

Not obtaining electronic signatures before mobilization. The FIEL registration process takes weeks. Teams that arrive on site without valid signatures cannot make legally valid entries from day one, creating a gap in the record that is difficult to remediate.

Treating the log book as an administrative formality. In Mexico, the log book is a legal instrument with the same evidentiary weight as a notarized document. Project managers and site engineers need to understand this from the first day on site.

Failing to record events attributable to the authority. Delays caused by incomplete project documentation, late delivery of the site, changes ordered by the supervision, quality test results, all of these must be recorded in the log book at the moment they occur, not reconstructed weeks later. A contemporaneous entry is vastly more valuable than a retrospective one.

Not responding to supervision entries. When the supervision records an observation, a delay notation, or a quality deficiency, the contractor must respond in the log book within the applicable deadline. Silence is interpreted as acceptance.

Removing the physical log book from the site. When the physical format is exceptionally authorized, the book must remain on site. Supervisors and authority representatives have the right to consult it at any time. Removing it creates administrative liability and undermines the contractor’s credibility in any subsequent dispute.

The log book and dispute strategy

In any construction dispute in Mexico, rescission proceedings, cost adjustment claims, extraordinary works recognition, schedule extension requests, the log book is the first document reviewed. Its entries either support or undermine every claim and every defense.

A well-maintained log book documents the causal chain between an event and its economic consequences: the authority issued a change instruction (entry by contractor), the supervision confirmed the instruction (entry by supervision), the change required additional resources (entry by contractor with supporting analysis), the contractor requested formal recognition (entry referencing the official letter). Without that chain, the claim has no evidentiary foundation.

Foreign contractors with experience in FIDIC-governed contracts are familiar with the notice and record-keeping requirements that protect claims. The BEOP serves an equivalent function in the Mexican framework, but with statutory backing and full evidentiary weight that contractual notice provisions do not always carry.

Dispute resolution

Disputes arising from construction contracts in federal public works are resolved before the Tribunal Federal de Justicia Administrativa. Conciliation before the Secretaría Anticorrupción y Buen Gobierno is available as a prior step. The log book is the primary evidence in both forums.

For contracts with PEMEX or CFE, jurisdiction falls to commercial courts. In private works, disputes are resolved in civil or commercial courts depending on the nature of the parties.

How Construbufete can assist

Construbufete advises foreign contractors on log book management and dispute documentation throughout the project lifecycle:

  • Pre-mobilization guidance on FIEL registration and BEOP access for foreign project teams
  • Training project managers and site engineers on the legal obligations and strategic use of the log book
  • Reviewing and structuring log book entries to build a claim-ready record
  • Responding to supervision entries that create adverse legal presumptions
  • Using the log book record to support cost adjustment claims, extraordinary works recognition, and schedule extension requests

If your team is mobilizing for a public works contract in Mexico or is already in execution, contact us before the first entry is made.

Frequently asked questions

Is the construction log book mandatory in Mexico? Yes, in federal public works. The LOPSRM (Arts. 46 and 52 Bis) and the RLOPSRM (Art. 122) establish the obligation. The electronic format (BEOP) is the rule from April 17, 2025. The physical format is an exception that requires authorization.

What is the BEOP? The BEOP, Bitácora Electrónica de Obra Pública, is the electronic log book system administered by the Secretaría Anticorrupción y Buen Gobierno. It requires a valid advanced electronic signature for every entry and provides a real-time, authenticated digital record of all significant events during contract execution.

What is the evidentiary value of the log book? Full evidentiary proof (prueba plena) before administrative and judicial authorities. There is a legal presumption that both parties have free access to it. Events not recorded in the log book are extremely difficult to prove in subsequent proceedings.

What changed with the 2025 LOPSRM reform regarding the log book? The obligation and the BEOP system were not eliminated. The main changes are the new digital procurement platform (Compras.mx replacing CompraNet), reinforced digitalization with electronic signatures, and the migration of supervisory and conciliation functions to the Secretaría Anticorrupción y Buen Gobierno.

Do foreign contractors need a Mexican electronic signature to use the BEOP? Yes. Every team member authorized to make entries must hold a valid Mexican advanced electronic signature (FIEL), issued by the SAT. This should be obtained before mobilization, as the process takes several weeks.

What happens if an event is not recorded in the log book? It is extremely difficult to prove in a subsequent dispute. Mexican courts and administrative tribunals apply a presumption that the log book is complete and accurate. An unrecorded event, even if it actually occurred, has no evidentiary foundation and will generally not be recognized in a claim or defense.