EU AI Act Annex IV specifies the technical documentation that providers of high-risk AI systems must maintain under Article 11. It is the single most important document in the EU AI Act for governance documentation practitioners — and it is both less prescriptive than practitioners working from secondary commentary expect, and more demanding in ways that secondary commentary rarely emphasizes.
Annex IV is organized into ten content categories. Rather than prescribing document formats, it specifies information categories that the technical documentation must contain. A careful reading reveals that Annex IV requires: (1) a general description of the AI system including its intended purpose and the natural persons or groups it is intended to be used by; (2) a detailed description of the system's components and development process; (3) information about the training, validation, and testing data; (4) information about the system's performance on relevant populations; (5) a risk management system description; (6) changes to the system and its versions; (7) standards applied; (8) conformity assessment and EU declaration of conformity; (9) post-market monitoring plan; and (10) any other relevant information.
Category 10 — "any other relevant information" — is frequently overlooked in secondary commentary but is substantively important: it is the catch-all through which implementing acts and national market surveillance authority guidance will specify additional documentation requirements that Annex IV does not explicitly enumerate.
First, the training data documentation requirement is more demanding than most commentary suggests. Annex IV requires information about the characteristics of the data used for training — including the data acquisition and selection methodology, cleaning processes, labeling methods, and how training data was evaluated for relevance, representativeness, and possible biases. This is not metadata documentation; it is a substantive description of data governance practices that most organizations have not documented at the required level of specificity.
Second, the performance documentation requirement must address performance across "relevant population groups." For systems used in consequential decisions affecting people, this requires documentation of how performance was evaluated across demographic groups — and what differences in performance across groups were identified and addressed. This connects directly to fairness and bias analysis documentation that many organizations are beginning to produce but few have integrated into their technical documentation in Annex IV–compliant form.
Third, the post-market monitoring plan is a separate document requirement, not a section of the technical documentation. Annex IV references the post-market monitoring plan as a document that must exist and be described in the technical documentation — but the plan itself must be maintained as an operational governance document, updated as the system evolves in deployment. Organizations that treat post-market monitoring as a technical documentation section rather than as an operational governance program will find the distinction surfacing as a finding in conformity assessment.
The most efficient approach to EU AI Act Annex IV technical documentation is to design the document structure around the ten content categories, produce primary documentation for each category at the level of specificity the category requires, and integrate supplementary documentation (model cards, data sheets, risk registers) as referenced exhibits rather than inline content. This produces technical documentation that is navigable for market surveillance authority review and maintainable as the system evolves. Documentation that treats Annex IV as a checklist rather than a content architecture specification will require structural redesign when conformity assessment review reveals gaps in how the content categories interact.