Annex IV Technical Documentation: A Practical Guide

The technical documentation is a structured written record demonstrating that a high-risk AI system complies with the requirements of the EU AI Act. Think of it as the single source of truth about how your system was built, tested, governed and monitored.

Article 11 makes it mandatory: providers of high-risk systems must draw it up before the system is placed on the market or put into service and keep it up to date throughout the system's lifecycle. It underpins the conformity assessment and must be made available to national competent authorities on request. In short — no Annex IV file, no lawful high-risk system.

The obligation falls on providers of high-risk AI systems — those classified under Annex III or as safety components of regulated products. If you are unsure whether you qualify, work through the high-risk classification guide first.

Key timing points:

• The file must exist before the system is placed on the market or put into service.
• It must be kept current as the system evolves — new versions, retraining and material changes all require updates.
• For Annex III high-risk systems, the underlying obligations apply from 2 December 2027, but the documentation must be complete by the time you go to market — which in practice means building it during development, not after.

Annex IV sets out the required contents. A compliant technical file covers, at minimum:

• General description of the system — its intended purpose, the provider, versions, and how it interacts with hardware or other software.
• Development process and design choices — the methods and steps followed, key design decisions and the rationale behind them, plus any trade-offs made.
• System architecture and computational resources — how components fit together, and the resources used to develop, train, test and validate the system.
• Data requirements and governance — training, validation and testing datasets, their provenance, characteristics and the Article 10 data-governance measures applied.
• Human-oversight measures — the Article 14 mechanisms enabling people to understand, monitor and intervene in the system.
• The risk-management system — the Article 9 process, risks identified and the mitigations adopted.
• Validation and testing — accuracy, robustness and cybersecurity metrics, test procedures and results.
• Post-market monitoring — the plan for tracking the system's performance in real-world use after deployment.

These map directly onto the substantive obligations in Articles 9–15, which is why the technical file is best assembled alongside that work rather than reconstructed afterwards.

A workable approach turns Annex IV from a daunting report into a byproduct of good engineering:

• Use Annex IV as your table of contents. Create a document skeleton with one section per Annex IV heading from day one.
• Assign owners. Data governance sits with your data team, testing with QA, oversight with product — each populates their section as the work happens.
• Capture evidence continuously. Store dataset descriptions, test results, model cards and risk logs as you go; the file becomes an act of collation, not creation.
• Version it with the system. Tie each documentation revision to a system version so you can always show the file matching what shipped.
• Cross-reference, don't duplicate. Point to your Article 9 risk register and Article 10 data records rather than copying them, keeping a single source of truth.

Start by confirming you are actually in scope with the free risk checker, then build the skeleton and read the complete guide for how the technical file fits the wider programme.

Providers most often trip up on the same points:

• Leaving it to the end. Reconstructing a development history after the fact is painful and gap-ridden — document as you build.
• Treating it as static. The file must track the system; a document frozen at launch is non-compliant the moment you retrain or update.
• Thin data governance. Vague dataset descriptions are a frequent weak spot; provenance and representativeness need real detail.
• Ignoring post-market monitoring. The plan for watching real-world performance is part of Annex IV, not an optional extra.
• Confusing it with user instructions. The Annex IV file is internal evidence for regulators; the Article 13 instructions for use are a separate, deployer-facing document.