Post-market monitoring
What it means
What is post-market monitoring under the EU AI Act?
Post-market monitoring is the EU AI Act duty on a provider to keep collecting and analysing real-world performance data on a high-risk AI system. It lasts as long as the system is in use. Monitoring catches problems that appear after launch, instead of assuming the original testing ruled them out.
Article 72 requires a documented monitoring system, sized to the technology and the risk of the specific system. It has to actively and systematically collect and analyse data on how the system performs once it is actually in use. Deployers feed into it directly, since Article 26 requires them to monitor the system on their end and report back to the provider. That way, the provider is not relying on its own visibility alone.
The monitoring plan is not a separate document. Article 72 makes it part of the system's technical documentation, built and updated alongside it, not added after a complaint. A pattern the monitoring finds also feeds the next duty in the chain. That duty is to decide whether what happened counts as a serious incident that requires a report.
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In practice
Why it comes up
Does anyone keep watching this system, or was it tested once and left alone? That is the specific question a customer’s security team or a regulator asks after any AI failure story in the press. A board hears it as reassurance that a problem would surface through a defined process rather than a customer complaint reaching the news first. Providers who can only describe pre-launch testing, and nothing after, usually have no answer.
What to do about it
Write the monitoring plan before launch, since a plan invented after a problem appears is not the same thing. In the plan, say what you measure, who reviews it and how often. Build a route for deployer-reported issues to reach the provider.
A monitoring system that never hears from the people using it day to day is monitoring very little. The Fractional CAIO Retainer I run keeps this review on a fixed schedule, not only when a customer complains.