The EU AI Act just gave you a breach notification clock you didn’t know about

Most security teams already have a breach clock memorized. GDPR gives you 72 hours. SEC rules give public companies four business days after determining an incident is material. Those numbers get built into incident response runbooks, tabletop exercises and escalation paths, because the clock starts the moment the team confirms something happened.

Article 73 of the EU AI Act adds a third clock, and in my work advising enterprise clients on AI governance, I have yet to see one with a runbook for it.

The obligation took effect on August 2, and it did so alone. The EU’s Digital Omnibus on AI, in force since late July, pushed the rest of the Act’s high-risk enforcement wave — classification, conformity assessment, technical documentation — back to December 2027. Article 73 was not part of that reprieve, though the extra time elsewhere is worth using to get ready. It requires providers of high-risk AI systems to report serious incidents to national market surveillance authorities within 15 days by default, 10 days if a death is involved and just 2 days for incidents the Act classifies as widespread or as a serious disruption to critical infrastructure. Coverage of Article 73 so far has treated it as a legal filing requirement, handled through the same channel as a data protection filing. That framing misses what the obligation is. It is an incident response deadline, and it runs on a different trigger than the breach clocks most security teams already know.

A client once asked me, almost as an aside, whether their customer-facing AI tool would trigger a reporting duty if it simply gave someone bad information rather than getting hacked. At the time, the honest answer was probably not, under any framework they were tracking. Article 73 changes that, and most organizations building or buying AI for the EU market have not caught up yet.

What counts as a trigger here is broader than most teams expect

GDPR’s 72-hour clock starts when you become aware of a personal data breach. That is a bounded question. Did data leave the environment? Was it accessed without authorization? Article 73 asks something harder. The European Commission’s draft guidance takes the position that an indirect causal link between an AI system and a downstream harm is enough to trigger the reporting duty. Their example is a loan denial that traces back to a flawed AI credit assessment. The AI system does not cause harm the moment it produces the assessment, only once a human acts on it and denies the loan. The fundamental rights category requires the infringement to interfere with Charter-protected rights at scale, which is why the Commission illustrates that threshold with patterns, a recruitment tool that discriminates systematically or a credit system that categorically rejects an entire neighborhood. Under the Commission’s reading, once a pattern like that exists, the clock starts when the provider becomes aware of it, not when the system generated the output.

Here’s a plainer version of that pattern. A public benefits agency uses an AI system to match applicants against its records. A flaw in the matching logic occasionally conflates applicants, and over several weeks it happens to a run of different people, each flagged as already receiving the same benefit elsewhere and suspended. Nobody catches the pattern at the time, because each flag looks unremarkable on its own. Applicants don’t find out until their payments stop arriving, weeks after the first mismatch. The system never malfunctioned in any way security tooling would catch. It just produced bad matches until people started missing payments.

That is a different kind of determination than “Did we get breached?” It requires tracing a causal chain from a model output through a downstream decision to an actual harm, then judging how confident you are in that link before you are required to report it. Most incident response teams have a well-practiced instinct for confirming unauthorized access, but few have one for confirming that an AI system caused a harm that surfaced elsewhere in the business, days or weeks later. I have watched security leaders confidently answer, “Were we breached?” in minutes, then go quiet when asked, “Did our AI system cause this?” because nobody owns that second question yet.

Why this does not fit into an existing IR playbook

Most incident response programs are built around a single moment: detection. Something trips an alert, a SOC analyst confirms it and the clock starts. Article 73 incidents will not look like that at all. The AI system that produced the flawed output may show no signs of compromise. Nothing gets flagged by a SIEM. The first sign might come from a customer complaint, an internal audit finding or a pattern a compliance analyst notices months after the AI system made the decision.

That means the “becoming aware” clause in Article 73 is doing real work, and most organizations have not decided who is responsible for noticing. Is it the team monitoring the AI system’s technical performance, the business unit acting on its outputs, or whoever eventually hears the complaint? Under Article 73, the clock starts when any of them establishes, or suspects, the causal link, and 15 days is not a long runway if the first internal conversation about “is this our incident” does not happen until day six or seven. I have seen governance structures where a business unit head, a model risk team and security each assumed someone else owned this judgment call. In practice nobody did, and that gap is where a 15-day clock burns down to five.

Some security teams are already mapping agent governance to a maturity model, arguing that oversight must scale with autonomy, moving from agent identities that are barely inventoried toward ones that are bounded, monitored and revocable in real time. Article 73 raises the stakes on that model considerably. The less a human reviews an AI system’s output before it reaches a customer, the more likely a downstream harm surfaces without anyone watching for it in real time, which is exactly the blind spot Article 73 is designed to close.

What needs to change

A few additions belong in an existing incident response program before this becomes a live problem instead of a paper requirement.

First, a defined owner for the causal link determination. Data breach response usually has a clear owner: security confirms the technical facts, legal makes the materiality call. Article 73 needs an equivalent split: Someone technical enough to trace an AI system’s output to a downstream decision and someone with authority to make the reporting call once that link looks plausible rather than certain. In practice, I recommend naming this owner in the incident response plan, not leaving it to be sorted out during the first real incident, when the clock is already running.

Second, a lower bar for opening an investigation. If GDPR taught teams to investigate the moment unauthorized access is suspected, Article 73 requires investigating the moment a downstream harm is suspected to trace back to an AI system, when the system looks normal to security monitoring. That means feeding business unit complaints and customer escalations into the same triage process that currently only starts from technical alerts.

Third, a documented decision log for the indirect link judgment call. Given how broadly the Commission has defined what counts as reportable, organizations will make defensible calls not to report many ambiguous situations. Those decisions need to be documented with the reasoning behind them, the way a security team documents a false positive call, because a regulator revisiting that judgment months later will expect to see how it was made rather than take the outcome on faith.

Fourth, controls built into the AI system, not bolted on after the fact. A defined owner and a lower investigation bar help catch a problem once it surfaces, but neither reduces how often a flawed output reaches a customer first. Scoped credentials, tool allowlists and pre-action approval hooks cut down on how many incidents exist to report.

The AI Act’s high-risk obligations have absorbed most of the attention this year, because conformity assessments and technical documentation are heavy lifts with long lead times. Article 73 looks lighter by comparison, a reporting duty rather than a certification process. It is not lighter. It asks security and compliance teams to build a new kind of judgment into their incident response programs, on a clock as tight as anything GDPR or the SEC have required. Treat the deferral on the rest of the high-risk package as what it actually is, extra runway to build that judgment and name its owner, because the conformity paperwork still gives you months and Article 73 still gives you days.