EU AI Act Article 50: Who Must Disclose What, and How to Mark AI Output

What Article 50 requires

Article 50 requires that people know when they are dealing with AI. It does that through four duties: disclose an AI interaction, mark synthetic output so machines can detect it, notify people exposed to emotion or biometric systems, and disclose deep fakes and AI-written public-interest text.

The provision is short, and that brevity is what makes it hard. It sets outcomes rather than methods, leaves its key qualifier “obvious” undefined, and splits the four duties across two different operator roles without saying so explicitly. Most compliance failures here are not failures of intent. They are a provider assuming the publisher will label the output, or a publisher assuming the model vendor already did.

Two further paragraphs govern how all four are performed. Article 50(5) requires the information to be given clearly and distinguishably, at the latest at the time of the first interaction or exposure, and to conform to the applicable accessibility requirements. Article 50(6) confirms that none of this displaces the Chapter III high-risk requirements or any other transparency obligation in Union or national law.

Who owes which duty

Providers owe the interaction notice and the machine-readable marking duty. Deployers owe the emotion and biometric notice and the deep fake disclosure. One organization can be both, and then owes all four.

The split follows the logic of the Regulation as a whole: duties that require changing how a system is built sit with the provider, and duties that depend on how a system is used sit with the deployer. A model vendor cannot know whether its image generator will be used for a satirical cartoon or a fabricated political endorsement, so the disclosure duty for that output cannot sensibly sit with the vendor. Equally, a publisher cannot retrofit a durable watermark into content the model has already emitted, so the marking duty cannot sit with the publisher.

Each duty in detail

Each duty below sets out what triggers it, what satisfies it, and the carve-outs written into the paragraph itself.

Marking synthetic content in practice

Article 50(2) sets an outcome, not a method: the mark must be machine-readable, and the output detectable as artificially generated or manipulated, using solutions that are effective, interoperable, robust and reliable as far as is technically feasible.

That wording does real work. “As far as is technically feasible” is a moving standard tied to the acknowledged state of the art as reflected in relevant technical standards, which means what was defensible in 2026 will not be defensible in 2029. It also means no single technique discharges the duty, because each of the three available approaches fails in a different way.

Why layering is the defensible position

A signed provenance manifest carries by far the richest information: the tool, the model, the edit history, cryptographically bound and verifiable. It is also the most fragile. Take a screenshot, or upload through a pipeline that re-encodes, and the manifest is gone. An embedded signal survives that handling much better but carries almost no information beyond “synthetic”, and it needs a detector, which means an ecosystem question rather than an engineering one. File metadata is trivial to write and trivial to strip.

Applying all three costs little more than applying one, and it is the combination that lets you argue you did what was technically feasible. Document that reasoning at the time. When a market surveillance authority asks why you chose a given approach, a contemporaneous note comparing the options is worth considerably more than a retrospective justification.

Where the marking duty stops

Article 50(2) does not apply where the AI system performs an assistive function for standard editing, or does not substantially alter the input data supplied by the deployer or its semantics. This is the carve-out that keeps ordinary tooling out of scope: autocorrect, denoise, color grading, a grammar suggestion. The test is substantial alteration of the data or its meaning, so the boundary is a question about your specific feature, not about your product category. Generative fill that invents new objects in a photograph is not standard editing, even though it lives in an editing tool.

When “obvious” removes the duty

The Article 50(1) disclosure duty falls away only where the AI nature of the interaction is obvious to a reasonably well-informed, observant and circumspect person, taking the circumstances and context of use into account.

This is an objective test measured against a notional careful user, not against your most sophisticated customer and not against your own team. Three features of the wording matter in practice.

• Context is part of the test. The same assistant may be obvious inside a developer console and non-obvious in a consumer messaging app, because the population interacting with it differs.
• Design choices can destroy the exemption. A human name, a photographic avatar, first-person phrasing and simulated typing latency all push an interface away from obvious. If you have invested in making a bot feel human, you have argued yourself out of the carve-out.
• Obviousness is not durable. Conversations get forwarded, embedded and resumed days later. A cue that was obvious at the start of a session may not be present at the point a decision is taken.

The practical answer is that the exemption is rarely worth relying on. A one-line disclosure at the top of a conversation is cheap; a dispute about whether your interface was obvious is not.

How it sits with other duties

Article 50 is additive. Article 50(6) states expressly that it does not affect the Chapter III high-risk requirements and is without prejudice to other transparency obligations in Union or national law.

An implementation checklist

Work role by role. Establish whether you are provider, deployer or both for each system, then discharge only the duties that attach to that role.

Next: see how Article 50 fits the wider schedule in every EU AI Act compliance deadline, or read the provision itself at Article 50.