- Article 50(2) requires providers of generative AI to mark synthetic outputs in a machine-readable format, detectable as artificially generated or manipulated.
- The obligation applies from 2 August 2026. A provisional May 2026 agreement (the "AI Omnibus") would give systems already on the market until 2 December 2026 to meet the machine-readable part. Treat both as live and re-verify.
- Scope is broad. It is not limited to high-risk AI. It reaches any business using generative AI to produce content.
- The legal bar is that the technique be "effective, interoperable, robust, and reliable." A watermark hidden inside the pixels fades silently under ordinary edits, so watermark-only marking is hard to defend against that bar.
- Cryptographically signed provenance (C2PA / Content Credentials) is the machine-readable, tamper-evident layer that answers the reliability test, with watermarking as one corroborating signal.
Article 50 is the transparency article of the EU AI Act. It is short, it is not restricted to the high-risk tier everyone spent 2024 worrying about, and its marking obligation lands on a much wider set of products than most teams assume. If you ship a feature that generates synthetic media, this is the clause that now expects a machine, not just a person, to be able to tell.
What Article 50 asks for
The part that matters for content marking is Article 50(2). It puts the obligation on providers of generative AI systems, including general-purpose systems: the outputs they produce (synthetic audio, image, video, or text) must be marked in a machine-readable format and detectable as artificially generated or manipulated. A separate obligation, in Article 50(4), sits on deployers who publish deepfakes or AI-generated text on matters of public interest, and is about human-facing disclosure. The two are often conflated. This piece is about the first one: the machine-readable mark on the output itself. The practical guide from the EU Artificial Intelligence Act project and the European Commission's own transparency FAQ are the primary references.
The dates that matter
Three dates are worth writing down, and one caveat is worth writing in bold.
- 2 August 2026: Article 50 transparency obligations become applicable.
- 2 December 2026: under a provisional May 2026 agreement often called the "AI Omnibus," generative-AI systems already on the market before the applicability date would get until here to satisfy the machine-readable marking requirement specifically.
- Mid-2026: a Code of Practice on marking and labelling, which the Commission began drafting in late 2025, is expected to land in a final form and give concrete, testable guidance on acceptable techniques.
Caveat, in bold because it is the important one: the Omnibus was provisional at the time of writing and regulatory dates in this file can move. Verify the current status against the official sources before you plan a release around any of them. Nothing here is legal advice.
The bar you actually have to clear
Article 50(2) does not just say "mark it." It says the technical solution must be "effective, interoperable, robust, and reliable, taking into account the state of the art." Those four words are the whole test, and they are where a marking strategy either holds up or quietly does not:
- Effective: a machine can actually detect the mark.
- Interoperable: it works across tools and platforms, not only inside your own product.
- Robust: it survives ordinary handling of the file.
- Reliable: you can trust the answer it gives.
The last two are the trap for anyone planning to lean on a hidden watermark. An in-band watermark, the family Google DeepMind's SynthID belongs to, hides a recoverable signal inside the pixels or tokens. It survives a screenshot. It does not reliably survive someone editing the file: a frequency-notch filter, a denoise pass, a re-encode, or a paraphrase can attenuate the signal while the content still looks and reads fine. Worse, the failure is silent. A stripped mark announces nothing, so a marking method can pass on an untouched file and then fail invisibly after one routine re-save. That is a hard thing to call "reliable."
You do not have to take that on faith. Our interactive lab injects a synthetic watermark and lets you watch its detection score collapse under exactly these edits, and the companion white paper, Why AI watermarks break, works through the mechanism.
Your machine-readable options
There are two families of machine-readable marking, and they fail in opposite ways.
| Approach | What it is | Where it struggles |
|---|---|---|
| In-band watermark | Hides a recoverable signal inside the media (SynthID and relatives) | Fades silently under ordinary edits; detection is a probability, and absence proves nothing |
| Signed provenance (C2PA) | Attaches cryptographically signed metadata bound to the asset (Content Credentials) | A recipient has to check it, and the credential can be stripped, but stripping or tampering is detectable rather than silent |
The key difference for the reliability bar: a watermark fails quietly, and a signed credential fails loudly. When tampering breaks a C2PA signature, "invalid" and "no credential" become explicit, checkable states rather than a probability that faded. That auditability is exactly what a regulator, or your own compliance team, needs to stand behind a claim.
What a defensible marking posture looks like
The pragmatic answer is not to pick one. It is to layer, so that no single technique carries the whole load:
- Content Credentials (C2PA) as the backbone. Cryptographically signed, tamper-evident provenance is the part you can audit, and it is an open, interoperable standard (currently version 2.4) with a live conformance program.
- Watermarking as one corroborating signal. It gives population-scale coverage even on assets that lose their metadata, as long as you treat a low or absent score as inconclusive, not as proof.
- Human-readable disclosure on top. Where a person interacts with the AI or the content, plain labeling covers the transparency-to-people obligations that machine marking does not.
Document the lawful basis and retention for anything you log along the way. Again, not legal advice: this is an engineering-readiness view, not a substitute for counsel at the point you formalize a compliance claim.
A short readiness checklist
- Inventory every surface where your product generates synthetic content.
- Choose your machine-readable method. Prefer signed provenance for the reliability bar; add watermarking for coverage.
- Test robustness honestly: does your mark survive a re-save, a crop, a re-encode, a paraphrase? You can feel that failure mode in the lab in about a minute.
- Add human-facing disclosure wherever people meet AI content.
- Track the Code of Practice and the Omnibus timeline, and re-verify the dates before you commit a release.
Frequently asked questions
When does Article 50 apply?
Article 50 transparency obligations apply from 2 August 2026. A provisional May 2026 agreement (the AI Omnibus) would give systems already on the market until 2 December 2026 to meet the machine-readable marking part of Article 50(2). Both are moving targets. Verify current status against official sources.
Does Article 50 only apply to high-risk AI?
No. The transparency obligations are not restricted to the high-risk tier. They reach the situations the Article covers, which in practice includes any business using generative AI to produce synthetic images, text, audio, or video.
Does watermarking satisfy the machine-readable marking requirement?
It can contribute, but a watermark-only strategy is hard to defend against the requirement that the technique be effective, interoperable, robust, and reliable. In-band watermarks fade silently under ordinary edits, so signed provenance (C2PA / Content Credentials) is the tamper-evident layer that answers the reliability test, with watermarking as one corroborating signal.
Is this legal advice?
No. This is an engineering-readiness explainer, not legal advice, and the regulatory dates here can change. Confirm the current position with the official EU sources and your own counsel before relying on it.