Start with meaning
The most common mistake is counting what share of the text a model wrote. The provision sets no percentage threshold, and content mixed with human-made material can still be synthetic content (European Commission guidelines, point 59). The deciding question is whether AI changed the meaning, the evidence or the apparent authenticity of the material. Under the guidelines, fixing typos and grammar and formatting are standard editing that does not trigger the marking duty in Article 50(2) (points 90 and 91), and compression and similar minor technical edits do not turn an image, audio or video into a deep fake (point 116), even if the tool passed over the whole material.
New argumentation, a cloned voice, an altered scene or a product shown with a feature it does not have is a different situation. Working categories that help start the analysis are: AI assisted, AI substantially modified, AI generated from scratch. They serve as an organising tool, while the wording of the law needs checking separately.
