California AI Transparency Act (SB 942, as amended by AB 853)

In short

Operative since 2 August 2026, the AI Transparency Act requires large generative AI providers (over one million monthly users, accessible in California) to give users a free public tool to check whether image, video or audio content was AI-generated, to embed a 'latent' machine-readable disclosure in all such outputs, and to offer an optional visible 'manifest' disclosure. Licensees of the system must keep those features or lose their licence. AB 853 delayed the original January 2026 start and added duties for large online platforms (2027) and capture devices (2028).

Key dates

1. Oct 13, 2025✓AB 853 signed: operative date moved from 1 Jan 2026 to 2 Aug 2026 and scope expanded
2. Aug 2, 2026✓Operative: covered providers must offer detection tool and latent/manifest disclosures
3. Jan 1, 2027UpcomingLarge online platforms must detect and display provenance data; hosting platforms may not knowingly offer non-compliant systems
4. Jan 1, 2028UpcomingCapture-device makers must enable provenance disclosures by default

What you have to do

• Provide a free, publicly accessible AI-detection tool that does not retain users' personal data beyond what is needed.
• Embed a latent (machine-readable) disclosure — provider name, system version, creation time — in every AI-generated image, video and audio file.
• Offer users an optional, hard-to-remove visible 'manifest' disclosure.
• Include disclosure-preservation terms in licences and revoke a licence within 96 hours if a licensee strips disclosures.
• If you run a large online platform, prepare to read and display provenance data by 1 January 2027.

Penalties

Civil penalty of $5,000 per violation, with each day of non-compliance a separate violation. Enforced by the Attorney General, county counsel or city attorneys; no private right of action.

Related lessons

• Level 1The world map of AI rules: EU, US patchwork, Canada, standards8 min
• Level 2Transparency and disclosure: telling people AI is involved7 min
• Level 5Staying current: key dates ahead and how to track change6 min

Industries where it matters

• 📣 Marketing, media & customer-facing AI