What is a TC String?

A TC String, or Transparency and Consent String, is a machine-readable record used within IAB TCF to communicate a user’s privacy choices to participating vendors.

It can encode information about purposes, vendors, consent decisions, objections, and the CMP involved. A TC String does not prove by itself that consent was legally valid; it records and communicates the choices captured by the CMP.

The Court of Justice of the EU confirmed in 2024 that a TC String can constitute personal data when it can be linked to an identifiable user, such as through an IP address or another identifier.