What? The IAB has published a minor update to the TCF guidelines. The change affects the ‘disclosed vendors’ (disclosedVendors) section in the TC string. ‘Disclosed Vendors’ refers to the vendors displayed to the user in the CMP. This information is now mandatory.
Why? The legal basis of ‘legitimate interest’ for ‘special purposes’ is to be strengthened. In our opinion, the IAB wants to use the mandatory disclosure to strengthen accountability and dispel doubts about the lawfulness of the processing. Since the IAB now itself relies on this legal basis for the processing of the TC string (‘special purpose 3’), this is also essential for the IAB itself.
When?
1) The updated technical specifications and the TCF JS Library were published on July 3, 2025.
2) All participants are required to fully support the writing, reading, and processing of the ‘Disclosed Vendors’ section by February 28, 2026. After this date, any TC string without the ‘Disclosed Vendors’ section will be considered non-compliant with the TCF.