The Transparency and Consent Framework (TCF) Version 2.3 was released on 19th June 2025, marking a significant advancement for resolving signalling ambiguity regarding Vendors’ disclosures. TCF v2.3 is already available, supported by updated specifications, implementation guidelines and the TCF Type Script Library iabtcf-es maintained by IAB Tech Lab. We recommend that TCF participants prepare, as the transition period is fast approaching and concludes on 28th February 2026.
Vendors may face uncertainty in specific scenarios where it’s unclear whether they were disclosed to the user.
This distinction is especially important when a vendor intends to process data for Special Purposes under Legitimate Interest (LI) but cannot infer from the signals contained in the TC String whether they were disclosed in the CMP UI to the user.
Although the signalling ambiguity has already been solved for Vendors that solely declare Special Purposes (see 2021 notification here), it had not been solved yet for Vendors that declare both Special Purpose(s) and Purpose(s) under LI.
Under 2.2, Vendors with such declarations could not distinguish between not having been disclosed in the CMP UI and the user having exercised their right to object when the LI bit for their Vendor IDs in the Vendor Legitimate Interest Section is set to 0. They therefore faced uncertainty as to whether they had established a legal basis for processing data in pursuit of Special Purposes under LI - which cannot be objected to within the Framework.
2.3 makes the previously optional disclosedVendors segment mandatory in order to resolve the ambiguity around the representation of LI in the TC string. This enhancement ensures that Vendors can always determine whether they were disclosed in the CMP UI.
For CMPs: CMPs must update their live installations to include the disclosedVendors segment in the TC String. As previously communicated, CMPs should not be required to re-surface the UI to accommodate this change.
CMPs that already made use of the previously optional disclosedVendors segment or kept record of which Vendors were disclosed at the time TC Strings were initially created may update existing TC Strings (please note that the lastUpdated field should not be changed in such a case).
However, CMPs that did not keep a record of which Vendors were disclosed at the time the TC String was initially created should wait for users to renew and/or change the choices they previously made to create a TC String that includes the disclosedVendors segment.
For Vendors: Vendors affected by the signalling ambiguity may already support the disclosedVendors segment as soon as they begin receiving TC Strings that include it.
Post 28 February 2026, all Vendors affected by the signalling ambiguity must recognise and act on the disclosedVendors segment appropriately.
Vendors must verify the bit for their Vendor ID in the disclosedVendors segment, where a 1 indicates they were disclosed, and a 0 indicates they were not disclosed, in order to determine whether they can process data in pursuit of Special Purposes.
Vendors that only declare Special Purposes shall also rely on the disclosedVendors segment to determine if the CMP has established transparency on their behalf instead of relying on the LI bit for their Vendor IDs in the Vendor Legitimate Interest Section.
For Publishers: Publishers that make use of a commercial CMP should not be affected by the transition, as there is no re-surfacing requirement associated with this update. Publishers operating their private CMP should refer to the corresponding guidance.
The TC String structure requires the mandatory Core String to precede all other segments, followed by the disclosedVendors and PublisherTC segments. Because both the disclosedVendors and PublisherTC segments include unique Segment IDs for identification, they may appear in any order after the Core String.
The transition period concludes on 28th February, 2026.
Starting 1st March, 2026:
For any questions about TCF 2.3, please reach out to tcf.compliance [at] iabeurope.eu.
