Google’s Additional Consent technical specification

In this article

• Components of the Additional Consent
• The "Additional Consent" (AC) string format
• CMPs that support Additional Consent
• Extension to the CMP API
• How should an AC string be stored?
• How to pass the AC string through the digital advertising chain
• Related Resources

This document describes Google’s Additional Consent technical specification, which is intended only for use alongside IAB Europe’s Transparency & Consent Framework (TCF) v2 to send transparency and/or consent signals to vendors who are not yet registered on the IAB Europe Global Vendor List (GVL). This specification allows publishers, Consent Management Platforms (CMPs), and partners to gather and propagate additional consent—alongside their TCF implementation—for companies that are not yet registered with the IAB Europe Global Vendor List but are on Google's Ad Tech Partners (ATP) list.

Components of Additional Consent

Additional consent consists of a lightweight addtl_consent string (AC string), which contains a list of consented and/or disclosed Google ad technology partners (ATPs) that are not registered with the IAB’s Global Vendor List (GVL).

How to generate an "Additional Consent" version 2 (ACv2) string

What information is stored in an AC string?

An AC string contains the following components:

• Part 1: The specification version number. The current version is "2"

• Part 2: The separator symbol "~"

• Part 3: A dot-separated list of user-consented Google Ad Tech Provider (ATP) IDs. Example: "1.35.41.101"

• Part 4: A separator symbol "~"

• Part 5: "dv." followed by a dot-separated list of disclosed Google Ad Tech Provider (ATP) IDs. Example: "dv.9.21.81"

  Vendors included in Part 3 should not be included in Part 5 to reduce string length.

AC string examples

If ATP vendors with IDs 1, 2, 3, 4, and 10 are disclosed to the user:

• …and the user has seen the CMP message disclosing these vendors but has not yet made a decision of whether to consent: the corresponding ACv2 string would be 2~~dv.1.2.3.4.10.

• …and the user has provided consent to all vendors: the corresponding ACv2 string would be 2~1.2.3.4.10~dv.. Note that the "." after dv is optional in this case only, so 2~1.2.3.4.10~dv is also an accepted ACv2 string.

• …and the user has rejected consent for all vendors, the corresponding ACv2 string should indicate that all vendors have been disclosed but none are consented. The corresponding ACv2 string would be 2~~dv.1.2.3.4.10.
• …and the user has provided consent for vendors 1 and 10 but rejected consent for all other vendors, the corresponding ACv2 string would be 2~1.10~dv.2.3.4.

Who should create an AC string?

An AC string may only be created by an IAB Europe TCF-registered CMP using its assigned CMP ID number in accordance with the IAB Policies. Vendors or any other third-party service partners must not create AC strings themselves.

Where are the Google ATPs be published?

Google maintains a list of ad technology partners not registered with the IAB and their IDs at the following location:

https://storage.googleapis.com/tcfac/additional-consent-providers.csv

When should an AC string be created?

In all cases, an AC string may only be created where the publisher is in compliance with Google’s EU User Consent Policy.

Consented vendors should only be included when the user has given legally valid consent to:

1. the use of cookies or other local storage where legally required; and

2. the collection, sharing, and use of personal data for personalization of ads by an ATP, as well as complying with all other terms of Google’s EU User Consent Policy.

Disclosed vendors should only be included when appropriate transparency is provided to users on the identity of each ATP, including linking to the ATP’s privacy policy as provided in Google’s ATP list. Vendors included in the consented vendor list do not need to also be included in the disclosed vendor list.

An AC string must only be created as a supplemental string to the TC string, and not in place of the TC string. Google will not process the request and will discard the AC string on a request received by Google if a TC string is not available for the same request.

CMPs implementing this spec must make sure that the AC string they create contains only IDs from the published Google ATP file (that is, non-GVL vendors). When Google receives a TC string, it will check the version of the GVL that is listed in that TC string. If that version of the GVL has a registration for a vendor, the TC string controls for that vendor and any AC string entries for that vendor will be ignored. In this circumstance, Google reserves the right to remove such "duplicate" entries from the AC string and pass on correspondingly modified AC string alongside the TC string. Vendors other than Google may not modify the AC string.

Are Additional Consent v1 strings still supported?

Additional Consent v2 has been the standard Additional Consent version since December 2023. Additional Consent strings generated based on the v1 specification will continue to be supported. However, such strings can't indicate if transparency is established for an ATP. To support use cases that do not require consent, CMPs should migrate to the v2 specification.