What is the addtl_consent cookie?
addtl_consent is part of the technical infrastructure of the IAB Transparency and Consent Framework (TCF) v2.x, the standard used by most digital advertising platforms to record user consent. It does not belong to a single provider — it is set by the CMP script installed on a site, particularly when that site uses Google's "Additional Consent" mode for ad technology vendors that are not registered on the IAB Global Vendor List (GVL).
The cookie usually appears as soon as a visitor interacts with the consent banner (accepts, rejects, or customizes their choices), and is stored alongside the main TCF consent cookie, euconsent-v2.
What data it stores
addtl_consent stores a string that encodes the list of additional vendors (identified by numeric IDs) for which the visitor has given or withheld consent. The exact value differs from one visitor to another depending on the choices made, and its length can vary.
The data stays stored locally in the browser cookie and is read by the advertising scripts on the site to decide which targeting technologies may run; it can also be sent to the listed vendors as proof of the consent given.
What it is used for
The cookie serves a purely functional purpose: it lets advertising scripts and the CMP platform remember the visitor's choices regarding ad technology vendors that are not formally registered in IAB TCF but are used by Google or other advertising partners. This avoids showing the consent banner repeatedly and ensures the visitor's preferences are respected on every page load.
Does it require consent?
Because it only stores the visitor's own consent choice and is not itself used for tracking or advertising, addtl_consent is classified by CookieFix as strictly necessary. Strictly necessary cookies do not require prior consent under the ePrivacy Directive 2002/58/EC (transposed into Romanian law via Law 506/2004, enforced by ANSPDCP), but they must still be disclosed in the site's cookie policy, with a clear purpose and duration.
Site owners should check how their CMP is configured (especially whether it enables Google's Additional Consent mode) and list this cookie in the cookie policy alongside the platform's other technical cookies.
How to block or delete addtl_consent
Visitors can delete or block addtl_consent from their browser settings (Chrome, Firefox, Edge, Safari), in the per-site cookie management section. Deleting it resets the choices made for additional vendors, and the consent banner will appear again on the next visit.
- For site owners, a platform like CookieFix automatically classifies addtl_consent as necessary and exempts it from pre-consent blocking, since it is part of the consent mechanism itself.
- Statistics and marketing scripts, by contrast, stay automatically blocked until the visitor gives consent.
Frequently asked questions
It's a technical cookie from the IAB Transparency and Consent Framework that stores a visitor's consent for advertising vendors not on the IAB Global Vendor List, used mainly alongside Google's Additional Consent mode.
It's set by the CMP (consent management platform) script running on the website, not by a single specific provider, when a visitor interacts with the cookie banner.
No, it's classified as strictly necessary because it only stores the visitor's own consent choice, though it still must be listed in the site's cookie policy.
It typically lasts around 1 year, though the exact duration and value can vary depending on the CMP configuration used on the site.