Google announces 4 January 2024 start date for 3rd-party cookie phaseout

On 4 January a random global 1% sample of Chrome users will start seeing "Tracking Protection" enabled in Chrome, with 3rd-party cookies blocked by default.

Right now, Chrome has about a 63% browser share globally - billions of users.

Intent is said to be to enhance user privacy by decreasing the incidence of cross-website tracking.

Current longer-term plan is to complete rollout to all Chrome users by sometime in 2H2024. But meanwhile, it will be possible for users to re-enable 3rd-party cookies in some circumstances, until all the bugs are out.

Since July, Google has been permitting developers to use its Topics API to do live-traffic tests of a simulated cookieless Chrome for a limited number of their users.

The UK Competition and Markets Authority continues to keep an eye on this situation.

How smoothly will the transition go, and how will it affect ad spend? Stay tuned.