Third-Party Cookies in Chrome: What Google Decided

In December 2023, Google announced a plan to retire third-party cookies for every Chrome user during the last six months of 2024. That plan depended on the UK Competition and Markets Authority (CMA) having no remaining competition concerns.

On April 23, 2024, Google changed course. It said it would not complete the phase-out in the window it had set for late 2024. Two reasons were given. Industry, regulators and developers had given feedback that pulls in different directions. And the CMA needed time to review evidence, including industry test results the regulator had asked for by the end of June.

Google said it hopes to settle the matter with the CMA and the UK Information Commissioner's Office this year. If they agree, it expects to start the phase-out early next year. As of this writing, that is a hope and not a date.

Sources: Google, "The next step toward phasing out third-party cookies in Chrome" (December 14, 2023); Privacy Sandbox, "Update on the plan for phase-out of third-party cookies on Chrome" (April 23, 2024)

For most people, Chrome still allows third-party cookies by default. But a test is running. On January 4, 2024, Chrome began restricting third-party cookies by default for 1% of Chrome users worldwide. The feature is called Tracking Protection.

Chrome picks those users at random and shows them a notice. When a site tries to use a third-party cookie, an eye icon appears in the address bar. If a page breaks, the user can switch the cookies back on for that site for a while.

Anyone can also block third-party cookies today in Chrome's cookie settings. Developers can try the restriction themselves in Chrome 121 or later by turning on a test flag. Chrome's developer tools also show warnings when a page depends on cross-site cookies.

Sources: Google, "The next step toward phasing out third-party cookies in Chrome" (December 14, 2023); Privacy Sandbox, "January 2024. Prepare for the third-party cookie phaseout"

Chrome is late to this change, not early. Other browsers moved first.

• Firefox. Since September 2019, Firefox has blocked known third-party tracking cookies by default, using a published list of trackers. In 2023, Mozilla began rolling out Total Cookie Protection by default to more users. It keeps each site's cookies in a separate "cookie jar" so trackers cannot follow a person from site to site.
• Safari. In March 2020, Apple's WebKit team announced full third-party cookie blocking by default in Safari. It called Safari the first mainstream browser to do so.

The result is that third-party cookies already fail for many of your visitors. Chrome's choice affects how large that group becomes, not whether it exists.

Sources: Mozilla, "Today's Firefox Blocks Third-Party Tracking Cookies and Cryptomining by Default" (September 3, 2019); Mozilla, "Firefox rolls out Total Cookie Protection by default to more users worldwide" (April 11, 2023); WebKit, "Full Third-Party Cookie Blocking and More" (March 24, 2020)

The CMA has a say because Google has tied its Chrome timeline to the regulator's review of the Privacy Sandbox, the set of tools meant to replace third-party cookies. Both Google updates cited here say so. The CMA asked market participants for test evidence by the end of June 2024, so the review was still open as this guide went live.

That is why the decision is a delay and not a cancellation. Google's own words still describe a plan to phase out the cookies. They do not describe a plan to keep them for good.

Sources: Google, "The next step toward phasing out third-party cookies in Chrome" (December 14, 2023); Privacy Sandbox, "Update on the plan for phase-out of third-party cookies on Chrome" (April 23, 2024)

The sources above report what Google, Mozilla and Apple did. The advice below is our editors' view of how a B2B team can use that information.

• List what depends on cross-site cookies. Ask each ad, analytics and retargeting vendor how its tools work when third-party cookies are blocked. Write down the answers.
• Test now. Turn on Chrome's test flag, browse your own site and forms, and check the developer tools for blocked-cookie errors. Watch for broken logins, embedded forms and booking widgets.
• Build first-party data. Newsletter sign-ups, gated guides and account logins give you contact with buyers that does not depend on another company's cookie. Ask for consent and say plainly how you use the data.
• Read Safari and Firefox numbers separately. Those visitors have lived without third-party cookies for years. Your reports for them show what the future looks like in Chrome.
• Do not set budgets around a single date. Google has already moved this timeline once this year. Plan so that your results hold up whether Chrome changes in a few months or later.

B2B buying cycles are long and involve many people. Cookie-based tracking has always followed one browser, not one buying committee. Moving toward first-party data and clear consent fits how B2B sales work anyway.

Sources: Privacy Sandbox, "January 2024. Prepare for the third-party cookie phaseout." The recommendations are the editors' own judgment.

1. Google, "The next step toward phasing out third-party cookies in Chrome," December 14, 2023. blog.google
2. Privacy Sandbox, "Update on the plan for phase-out of third-party cookies on Chrome," April 23, 2024. privacysandbox.com
3. Privacy Sandbox, "January 2024. Prepare for the third-party cookie phaseout." developers.google.com
4. Mozilla, "Today's Firefox Blocks Third-Party Tracking Cookies and Cryptomining by Default," September 3, 2019. blog.mozilla.org
5. Mozilla, "Firefox rolls out Total Cookie Protection by default to more users worldwide," April 11, 2023. blog.mozilla.org
6. WebKit, "Full Third-Party Cookie Blocking and More," March 24, 2020. webkit.org