But there’s a more pressing deadline looming that advertisers need to prepare for: SameSite. Beginning on Feb. 4, Chrome will stop supporting cross-site third-party cookie sharing by default.
Third-party cookies that aren’t secure – as in, accessed over HTTPS – and also properly labeled using the SameSite attribute, will no longer be readable across sites.
Google has framed the SameSite change as primarily a security measure to protect against cross-site request forgery attacks.
But in light of Chrome’s more recent announcement, it’s clear that requiring SameSite flags are also a precursor to the demise of third-party cookies.