Almost any tutorial you find for setting up Google Ads Conversion Tracking via Google Tag Manager will tell you to also setup the Conversion Linker Tag. In Google Tag Manager itself, it will notify you to set up the Conversion Linker Tag when setting up a Google Ad Conversion Tracking Tag.

But why? What does the Conversion Linker Tag do that is so important?

The eli5 is that it helps your conversions to be measured more effectively. It utilizes first party cookies for your conversion tracking, which is important since most browsers are now blocking third-party cookies. Chrome is set to block third-party cookies by the end of 2024 in fact.

If you’re not using Google Tag Manager and instead are just installing the Google Tag (gtag.js) directly on to your website for conversion tracking purposes, it’ll be default use first party cookies unless you opt out, which obviously isn’t recommended as it will effect the accuracy of your conversion tracking.

You can technically do the same thing directly with the Google Tag but that would require you to edit the javascript and for most people it’s easier to just use Google Tag Manager and the Conversion Linker Tag.