Gemini now adds UTM parameters to outbound links, and Google has not documented when

Google Gemini has started adding UTM parameters to the links it sends people to. A Reddit user spotted the tags, and Google's John Mueller replied in the thread that he could see them too. Search Engine Journal reports that Google has not documented the change.

Why a tag matters when a referrer already existed

Mueller's first response was to ask whether Gemini already passes a referrer. It does. The problem is where that referrer survives.

• GA4 files a visit under Direct when it has no referrer and no UTM to tie it to a source, according to SEJ.

• In the thread, a user posting as CrawlWarden said the referrer mostly survives on desktop web only. They put pass-through from the Gemini mobile app at around 9 percent and said Android assistant invocations strip it entirely. These are one user's reported figures. Mueller asked for something he could reproduce and offered to forward it to the team.

• A UTM survives the in-app webview and shows up in raw server logs.

If those reports hold, desktop Gemini traffic was already measurable, and most mobile and assistant traffic was being counted as Direct.

What is still unknown

Google has not documented when the tag fires. SEJ points to ChatGPT as a comparison: it tags links in answers grounded in web sources and leaves answers drawn from training data untagged. SEJ guesses Gemini works the same way but says nobody knows until Google documents it.

SEJ also does not report the parameter values Gemini uses.

What to do with the first weeks of data

• Treat the early count as a floor. Any Gemini link that goes out without a tag still depends on the referrer, or lands in Direct.

• Read server logs as well as GA4. The UTM shows up in raw logs, so the two sources can be checked against each other.

• Pull the exact source and medium strings from your own logs before you write a GA4 channel rule for them.

• Watch Direct over the same period. Part of any jump in Gemini sessions will be visits moving out of Direct, which is a reporting change and does not mean Gemini is sending more people. Compare the two lines before you call it growth.

The useful output is a page list: which URLs Gemini actually sends people to. That tells you where you are being cited in a way that leads to a click.