Which links need UTM tags? 4 in 10 would have been direct

What does a UTM tag do?

A UTM tag is a label at the end of a link that tells your analytics where the click came from. It looks like this: ?utm_source=newsletter&utm_medium=email&utm_campaign=weekly. Google says to always use utm_source, utm_medium and utm_campaign in its 2026 help pages.

Your analytics has two ways to learn where a visit came from. The first is the referrer: the address of the page the click came from, which the browser passes along. The second is the tag, which travels inside the link itself. When the browser passes a referrer, the visit gets a source even without a tag. When it passes none and the link has no tag, the visit has no source and lands in direct.

So a tag matters most in the places where the referrer gets lost. In our data, newsletter clicks never carried a referrer and most Instagram ad clicks did not, while clicks from Google results, Product Hunt and LinkedIn did. Private apps such as WhatsApp and Slack lose it too, as the 2023 test in our guide to high direct traffic shows.

Which links need a UTM tag?

Tag a link when you place it somewhere that does not pass a referrer, or when you need to tell two campaigns in the same place apart. Use this table for each place you put links.

Where the link goes	Passes a source on its own?	Tag it?
Newsletter or email	Rarely. On one site, 0 of 50 newsletter clicks had a referrer	Yes, every link
Social bio or link-in-bio page	Depends on the app and browser	Yes
DMs, WhatsApp, Slack, SMS	Often not, per the app test in our direct traffic guide	Yes
PDFs, slide decks, documents	Usually not; test it in step 2 below	Yes
Ads on social platforms	Depends on the app. On one site, 69% of Instagram ad clicks had no referrer, Facebook ad clicks 0%	Yes, so every ad click is named
Google Ads with auto-tagging on	Yes, through its own click ID	No, leave auto-tagging on
Public posts on the web, guest articles, directories	Usually	Optional. Tag if you want the campaign or post name
Answers in ChatGPT and other AI assistants	Sometimes. On one site, 10 of 31 ChatGPT visits had a referrer	You can't. The AI writes the link, so read the tag it adds
Links between your own pages	Not needed	Never

Which links should I never tag?

Never tag a link that goes from one page of your site to another. The tag replaces the real source of the visit with your own label, so the newsletter or search visit that brought the person in disappears. Loves Data lists "never use UTMs on internal links" as a best practice in its 2025 guide, because it splits one visit into several sources.

Leave Google Ads to its own tagging too. Auto-tagging adds a click ID called GCLID to each ad click, and Google turns it on by default for new accounts. The same 2026 help page says Google Analytics 4 gives auto-tagging priority over manual tags, so your own tags on those ads get overridden.

How do I check which of my links lose their source?

Run these five steps once. They tell you which places need tags and which already work.

1. List every place you put a link. Newsletter, email signature, each social bio, pinned posts, ads per platform, PDFs, partner pages. One row per place in a sheet.
2. Click each link yourself, on a phone and on a laptop. Open it from inside the app, the way a reader would. Then find your own visit in your analytics.
3. Read the referrer of that visit. If your tool shows a referrer such as l.instagram.com, that place passes a source on its own. If it shows none, that place sends direct traffic unless you tag it.
4. If you already tag some links, measure the gap. Filter visits that carry a campaign tag and count how many have no referrer, if your tool shows the referrer next to the campaign. A high share means the tag is the only thing naming those visits.
5. List every source value you see. Sort them alphabetically. Two spellings of the same place, such as Newsletter and newsletter, mean your reports are already split.

How many tagged visits would have been direct?

The tag was the only thing naming 365 of 936 tagged visits. Without it, those visits would have landed in direct. How we counted: the first page of every visit from 27 August to 3 November 2026, 2,537 visits in all. A visit counts as tagged when its link carried a source or campaign tag.

Where the tagged link was placed	Tagged visits	Share with no referrer
Newsletter (site B)	50	100%
ChatGPT answers, tag added by ChatGPT (site A)	21	100%
Instagram ads (site A)	417	69%
Threads posts (site A)	42	12%
Facebook ads (site A)	400	0%
Instagram, not an ad (site A)	6	0%
All tagged visits	936	39%

Two sites, 27 August to 3 November 2026. Where the link was placed decided whether the referrer survived.

The Instagram and Facebook ads ran under the same campaign ID on the same site, and nearly all clicks came from phones. Facebook passed a referrer every time. Instagram passed none on 7 in 10 clicks. Without the tag, most Instagram ad clicks would have joined direct, and the ad would have looked weaker than it was.

Tags covered only part of the gap. Across both sites, 1,374 visits arrived with no referrer, and a tag named 27% of them. The other 73% had no tag and no referrer, so they landed in direct with nothing to explain them.

Our own site is the untagged contrast. In the same window it had 195 visits, none tagged, and 76% of them arrived with no source at all.

Why does one app show up under three names?

One app shows up under several names when its visits get their source from different places: the referrer on some visits, and different tags on others. On site A, Threads sent 192 visits in our window under three source names.

Source name recorded	Where the name came from	Visits
l.threads.com	The referrer, no tag	150
threads	A tag on the link	37
ig_text_post_permalink	A tag on the link	5

A report sorted by source shows three rows, and the biggest says l.threads.com, a name nobody on the team chose. Google's 2026 default channel rules ignore case when they sort visits into channels, but its tagging guide says the values themselves are case sensitive, so one place typed two ways still shows as two sources. One naming sheet, used by everyone who shares links, prevents both problems.

How do I track visits from ChatGPT and other AI assistants?

You cannot tag these links, because the AI writes them, so read the tag it adds and the referrer together. ChatGPT normally adds utm_source=chatgpt.com to the links it cites, according to LLM Pulse's 2026 tracking.

On site A, ChatGPT sent 31 visits in our window. 21 of them arrived with no referrer, so ChatGPT's own tag was the only thing that named them. Without it, two in three ChatGPT visits would have counted as direct. Gemini sent one visit, and it carried a referrer. We saw no visits from Perplexity, Claude or Copilot on either site, so we cannot say yet how they pass a source.

That makes AI answers the one place where your numbers depend on a tag someone else controls. In October 2026 ChatGPT's tag briefly disappeared and those visits counted as direct; the person who first reported it later wrote that it was a bug. Seer Interactive notes in its 2026 update that when both the tag and the referrer are missing, the visit will likely appear as direct.

Three habits keep this visible as it grows:

1. Count it monthly. Filter source and referrer for chatgpt, perplexity, gemini, claude and copilot, and keep the count in a sheet. Small numbers today are your baseline for later.
2. Keep each tool's own name. Never merge them into one label such as ai. You want to see which assistant sends people.
3. Watch for a sudden drop. If ChatGPT visits fall and direct rises in the same week, check whether the tag stopped before you change anything else.

What naming sheet should my team use?

Use one sheet with fixed values for source and medium, and a fixed format for the campaign. Copy this one and change the rows to your own places.

Place	utm_source	utm_medium	utm_campaign
Newsletter	newsletter	email	issue name, for example 2026-11-weekly
LinkedIn post or bio	linkedin	social	post or bio
X post or bio	x	social	post or bio
Instagram bio	instagram	social	bio
Instagram or Facebook ad	instagram or facebook	paid_social	campaign name
PDF or slide deck	pdf	document	file name, for example pricing-guide
Partner or guest article	the partner's domain	referral	article name

Six rules keep it clean:

1. Lowercase only. Google's 2026 guide recommends it because values are case sensitive.
2. Use mediums the channel rules know. Google Analytics files a visit as Email when the medium is email, as Organic Social when it is social, and as Paid Social when the source is a social site and the medium starts with paid or contains cp. For places with no matching channel, such as PDFs, pick one medium and keep it.
3. One name per place, forever. Pick linkedin once. Never LinkedIn, li or linkedin.com later.
4. The campaign says what, the source says where. Never put the place in the campaign or the date in the source.
5. No spaces. Use hyphens.
6. One owner. One person adds new rows; everyone else copies from the sheet.

What did tagging change on one real site?

On site A, tags named 315 visits that had no referrer. Here is the method run on that site with its real numbers from 27 August to 3 November 2026.

1. Places with links. Instagram ads, Facebook ads, Threads posts, and answers from ChatGPT that mention the site.
2. What each place passes. Facebook ad clicks: a referrer on 400 of 400. Instagram ad clicks: no referrer on 289 of 417. Threads: a referrer on 187 of 192 visits. ChatGPT: no referrer on 21 of 31 visits.
3. What the tags saved. All 417 Instagram ad clicks carried the site's tag, so the 289 with no referrer were still named. The 21 ChatGPT visits with no referrer were named by the tag ChatGPT adds to its own links. That is 310 visits that would otherwise have been direct, plus 5 tagged Threads visits.
4. What still leaks. Threads posts carried a tag on only 42 of 192 visits, under two names. The site's Threads links kept their referrer, so few visits were lost, but the source is split three ways.
5. What to change. Keep the ad tags as they are. Add utm_source=threads&utm_medium=social to every Threads link the team posts, so all visits sit under one name. Leave the Facebook tags in place even though the referrer survives, because the tag carries the campaign ID.

The other 816 visits on site A had no tag and no referrer. Tagging cannot reach those until someone finds the links behind them, which is what step 1 is for.

When is tagging the wrong fix?

Tags fix one problem, links that lose their source, and they fall short in six situations.

• People forward the link. A tagged newsletter link pasted into a team chat still says newsletter, so the forward gets credited to the email.
• The tag gets stripped. Some redirects and link shorteners drop everything after the ?. Click your own shortened link once and check the landing address.
• Someone else writes the link. AI assistants add their own tags, so you cannot fix a missing one. The section on AI assistants above covers what to watch instead.
• Google Ads. Manual tags on Google Ads with auto-tagging on add nothing, as covered above.
• The source was never passed at all. Typed visits and bookmarks have no link to tag. Our direct traffic guide covers how to read what is left.
• Two sites are not a benchmark. Our shares come from two sites and one window. The 69% for Instagram ads describes those ads on those phones. Run step 2 on your own places before you trust any share, ours included.

What should I do this week?

Start with your newsletter or the email you send most. On site B every newsletter click arrived with no referrer, so if your email links have no tags, all of those visits are already in direct.

Then copy the naming sheet, add one row per place from step 1, and tag every link in the places that failed step 3. After 30 days, filter for visits with no referrer and see what share your tags now name.