What goes into utm_source for TikTok and LinkedIn Ads — Google's official list has the answer

Many operators set utm_source=tiktok-ads or utm_source=linkedin-ads on their TikTok Ads / LinkedIn Ads URLs. Naming a media + -ads is intuitive — it makes "TikTok ad" or "LinkedIn ad" explicit in the data.

But GA4's (Google Analytics 4) officially distributed "Default Channel Group Source Categories" file[1] contains only 2 rows for TikTok and 3 rows for LinkedIn, and neither tiktok-ads nor linkedin-ads is in those 5 rows. Any value outside this list is judged by GA4 as "not from a social site" and silently drops out of the Paid Social report.

This article works through what to put into utm_source for TikTok and LinkedIn Ads, using the 5 rows from the official list GA4 actually evaluates. Then it goes one step further — into the question that always remains after the naming is fixed: "so which of the two actually sold more?" Naming is the entrance to fixing classification; the material for deciding where to put your budget comes after that.

Key takeaways#

1. Use tiktok or linkedin (lowercase shortform). These are the official entries — shortest match, lowest typo risk
2. tiktok-ads / tiktok_ads / linkedin-ads / linkedin_ads are not registered. They fall out of Paid Social into the (other) channel
3. Short URLs and mobile subdomains are not registered either. vt.tiktok.com / m.tiktok.com / m.linkedin.com won't get SOCIAL judgment (the one exception is LinkedIn's official shortlink lnkd.in)
4. But even with correct naming, "which of the two sold more" never shows up in GA4's standard reports. How to compare real revenue by channel, once traffic is classified correctly, is covered in the second half

1. How GA4 decides "Paid Social"#

Bottom line: A visit is Paid Social only when utm_source is on the official list AND utm_medium matches the cpc-style regex.

GA4's default channel group classifies every visit by reading utm_source × utm_medium[2]. Paid Social requires both of these conditions to hold simultaneously:

• utm_source must match a value registered in GA4's "social sites regex list"
• utm_medium must match the regex ^(.*cp.*|ppc|retargeting|paid.*)$[2]

The "social sites regex list" itself is distributed by Google as an .xlsx file (actually delivered as PDF), and it contains 819 source names and category labels[1]. Whether TikTok or LinkedIn is judged as Paid Social depends not on industry convention or tool recommendations — it depends on this single file.

The utm_medium side and its recommended value are fully unpacked in the sister article What goes into utm_medium for Meta Ads. This article focuses on the utm_source side, reading the TikTok and LinkedIn rows.

2. TikTok and LinkedIn entries actually in the official list#

Bottom line: Only 2 rows for TikTok and 3 for LinkedIn are registered — no variant (-ads / _ads / mobile subdomains) is on the list.

Out of the 819 entries on the official list, the rows for TikTok and LinkedIn are exactly the 5 shown below — organized across platform, registered value, official category, and note.

Three facts stand out from these 5 rows:

1. All 5 rows fall under SOURCE_CATEGORY_SOCIAL. The Source-side condition for Paid Social is met only when one of these 5 rows is matched exactly
2. TikTok has 2 rows, LinkedIn has 3. Only LinkedIn includes its official shortlink lnkd.in, which makes it easier to capture mobile referrals
3. No variants exist at all. tiktok-ads / tiktok_ads / TikTok-Ads / linkedin-ads / linkedin_ads / m.tiktok.com / vt.tiktok.com / m.linkedin.com — none of these match any of the 5 rows

The name "social sites list" might suggest that all variants of TikTok or LinkedIn are covered. In reality, only one lowercase shortform and one or two domain forms are present.

Because Google may update the official .xlsx at any time, when you reference this for production work, download a fresh copy each time instead of relying on the values captured at this article's publication (May 2026 release, June 2026 latest check).

3. Four utm_source failure modes#

Bottom line: Variants, mixed case, and short/mobile subdomains all fall out of Paid Social, scattering revenue across stray rows and breaking the aggregate.

What happens when you put a value that is not in those 5 rows? Here are 4 patterns.

Failure 1: tiktok-ads / linkedin-ads disappear from Paid Social#

Media name + -ads reads naturally to internal operators, but neither value is registered in the official list. As a result, TikTok Ad traffic shows up as a standalone "source/medium = tiktok-ads / cpc" row and never enters the Paid Social aggregate. Monthly reports show "Paid Social revenue dropped sharply" when, in reality, the classification has simply detached. linkedin-ads produces the same failure.

Failure 2: TikTok / LinkedIn (mixed case) splits one campaign into two rows#

GA4 stores utm_source values case-sensitively, as-is. If utm_source=tiktok and utm_source=TikTok coexist inside the same campaign, the report splits into two rows. Only the tiktok side passes Paid Social judgment; the TikTok side does not match the lowercase tiktok entry and falls into Referral or (other). With multiple operators running spreadsheet-based naming, 3–4 variants will line up and break aggregation.

Failure 3: vt.tiktok.com / m.tiktok.com / m.linkedin.com (shortlinks and mobile) are not judged as SOCIAL#

TikTok's in-app share feature generates vt.tiktok.com referrals, and TikTok mobile web sends m.tiktok.com as the host. LinkedIn mobile arrives via m.linkedin.com. None of these match any of the 5 rows. Even for non-ad organic traffic, those visits stack into Referral / (other) and never get categorized as Organic Social or Paid Social. Only LinkedIn's official shortlink lnkd.in is registered, so internal shares and shortened URLs via LinkedIn do get SOCIAL recognition.

Failure 4: tiktok_ads / linkedin_ads (underscore-separated) also disappear#

Same as the hyphen-separated form, the underscore-separated forms are not in the official list either. On the utm_medium side, values like paid_social / paid-social get caught by the paid.* regex and Paid Social judgment passes; on the utm_source side, the list is exact-match only, so similar-looking strings fall into (other) immediately.

4. Recommended format and verification steps#

Bottom line: Use the lowercase shortform tiktok / linkedin — the shortest exact match on the official list, with near-zero typo risk.

The recommended format, derived by reverse-reading the 5 official rows, is:

# TikTok Ads
utm_source=tiktok
utm_medium=cpc
utm_campaign={{campaign.name}}
utm_content={{ad.name}}
utm_id={{campaign.id}}

# LinkedIn Ads
utm_source=linkedin
utm_medium=cpc
utm_campaign={{campaign.name}}
utm_content={{ad.name}}
utm_id={{campaign.id}}

Three reasons to recommend utm_source=tiktok / linkedin:

• Shortest exact match on the official list: 5 rows total, this is the shortest form. Near-zero typo risk
• Reads cleanly across the org: the media name itself, no decoding needed when someone reads the report
• Consistent with other media: parallel to facebook for Meta Ads and google for Google Ads

What happens by utm_source value, summarized in one image:

The before/after checks are 2 items:

1. Pre-launch URL preview: In TikTok Ads Manager / LinkedIn Campaign Manager, open the URL preview from the ad edit screen and verify utm_source=tiktok or utm_source=linkedin is rendered as-is
2. Post-launch GA4 Realtime: Within 30 minutes of launch, in "Realtime" → "Source/Medium", verify the visit shows up as tiktok / cpc or linkedin / cpc. If it shows tiktok-ads / cpc or (direct) / (none), the parameters didn't arrive — or the UTM naming doesn't match the official list

RevenueScope solution

Bottom line: Fixing the naming gets you as far as "classified correctly." But "how much that correctly-classified channel actually sold" never comes out of GA4's standard reports, no matter how perfect your naming. That's where RevenueScope begins.

Even if you match the naming perfectly to the 5-row official list and drive spelling variance to zero, GA4's standard reports show you sessions and conversions — no further. "For the same 100 sessions, how much did TikTok vs LinkedIn earn per session (RPS)? Which has the higher AOV and purchase rate?" — lining those up side by side on bot-excluded clean numbers, the comparison you need to decide which one to fund, sits beyond correct naming and is never filled by the naming work alone.

RevenueScope automatically normalizes utm spelling variants (even if past periods ran as tiktok-ads or TikTok, they merge into one channel). But normalization is only the preprocessing. The core is being able to compare, on bot-excluded clean numbers, real revenue, RPS (Revenue Per Session), AOV, and purchase rate by channel on one screen. Instead of figures each platform claims separately, it uses your own revenue as a common reference so you can decide whether TikTok or LinkedIn deserves the next budget.

Alongside aligning the naming to the official list, read which of the two channels sold more — by revenue. That's the next step toward turning UTM tagging into a budget decision instead of leaving it set-and-forget.

Conclusion: only 5 rows are written in the official list#

Across social and operator blogs, you'll find factions debating "for TikTok Ads, tiktok-ads is the cleanest naming" or "for LinkedIn, linkedin_ads". But what GA4 actually references during Paid Social judgment is TikTok 2 rows + LinkedIn 3 rows = 5 rows on the official list[1]. tiktok-ads and linkedin-ads are not in those 5 rows. tiktok and linkedin are. That's the only fact.

Once the naming collapses to one row on the official list, traffic gets classified correctly. But all you learn there is the fact that it was "classified correctly" — "so which of TikTok and LinkedIn earned more per session" never comes out of GA4's standard reports. If fixing the naming is this article's goal, deciding which one to fund by revenue is the next one.

Related articles in /en/news:

• UTM: 4 patterns breaking GA4 channel grouping
• What goes into utm_medium for Meta Ads
• What goes into utm_source for Meta Ads
• Why "(direct) / (none)" grows in GA4 and how to handle it
• The last-click trap distorting your ad budget calls
• GA4 isn't a tool for reading revenue — the attribution blind spot

References#

1. Google « GA4 Default Channel Group Source Categories (official distribution file · 819 entries) » Last checked May 2026
2. Google Analytics Help « [GA4] Default channel group » May 2026