Quick answer
Use UTM parameters on links that bring people to a site whose Google Analytics 4 property you control. A merchant can tag partner links to its own landing pages and compare source, medium and campaign in GA4. An affiliate sending visitors to someone else’s store usually cannot see that store’s UTM data; use the program’s affiliate ID, sub-ID or click report instead. Keep the referral identifier intact, use consistent UTM names, and test the final URL through any redirect before launch.
Most UTM advice for affiliates skips the ownership question. A tagged URL sends campaign information to the analytics property on the destination site. If you publish a link to a merchant’s checkout, you do not gain access to the merchant’s GA4 reports by adding utm_source. The merchant may value those tags, but your own commission record still comes from the affiliate program’s attribution system.
What do UTM parameters do?
UTM parameters are labels added to a destination URL. Google Analytics reads them when the visitor lands on a tagged page where its tag runs. Google recommends using utm_source, utm_medium and utm_campaign together; utm_content and utm_term add detail when needed. Its campaign URL guide also documents other supported fields, including utm_id and utm_source_platform. You do not have to fill every optional field.
| Parameter | What it answers | Example for a partner campaign |
|---|---|---|
utm_source |
Where did this visit come from? | partner_newsletter |
utm_medium |
What kind of placement sent it? | affiliate or email, according to your reporting convention |
utm_campaign |
Which initiative does it belong to? | autumn_demo |
utm_content |
Which creative or link placement? | comparison_table |
utm_term |
Which paid keyword, if applicable? | partner_software |
Do not use utm_term merely because the field exists. Do not invent dozens of sources for the same partner. GA4 treats differently capitalized values as different values, so a shared naming convention matters more than a clever label.
Merchant or affiliate? Use a different tracking plan
| You are… | Use UTMs for… | Use the affiliate system for… |
|---|---|---|
| The merchant | Comparing incoming visits and on-site events by partner, placement and campaign in your GA4 property. | Partner identity, attribution window, sale approval, refunds and commission. |
| The affiliate publisher | Tracking campaigns that bring people to your own site, where you control GA4. | Clicks on outbound offers and merchant-reported conversions, using approved affiliate links or sub-IDs. |
These records will not always match. A click can occur without a GA4 session if the visitor leaves before the tag loads, rejects analytics storage or the landing-page redirect drops the tags. A merchant may also attribute a later sale under different rules from GA4’s traffic reports. Compare records to investigate differences; do not call the GA4 session count a commission ledger.
How to build a tagged affiliate landing-page URL
- Start with the exact destination. Use the page where you want the buyer to land, not a generic homepage when a specific product or demo page exists.
- Preserve the partner identifier. If your program uses
ref=partner42, keep it. Do not replace it withutm_source; UTMs identify a campaign in analytics, while the referral parameter may decide who gets paid. - Add a consistent source, medium and campaign. For example:
https://example.com/demo/?ref=partner42&utm_source=partner_newsletter&utm_medium=affiliate&utm_campaign=autumn_demo. - Add content only when you will compare placements.
utm_content=header_linkandutm_content=footer_linkcan separate two links in the same email or page. They will not prove which message caused a later sale. - Use Google’s Campaign URL Builder or your own approved template. It helps construct the URL, but it cannot test your checkout integration or attribution rule.
- Open the link and inspect the final address. Confirm both the referral ID and UTM values survive redirects, consent flow and mobile browsing. Google’s click-versus-session troubleshooting guide identifies stripped URL parameters on redirects as a cause of missing campaign data.
When the destination already has a question mark, append new parameters with &; otherwise start with ?. Encode spaces and special characters. Treat the displayed example as a pattern, not as a link to paste without checking your program’s actual referral parameter.
Where to find the results in GA4
For the merchant’s property, open Reports → Acquisition → Traffic acquisition and use session source/medium or session campaign dimensions to compare incoming visits. Google’s Manual report documentation describes session manual source/medium and campaign dimensions for tagged traffic. If the report is customized, the exact navigation can differ. Filter by a campaign or partner source and compare the landing page and relevant key events.
GA4 shows the on-site events you configured; a tag alone does not create a paid-sale event. If checkout happens on another domain or sales close offline, arrange an approved connection from the order or CRM record to the original partner ID. Keep the program’s attribution and payout rules separate from the marketing report.
Five mistakes worth checking before publishing a link
- Tagging the wrong destination. UTMs on a merchant URL are visible to the merchant’s analytics, not automatically to an affiliate’s property.
- Replacing the referral ID with a UTM. A source label is not a commission instruction. Test attribution in the actual affiliate platform.
- Inconsistent names.
PartnerEmailandpartner_emailsplit reporting. Keep a short naming sheet. - Ignoring redirects. A short link is useful only if it keeps both campaign and referral parameters where they need to go.
- Tagging links within your own site. UTMs are intended to identify incoming campaigns. Use on-site event tracking for internal calls to action so campaign labels do not confuse acquisition analysis.
I would start with one partner, one destination and one test conversion. If that path works, expand the naming scheme. A spreadsheet with hundreds of meticulously named URLs will not rescue a missing referral ID or an unrecorded sale.
Frequently asked questions
What are the three UTM parameters to use on a campaign link?
Google recommends using utm_source, utm_medium and utm_campaign together. They identify where the visit came from, the type of placement and the campaign. Add utm_content or utm_term only when the extra detail serves a reporting question.
Can an affiliate see UTM data from a merchant’s website?
Usually not unless the merchant shares its analytics reports. UTMs are read by the destination site’s analytics property. An affiliate should use the approved affiliate dashboard, tracking ID or sub-ID for its own click and commission records.
Do UTM parameters track affiliate sales?
UTMs can label incoming traffic and configured on-site events in the merchant’s analytics. Commission attribution still depends on the affiliate program’s link or code, checkout integration, approval rules and refund handling.
Should I add UTMs to an existing affiliate link?
Only if the program permits extra parameters and they survive its redirects. Keep the original referral identifier intact, test the final landing URL and confirm a test conversion credits the right partner.
Where do I find UTM campaigns in GA4?
In the destination site’s GA4 property, use Traffic acquisition or the Manual report and select session manual source/medium or campaign dimensions. The report shows tagged visits and configured events, not an automatic affiliate payout ledger.
Why do GA4 sessions and affiliate clicks differ?
A click is recorded at a different stage from an analytics session. Redirects, consent choices, a visitor leaving before the tag loads, and different counting rules can create gaps. Check the final URL and the program’s event logs before assuming a tracking failure.
