You will be able to set naming rules for UTM values so your reports group traffic the way you expect.
A month after Farah started tagging her links, she opened the traffic acquisition report and found her newsletter listed as four sources: "Newsletter", "newsletter", "email-newsletter" and "nl". She had tagged some links herself, her part-time assistant had tagged others, and her email tool had added its own tags. The campaign worked, but the report made it look like four small campaigns, none of them impressive.
Tags only help if everyone writes them the same way. UTM values are case-sensitive in GA4, which means values that differ only in capitalisation count as different values. "Email" and "email" are two different mediums, and "Instagram" and "instagram" are two different sources. GA4 files every visit under exactly what was typed. It does not merge differently spelled values on its own, and you can't merge them after the fact in the standard reports.
Spaces cause the same problem in a less obvious way. A space in a link gets converted to "%20" or to a plus sign, depending on where the link was built, so a value such as "work trousers" can show up as two different values. Punctuation and special characters also behave unpredictably in some apps. The fix is to lowercase every value, use hyphens instead of spaces, avoid punctuation and special characters, and allow only values from a fixed list.
Write down every source and medium your business is allowed to use, and treat any value not on the list as a mistake. Farah's sources are newsletter, instagram, facebook, tiktok, whatsapp, bazaar, partner-name (for any partner site), and google or meta for paid ads where those aren't tagged automatically. Her mediums are email, social, paid-social, cpc, referral and qr. She chose qr as the single value for print and QR codes.
When a new channel comes along, such as a podcast sponsorship, whoever adds it updates the list first and only then tags the link. This one rule prevents most of the mess.
GA4 sorts visits into default channel groups, such as Email, Organic Social, Paid Social, Paid Search, Referral and Direct. It decides the group mainly from the source and medium on each visit, following rules Google publishes in its GA4 help centre. A medium of "email" lands in Email. A medium of "social" usually lands in Organic Social. A medium of "cpc" with a search engine source lands in Paid Search.
GA4 can't place a made-up medium that its rules don't recognise, such as "newsletter-blast" or "ig-story", so those visits go to a group called Unassigned. Your channel report then shows a growing Unassigned row and an Email row that looks too small, even though the email worked.
Before you add any medium to your list, check Google's published default channel group definitions to see where it would land, and use the standard medium word wherever one fits. Google changes the definitions from time to time, so check them every time you add a medium. Don't rely on a list from memory, and that includes the examples above.
Some channels, such as Farah's printed QR codes, have no standard home. For these, make the choice on purpose. You can accept that the visits sit in Unassigned and filter for them by source. Or you can set up a custom channel group in GA4's admin settings, which is a group you define to give non-standard channels a home. What you want to avoid is visits landing in Unassigned by accident.
utm_campaign has the most freedom, which is why it gets messy fastest. Pick one pattern and stick to it. A good pattern starts with the date, because reports sort alphabetically and a date at the front puts your campaigns in time order. Farah uses year, month and a short theme, all lowercase with hyphens: 2026-11-work-trousers, 2026-12-year-end-sale, 2027-03-raya-edit. Vague names like "promo" or "sale2" tell you nothing a year later. A name like "Raya Sale FINAL v2" breaks three rules at once: it has capital letters, it has spaces, and there is no date at the front.
For utm_content, a simple description of the placement is enough, such as header-image, button, bio-link or story-1. Keep these values lowercase too.
The rules only work if the people tagging links can see them while they tag, and one page is enough. Farah's page has four parts:
allowed sources allowed mediums, with a note on which channel group each lands in the campaign name pattern, with two examples three finished links, built correctly
She pinned the page at the top of the shared folder and sent it to her assistant and to the freelancer who runs her ads.
Lesson 2.4, "Build your UTM tagging sheet", turns these rules into dropdowns so nobody has to remember them. Agree the rules page first, because a tagging sheet built without agreed rules just produces mistakes faster.
Now write the page for your own business. Use your real channels, cover the four parts above, and add a few example links that show the rules in action. Put the page where everyone who tags links will see it, and send it to each of them.
On one page, write your UTM rules: the allowed sources, the allowed mediums, a pattern for campaign names, and three example links.
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