Seven UTM mistakes that quietly break your reports
None of these throw an error. That is what makes them expensive: the link works, the page loads, and the damage only shows up when someone asks you to explain the numbers.
1. Inconsistent capitalisation
Facebook and facebook become two rows. Split across a quarter, your
biggest channel looks like two medium ones.
Fix: lowercase everything, always, without exception.
2. Tagging your own internal links
This is the worst one. A UTM on an internal link starts a new session and overwrites the
original source. Someone who came from your newsletter, browsed, then clicked a tagged internal
banner is now attributed to your own site. The newsletter loses the conversion it earned.
Fix: only tag links that live somewhere other than your domain. To track
internal clicks, use event tracking.
3. Inventing utm_medium values
paid-fb, newsletter, ads — all reasonable to a human,
all invisible to channel grouping. They land in Other.
Fix: use the recognised values.
4. Confusing source and medium
utm_source=email&utm_medium=newsletter is backwards, and it is the most
common inversion there is. Source is the place; medium is the type.
Fix: utm_source=newsletter&utm_medium=email.
5. Putting personal data in a tag
An email address or customer ID in utm_term ends up in your analytics, your
logs, your referrer headers and any third-party script on the page. It is a privacy problem and,
depending on where your users are, a legal one.
Fix: never put anything in a UTM that identifies a person.
6. Losing tags through a redirect
Shorteners and redirect chains frequently drop query strings. The visitor lands, the tags do
not, and the session is filed as direct.
Fix: click your own link before sending it and check the final address bar.
7. Campaign names with no date
black-friday is unambiguous exactly once. The next year it merges with the
previous one and neither number means anything.
Fix: black-friday-2026.
Four of these seven — casing, spaces, accents and non-standard mediums — are caught automatically by the builder on this site, before the link ever reaches a campaign. The other three are habits.
Last reviewed 2026-08-13