UTM parameters: how to organise them so as not to corrupt your data
UTM parameters are the labels at the end of a link by which analytics recognises where a visitor came from. There are five: source, medium, campaign, term and content, with the first three carrying the main weight in the report. Without them, paid, organic and email traffic get mixed and every comparison between channels becomes a guess. There are three rules and they do not change: one naming convention, lower case everywhere and never on internal links. Capital letters create two rows for the same source, because the tools read them as different values. Breaking the third rule is the most common reason reports show impossible numbers, since an internal click starts a new session and attributes the sale to the wrong channel.
My name is Hristiyan Panov — a performance marketing consultant with over 5 years’ experience and over €2 000 000 I have managed advertising budgets for over 90 companies on Google and Meta. Below is a set of best practices and the mistakes I see most frequently.
What are the five parameters, and what does each one involve?
The parameters are attached after the question mark in the address and are separated by an ampersand. Their order in the address does not matter; the values do.
- utm_source — the specific platform: google, facebook, instagram, newsletter. This is where the name of the source goes, not its type.
- utm_medium — the type of traffic: cpc, email, social, referral, display. Analytics uses it to arrange visits into channel groups, so an invented value throws the campaign into “other”.
- utm_campaign — the name of the campaign, identical to the one in the platform. The match lets you reconcile the report against the ad account without matching things by hand.
- utm_content — the specific ad or variant, when you are testing. It separates two creatives within the same campaign.
- utm_term — the keyword used when manually tagging in Search.
The first three are compulsory. The other two are only used when you need to view them — otherwise, they just make the report more complicated.
An empty value is worse than a missing parameter: it is passed on, but in the report a row with no name appears that does not group with anything.
Why do capital letters spoil the report?
Because analytics treats them as different values. “Facebook”, “facebook” and “FaceBook” become three separate sources and the traffic is scattered between them. The same applies to medium — “CPC” and “cpc” fill two rows in the same report.
The effect is not cosmetic. A split source looks smaller than it is, and the comparison between channels loses its footing. Merging them afterwards is manual work on each report separately.
The rule is simple: everything in lower case, with a hyphen as a separator, no spaces and no Cyrillic characters.
Cyrillic is encoded in the address and shows up in the report as a string of characters that cannot be read. A space turns into a plus or a code and so produces yet another variant of the same value. The underscore works, but mixing it with the hyphen again gives two rows for the same thing.
Data already collected stays with the mixed-up case. The fix catches traffic from here on, which is why the convention is fixed before launch, not after the first report.
Why aren’t UTM parameters added to internal links?
This is because every UTM-tagged click starts a new session and attributes the visitor to the new source. Someone who came from Google and clicked on an internal banner with a UTM parameter is suddenly counted as a new visitor from the banner — and Google loses the conversion.
The result is a report in which in-site banners „drive“ sales, whilst paid channels appear weaker than they actually are. For in-site elements, different tracking mechanisms are used, not UTM.
Automatic or manual labelling in Google Ads?
Auto-tagging does the job and passes more data than UTM. It adds to the address a click identifier by which analytics pulls the campaign, group, keyword, match type and device — a level of detail that manual parameters do not cover.
Manual UTMs are added when the same data has to reach another system as well — for example a CRM or an email platform. These systems do not read the click identifier; they read what sits in the address as plain text and record it against the contact.
When you use both, make sure they are not duplicated — in a conflict the source data diverges between Google Ads and analytics. Which value wins is decided by a setting in analytics, not by the order of the parameters in the address.
The practical rule: if you add manual UTMs despite auto-tagging, write source=google and medium=cpc, so they match what auto-tagging would record. That way the two data sources do not diverge.
How should the convention be managed to prevent it from falling apart?
A single document accessible to anyone who creates links — including external contractors. It contains: the permitted values for ‘source’ and ‘medium’, the ‘campaign’ template, and who is responsible for new values.
The document works better as a table than as text. One column with the permitted value, one with an explanation of when it is used and one with an example of a ready link. That way the person in a hurry copies something ready-made instead of making it up.
The template for campaign benefits from a fixed order of parts — for example brand, campaign type, period — with the same separator. The fixed order makes the names sort in a sensible way in the report and lets you find a whole group of campaigns by the start of the name.
New values go through one person. If anyone can add them, the list grows faster than the report that has to serve it.
Without such a document, the agreement holds only until the first person who is in a hurry comes along.
How do you check that everything is working?
- In analytics, look at the list of sources for the last 30 days — every value written in two ways is a mistake. Also look at how much traffic landed as direct although it came from a campaign.
- Compare the number of sessions per channel with the clicks on the advertising platforms. A large discrepancy indicates lost tagging or re-routing, which skews the metrics.
- Check whether the redirects on the website preserve the parameters — this is a common and often unnoticed loss.
Redirects are tested by hand. You open the tagged link and look at the address after it loads: if the parameters are not there, analytics did not see them either. Go through the cases where the website redirects by itself — from http to https, from an address without www to one with www and the other way round.
Also check the link in the ad itself before it goes live. You copy the final address from the platform, open it in a browser and compare the values character by character against the convention. A wrong letter gives no error message; it simply creates a new source.
FAQ — Frequently Asked Questions about UTM parameters
Do UTMs harm SEO?
For external links — no. The problem arises with internal links, where duplicate URLs may be created. The canonical URL resolves this.
Can they be hidden from the address?
There are ways to wipe them once they have been read, but this adds complexity and risks data loss. It is usually not worth it.
How are emails labelled?
source = the name of the platform or list, medium = email, campaign = the specific mailing. It is important that this remains consistent every time.
What about the links on social media profiles?
It’s worth creating a separate label — medium = social, source = the specific network. Otherwise, organic social traffic gets mixed up with paid traffic.
How far back does the source go?
It depends on the attribution window and on cookies. Where the path to purchase is long, some of the initial source is lost — which is why UTMs are not a substitute an overview of performance.
Conclusion
UTM parameters are not a minor technical detail. They are the only thing that allows you to compare one channel with another — and when they are mixed up, any budgetary decision is based on a comparison that is inaccurate.
If your accounts do not match what you see on the platforms, start by arranging an independent review.
Request a quote for a digital audit →
Related articles: GA4 and Google Ads · MER · advertising account audit
