How should an agency standardise UTM tagging?

What actually goes wrong with UTM tags?

Spelling, almost always. One person writes Facebook, another writes facebook, a third writes fb, and analytics treats them as three unrelated sources. Nothing errors; the report simply understates each one.

The second failure is medium being used as a free text field. Once medium contains campaign names or dates, the one dimension designed to group channels stops grouping anything.

What should each parameter hold?

Keep the roles strict and the vocabulary short.

• Source — where the link was published. A platform name, lowercase, from a fixed list.
• Medium — the kind of traffic. A handful of values, agreed once. Organic social, paid social, email, referral.
• Campaign — the initiative, not the individual post.
• Content — the individual post or variant, which is where specifics belong.

Why does lowercase matter so much?

Because analytics platforms treat values case sensitively in most reports. Facebook and facebook are two rows that never recombine, and nobody notices until a quarterly number looks wrong.

Enforce lowercase in the convention itself rather than relying on care. A link builder that only offers approved values removes the problem entirely.

How do you keep a convention alive?

Make the correct path the easy one. A shared link builder — even a spreadsheet with dropdowns — will be used; a document describing the rules will not.

Review the source and medium lists quarterly. If a value appears once and never again, it was invented at build time, which means the convention is not being followed and the report is quietly degrading.