Conversion tracking & GTM setup

What usually goes wrong

Problems I find in most accounts I inherit

Duplicate conversions

The same purchase counted by two tags, inflating ROAS and hiding the true cost per sale.

Conversions firing on page load

A "thank you" page tag that fires on every visit or refresh, not just a genuine completed action.

Cross-domain journeys losing their source

A visitor moves from your site to a checkout on a different domain and shows up as direct traffic, wiping out the ad that actually won them.

Offline sales never making it back

Phone bookings, showroom sales or sales-assisted deals that never get matched back to the ad click that started them.

Consent mode misconfigured

Cookie banners built without consent mode wired in properly, so a large share of conversions are silently modelled or lost.

Value not passed through

Every conversion logged as "1", regardless of whether the order was £20 or £2,000 — so value-based bidding has nothing to bid on.

What's included

What actually gets set up

✓ Full GTM container audit Every tag, trigger and variable reviewed — duplicates and dead tags removed, naming made consistent so the next person can understand it too.
✓ GA4 conversion events rebuilt properly Key events set up against genuine, verified actions, with the right parameters attached — not just the default event names left as-is.
✓ Enhanced conversions & value passing Hashed customer data and real order values fed back to Google and Meta, so value-based bidding has something worth bidding on.
✓ Offline conversion imports Phone leads, CRM-qualified deals and sales-assisted purchases matched back to the click that started them.
✓ Server-side tagging, where it earns its keep A server container to recover data lost to ad blockers and browser tracking limits — only where the account is large enough to justify the extra moving part.
✓ Consent mode, done properly Configured so the cookie banner and your ad platforms actually agree with each other, minimising modelled data gaps.
✓ A written record of what changed What was broken, what was fixed, and how to verify it — so it isn't a black box only I understand.

How it runs

Three stages, in order

Audit

Read-only access to your GTM container, GA4 property and ad accounts. I test every conversion event by hand — placing real orders and submitting real forms where needed — rather than trusting what the dashboard reports.

Fix

Changes go through a staging environment first wherever the site setup allows it. Nothing goes live untested, because broken tracking is worse than no tracking — it's confidently wrong.

Verify & document

Every event checked again after launch using GTM's preview mode and GA4's DebugView, then written up in plain English so you or anyone else can see exactly what's being measured and why.

Questions people ask

Before we start

Is this a one-off project or ongoing?

Usually a one-off project to fix and document what's there, with a light ongoing check as part of a media management retainer if we work together on the ads too. It doesn't have to lead to anything further.

Do I need to already be running ads with you?

No. Plenty of people bring me in just for the tracking, sometimes because an existing agency isn't the right one to mark its own homework.

What access do you need?

Editor access to GTM and GA4, and read access to whichever ad platforms you're running. If a developer needs to publish container changes on your side, I'll hand over exactly what to publish rather than needing their time for anything else.

Will this break anything that currently works?

That's what the staging and verification steps are for. Nothing replaces a working conversion action until its replacement has been tested and confirmed to fire correctly.

How do you charge for this?

A flat fee, scoped after a short look at what's currently in place — the size of the job depends far more on how tangled the existing setup is than on the size of the business.

Fixing the numbers before anyone optimises against them