Tracking tags in practice: testing, consent and avoiding duplicates

The other articles in Tracking and tags cover installing each platform's tag. This one covers what tends to go wrong once they're in, and how to check your tracking really works. It's based on setting up tracking on our own website.

Load each tag once, from one place

A tag can reach your site in several ways: pasted into your site's custom code, through Google Tag Manager, or through your website builder's built-in integration (Webflow, Wix, Squarespace and Shopify all have one). Use one route for each tag.

If the same tag loads twice:

• conversions can be counted twice
• one copy may ignore your cookie banner
• it gets very hard to work out what's firing and why

Watch out for website builder integrations. Fields such as "Google tag ID" or "Meta Pixel ID" in your site settings usually load the tag on every page straight away, before the visitor has chosen anything in your cookie banner. If you already load your tags another way, leave those fields empty.

Keep tags behind cookie consent

In the UK and EU, advertising and analytics tags generally need consent before they run (see Tags and cookie consent). A safe set-up has:

• a cookie banner with clear Accept and Reject options
• Google Consent Mode defaults set to "denied" before any Google tag loads
• advertising tags (Google Ads, Meta, TikTok, Microsoft and LinkedIn) that only load after the visitor accepts advertising cookies

Two side effects to expect:

• Google says your tag isn't installed. Google's site scanner and some set-up screens visit your site without accepting cookies, so they never see the tag. It doesn't mean it's broken. Test it yourself instead (see below).
• Platforms report fewer conversions than really happened. Anyone who rejects cookies isn't tracked. Your form submissions or sales records are the true total.

Tracking a form with no thank-you page

Many forms, including most Webflow, Wix and Squarespace forms, show a thank-you message on the same page instead of loading a new one. That matters, because a common way to track a lead is to count visits to a thank-you page. With no thank-you page, that conversion never fires.

You have two options:

1. Fire an event when the form succeeds. A small script watches for the thank-you message to appear, then tells each platform: a Google Ads conversion event, a Meta Lead event, and a dataLayer event for Tag Manager. This is what we use.
2. Send people to a real thank-you page after they submit, and track visits to it. Simpler, but anyone can land on that page directly, so keep it out of your navigation and search results.

Fire on the success message, not the button click. A click on Submit also happens when the form fails, for example when a required field is empty.

Don't paste Google's code as it is

When you create a conversion action, Google shows you two pieces of code: the Google tag, for every page, and an event snippet, for the conversion. Pasted straight into your site, both run before the visitor has made a cookie choice. Take the important parts instead, your tag ID (such as AW-123456789) and the conversion label after the slash, and add them through your consent-aware set-up or Tag Manager.

Avoid counting a conversion twice

Google's tag has settings that can detect form submissions automatically. If you also send your own conversion event, one form can register twice. Check in Tag Assistant: if you see two conversion hits for one submission, turn off the automatic detection or remove your own event. Setting the conversion action's count to One also stops a single ad click being counted twice (see Conversion actions: what they are and how to set them up).

Testing with Google Tag Assistant

1. Close any Google Ads, Analytics or Tag Manager tabs. Tag Assistant can pick up Google's own tags from those pages, which makes it look as if your site has extra tags.
2. Go to tagassistant.google.com, click Add domain and enter the exact page you're testing, such as your landing page.
3. Reject cookies first. You should see no Google tags. If you do, something is loading without consent.
4. Then accept cookies. You may need to clear your cookie choice to see the banner again. Your tags should now appear, such as your Tag Manager container and your Google Ads tag.
5. Submit the form in the connected tab. Look for your conversion event in the timeline on the left, then a Conversion hit on your Google Ads tag.
6. Delete the test submission afterwards.

For Meta, use the Test events tab in Events Manager. For TikTok, use the TikTok Pixel Helper browser extension.

Making sense of what you see

• Tags you don't recognise: check which page Tag Assistant says they came from. Tags listed under a Google Ads or Analytics page belong to Google, not your site.
• Page View and Remarketing hits: normal. That's your Google Ads tag recording the visit.
• A GA4 ID (starting G-) listed as a destination of your Google Ads tag: your Google tag has an Analytics property linked to it. Check it's your company's property, not someone's personal one.
• "No conversions recorded" warnings: these clear once real conversions come through, which can take a day or so after set-up.

A quick checklist

• Each tag loads once, from one place.
• Nothing loads before cookie consent.
• Your conversion fires on success, not on a click.
• One conversion per submission in Tag Assistant.
• Lead conversion actions are set to count One.
• Test submissions are deleted.

Still stuck? See My pixel or tag isn't firing.