Tracking Form Submissions with GTM


In Google Tag Manager, our conversion tags are triggered by a visit to the form confirmation page.

Unfortunately, we are having a problem with display advertising fraud. I suspect bot networks are simply launching our thank-you page – without filling out the form – and triggering our conversion tags.

How can I create a trigger that only fires the form is successfully submitted using Google Tag Manager?

The native GTM integration appears to fire this kind of event:

The native integration via Script Manager will automatically place the GTM code on your pages. This will not automatically send the form submission event to GTM, but will allow you to set up a listener within GTM to capture the form submit data layer.


Hi Phillip,
If you added GTM though the domain scripts in Unbounce there should be an event that’s fired upon a successful form submission labeled as “gtm.formSubmit”. With this event you can trigger any conversions (instead of using a url based conversion).

In GTM you’ll want to:

  1. Create a new trigger
  2. Set this trigger as a custom event
  3. Event name is “gtm.formSubmit”
  4. You can leave “This trigger fires on… All Custom Events” (unless you want to add conditions)
  5. For your conversion tags in GTM, set the trigger you just made

And remember, you can use the GTM Preview button to have a debug window to test and see what tags and triggers are firing. Any changes you make in GTM while in preview mode need to be saved to update. Just click the “Refresh” button in GTM when preview mode is enabled.

If you have any questions, let me know!
Marc at ParaCore


Thanks Marc!

I do have GTM added through Unbounce’s domain scripts integration.

gtm.formSubmit does not fire when I submit the form.

When I add the “Form Submission” trigger, gtm.formSubmit fires on page load, NOT when the form is submitted.



Okay, taking a look now. A couple questions for you:

  1. Are you testing a successful form submission?
  2. Are you checking the debug window before the redirect to the thank-you page happens? It will only show on the landing page, but will go away when it redirects you to the thank-you page.
  3. I may have not been clear! Do not use the built in “Form Submission” trigger in GTM. This is a general form listener. You will want to create a trigger using “Custom Event”.
  4. Are you using the native form functionality of unbounce? (Or is it a hubspot form, marketo, or some other service?)

I did a test with our unbounce account to make sure the gtm.formSubmit still fires when using a redirect and it shows up for me! The screenshot below is a dummy page I made to test:

Edit: Maybe looking at our example might help you. Here’s the landing page link, alongside the GTM preview link. I recommend using incognito to prevent cookies from conflicting from your current testing.

You should be able to see after the form submission that the gtm.formSubmit event fires, and that the “Unbounce Form Submission” trigger is fired.


Awesome! Thanks so much Marc. I think I got it!


Great Phillip! Glad to hear :smile:


I just found out my problem as to why this solution wasn’t working for me, the problem: I had manually installed GTM, not used the integration from Unbounce. Once I did that, voila!