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How to capture GCLID and UTMs in hidden form fields

Live guide · Checked 28 October 2026 · Updated 28 October 2026 · Checked every week against Forms's own help pages

Save the Google click ID and campaign tags when someone lands, and send them with the form, so your CRM knows which ad every lead came from.

Time

25 minutes

You will need

• Edit access to your forms (to add hidden fields)
• Google Tag Manager on your site
• Auto-tagging on in Google Ads (Admin > Account settings)

Stuck?

Troubleshooting or ask us a question

Step by step

1. Add hidden fields to your forms

   In your form builder add hidden fields with these exact names. Most builders call them Hidden fields:

   TextCopy

   gclid
   utm_source
   utm_medium
   utm_campaign
   utm_term
   utm_content

2. Save the values when people land

   Add this as a Tag Manager Custom HTML tag on All Pages. It keeps the click ID and campaign tags for 90 days (Google accepts offline conversions up to 90 days after a click):

   HTMLCopy

   <script>
   (function () {
     var KEYS = ['gclid', 'gbraid', 'wbraid', 'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content'];
     var q = new URLSearchParams(location.search), saved = {};
     try { saved = JSON.parse(localStorage.getItem('lead_src') || '{}'); } catch (e) {}
     var fresh = KEYS.some(function (k) { return q.get(k); });
     if (fresh) {
       saved = { at: Date.now() };
       KEYS.forEach(function (k) { if (q.get(k)) saved[k] = q.get(k); });
       try { localStorage.setItem('lead_src', JSON.stringify(saved)); } catch (e) {}
     }
     if (saved.at && Date.now() - saved.at > 90 * 864e5) saved = {};
     function fill() {
       KEYS.forEach(function (k) {
         document.querySelectorAll('input[name="' + k + '"]').forEach(function (el) { if (saved[k] && !el.value) el.value = saved[k]; });
       });
     }
     fill();
     new MutationObserver(fill).observe(document.body, { childList: true, subtree: true });
   })();
   </script>

3. Map the fields in your CRM

   Make matching fields in your CRM (for example GCLIDCopy and UTM CampaignCopy) and map the form's hidden fields to them, so every new lead keeps them.

4. Test with a fake click ID

   Open your site with a test address, then send the form:

   TextCopy

   https://www.example.com/?gclid=TEST123&utm_source=google&utm_campaign=test

   Check the new lead in your CRM shows TEST123Copy and testCopy.

5. Check the value survives a few pages

   Land on the test address, click to two other pages, then send the form. The click ID should still be there: that's what the 90-day saving is for.

6. Publish

   Submit and Publish in Tag Manager. You're ready for the offline conversions Secret Setup.