Set up SourceTag with Tally

Tally has a straightforward hidden fields feature. You define them in the form settings and SourceTag populates them when the form is embedded on your site.

What you need

• SourceTag installed on your website
• A Tally form embedded on your site

Step 1: Open your form in the Tally editor

Open your form in the Tally editor. You will add hidden fields directly in the form editor, not in the settings.

Step 2: Add hidden fields

1. In the Tally form editor, type /hidden to insert a Hidden field block
2. Set the field name to match the SourceTag field name exactly
3. Repeat for each field - type /hidden again each time

The field names must match exactly, including case and underscores.

Core fields (add these)

• st_fc_channel
• st_fc_detail_1
• st_fc_detail_2
• st_fc_detail_3
• st_fc_detail_4
• st_lc_channel
• st_lc_detail_1
• st_lc_detail_2
• st_lc_detail_3
• st_lc_detail_4
• st_fc_landing_page
• st_lc_landing_page

Optional extended fields

If you have enabled extended field groups in your SourceTag dashboard, also add:

• st_fc_click_id and st_lc_click_id (click IDs)
• st_visits (visit count)
• st_days_to_convert (days since first visit)
• st_device (device type)

See Captured Fields for the full list of available fields.

Step 3: Embed the form on your site

Use Tally’s embed code to place the form on your page. The page must also have the SourceTag script installed.

Tally embeds use cross-origin iframes, so SourceTag cannot populate the hidden fields by accessing the DOM directly. Instead, use the URL parameter approach: append the SourceTag field values as query parameters to the Tally embed URL. SourceTag will automatically append attribution data to the data-tally-src URL when it detects a Tally embed on the page.

<!-- Tally embed example -->
<iframe data-tally-src="https://tally.so/embed/YOUR_FORM_ID?alignLeft=1&hideTitle=1&transparentBackground=1" ...></iframe>
<script src="https://tally.so/widgets/embed.js"></script>

Tally maps URL parameters to hidden fields with matching names, so the data flows through automatically.

Step 4: Test

Visit the page with UTM parameters:

?utm_source=test&utm_medium=cpc&utm_campaign=tally-test

Submit the form. In Tally, go to your form’s Submissions tab and check the test entry. The hidden fields should contain your attribution data.

Tips

• Field names are case-sensitive. Copy them from the Fields page in your SourceTag dashboard to avoid typos.
• Tally hidden fields will appear in your submission data, integrations (Zapier, webhooks, etc.) and notification emails.
• If hidden fields are showing as empty, check that SourceTag is loading on the same page as the embedded form.
• Tally’s free plan supports hidden fields.