How to create and implement templates that allow for information to be automatically filled in on envelope creation using Docusign API

Problem

I’m using the DocuSign eSignature API with composite templates and can’t get prefill (sender-filled) text tabs to populate when creating an envelope.

What I’m Doing

• I built a template builder that places PDF annotations (via Nutrient)

• These are converted into anchor-based Text tabs in a DocuSign template

• Prefill fields are created like:

  • Anchor: PreFillLegalCompanyName_GUID

  • TabLabel: LegalCompanyName

At send time:

• I retrieve the tabs

• Map TabLabel → value (e.g. "LegalCompanyName" → "Test Customer LLC")

• Send values using an inline template

Example:

signer.Tabs = new Tabs
{
    TextTabs = new List<Text>
    {
        new Text
        {
            TabLabel = "LegalCompanyName",
            Value = "Test Customer LLC"
        }
    }
};

Issue

The tab exists in the document, but the value is not populated when the envelope is created.

What I’ve Tried

• Matching TabLabel exactly (verified from template)

• Applying tabs on the same recipient as the server template

• Using a separate inline template for prefills

• Verifying anchor strings and tab metadata

None of these resulted in the value being applied.

Question

What is the correct way to populate prefill text tabs when using composite templates?

• Do prefill tabs need to be assigned differently in the template?

• Should values be applied in a specific inline template or recipient context?

• Do anchor-based tabs behave differently when setting values via TabLabel?

Expected Result

The document should be pre-filled (e.g. LegalCompanyName = "Test Customer LLC") before the recipient views it.

Any guidance would be appreciated.