diff --git a/app/sidekiq/evss/disability_compensation_form/submit_uploads.rb b/app/sidekiq/evss/disability_compensation_form/submit_uploads.rb
index b304d54670f..58a4bf6ecfe 100644
--- a/app/sidekiq/evss/disability_compensation_form/submit_uploads.rb
+++ b/app/sidekiq/evss/disability_compensation_form/submit_uploads.rb
@@ -107,7 +107,7 @@ def self.api_upload_provider(submission, document_type, supporting_evidence_atta
       # Recursively submits a file in a new instance of this job for each upload in the uploads list
       #
       # @param submission_id [Integer] The {Form526Submission} id
-      # @param upload_data [String] upload GUID in AWS S3
+      # @param upload_data [String] Form metadata for attachment, including upload GUID in AWS S3
       #
       def perform(submission_id, upload_data)
         Sentry.set_tags(source: '526EZ-all-claims')
@@ -124,7 +124,7 @@ def perform(submission_id, upload_data)
           raise Common::Exceptions::ValidationErrors, document_data unless document_data.valid?
 
           if Flipper.enabled?(:disability_compensation_use_api_provider_for_submit_veteran_upload)
-            upload_via_api_provider(submission, upload_data['attachmentId'], file_body, sea)
+            upload_via_api_provider(submission, upload_data, file_body, sea)
           else
             EVSS::DocumentsService.new(submission.auth_headers).upload(file_body, document_data)
           end
@@ -141,13 +141,17 @@ def perform(submission_id, upload_data)
       # We use these providers to iteratively migrate uploads to Lighthouse
       #
       # @param submission [Form526Submission]
-      # @document_type [string] VA internal document code for attachment type (e.g. L451)
-      # @file_body [string] Attachment file contents
-      # @attachment [SupportingEvidenceAttachment] Upload attachment record
-      def upload_via_api_provider(submission, document_type, file_body, attachment)
+      # @param upload_data [Hash] the form metadata for the attachment
+      # @param file_body [string] Attachment file contents
+      # @param attachment [SupportingEvidenceAttachment] Upload attachment record
+      def upload_via_api_provider(submission, upload_data, file_body, attachment)
+        document_type = upload_data['attachmentId']
         provider = self.class.api_upload_provider(submission, document_type, attachment)
 
-        upload_document = provider.generate_upload_document(attachment.converted_filename)
+        # Fall back to name in metadata if converted_filename returns nil; matches existing behavior
+        filename = attachment.converted_filename || upload_data['name']
+
+        upload_document = provider.generate_upload_document(filename)
         provider.submit_upload_document(upload_document, file_body)
       end
 
diff --git a/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb b/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb
index 95108d52873..8434fd2acf9 100644
--- a/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb
+++ b/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb
@@ -174,7 +174,7 @@
             claim_id: submission.submitted_claim_id,
             participant_id: user.participant_id,
             document_type: upload_data.first['attachmentId'],
-            file_name: attachment.converted_filename,
+            file_name: upload_data.first['name'],
             supporting_evidence_attachment: attachment
           )
         end
@@ -231,6 +231,32 @@
           expect(Lighthouse526DocumentUpload.where(**upload_attributes).count).to eq(1)
         end
 
+        # This is a possibility accounted for in the existing EVSS submission code.
+        # The original attachment object does not have a converted_filename.
+        context 'when the SupportingEvidenceAttachment returns a converted_filename' do
+          before do
+            attachment.update!(file_data: JSON.parse(attachment.file_data)
+                      .merge('converted_filename' => 'converted_filename.pdf').to_json)
+          end
+
+          let(:expected_lighthouse_document_with_converted_file_name) do
+            LighthouseDocument.new(
+              claim_id: submission.submitted_claim_id,
+              participant_id: user.participant_id,
+              document_type: upload_data.first['attachmentId'],
+              file_name: 'converted_filename.pdf',
+              supporting_evidence_attachment: attachment
+            )
+          end
+
+          it 'uses the converted_filename instead of the metadata in upload_data["name"]' do
+            expect(BenefitsDocuments::Form526::UploadSupplementalDocumentService).to receive(:call)
+              .with(file.read, expected_lighthouse_document_with_converted_file_name)
+
+            perform_upload
+          end
+        end
+
         context 'when Lighthouse returns an error response' do
           let(:error_response_body) do
             # From vcr_cassettes/lighthouse/benefits_claims/documents/lighthouse_form_526_document_upload_400.yml
@@ -292,7 +318,7 @@
           EVSSClaimDocument.new(
             evss_claim_id: submission.submitted_claim_id,
             document_type: upload_data.first['attachmentId'],
-            file_name: attachment.converted_filename
+            file_name: upload_data.first['name']
           )
         end