diff --git a/app/controllers/idv/in_person/ssn_controller.rb b/app/controllers/idv/in_person/ssn_controller.rb
index c78c53a4de5..f57078a8ea8 100644
--- a/app/controllers/idv/in_person/ssn_controller.rb
+++ b/app/controllers/idv/in_person/ssn_controller.rb
@@ -64,10 +64,7 @@ def self.step_info
           controller: self,
           next_steps: [:ipp_verify_info],
           preconditions: ->(idv_session:, user:) { idv_session.ipp_document_capture_complete? },
-          undo_step: ->(idv_session:, user:) do
-            idv_session.ssn = nil
-            idv_session.threatmetrix_session_id = nil
-          end,
+          undo_step: ->(idv_session:, user:) { idv_session.ssn = nil },
         )
       end
 
diff --git a/app/controllers/idv/ssn_controller.rb b/app/controllers/idv/ssn_controller.rb
index 4c7934c54d7..1c99d712df4 100644
--- a/app/controllers/idv/ssn_controller.rb
+++ b/app/controllers/idv/ssn_controller.rb
@@ -62,10 +62,7 @@ def self.step_info
         controller: self,
         next_steps: [:verify_info],
         preconditions: ->(idv_session:, user:) { idv_session.remote_document_capture_complete? },
-        undo_step: ->(idv_session:, user:) do
-          idv_session.ssn = nil
-          idv_session.threatmetrix_session_id = nil
-        end,
+        undo_step: ->(idv_session:, user:) { idv_session.ssn = nil },
       )
     end
 
diff --git a/spec/controllers/idv/link_sent_controller_spec.rb b/spec/controllers/idv/link_sent_controller_spec.rb
index 8b1747897b4..a82da6328f6 100644
--- a/spec/controllers/idv/link_sent_controller_spec.rb
+++ b/spec/controllers/idv/link_sent_controller_spec.rb
@@ -125,6 +125,22 @@
       expect(subject.idv_session.applicant).to be_nil
     end
 
+    # This is a regression spec that was introduced for a bug that occured
+    # when calling `undo_step` on the SSN controller step info caused the
+    # TMx session ID to be deleted when this step was resubmitted
+    #
+    # See https://cm-jira.usa.gov/browse/LG-14127
+    # See https://github.com/18F/identity-idp/pull/11091#discussion_r1718831233
+    it 'does not delete the TMx session ID' do
+      subject.idv_session.ssn = '900-12-1234'
+      subject.idv_session.threatmetrix_session_id = 'super-cool-test-value'
+
+      put :update
+
+      expect(subject.idv_session.ssn).to be_nil
+      expect(subject.idv_session.threatmetrix_session_id).to_not be_nil
+    end
+
     it 'sends analytics_submitted event' do
       put :update
 
diff --git a/spec/policies/idv/flow_policy_spec.rb b/spec/policies/idv/flow_policy_spec.rb
index 885649250d4..0e5c3e5fb60 100644
--- a/spec/policies/idv/flow_policy_spec.rb
+++ b/spec/policies/idv/flow_policy_spec.rb
@@ -46,7 +46,6 @@
         idv_session.had_barcode_attention_error = true
 
         idv_session.ssn = Idp::Constants::MOCK_IDV_APPLICANT_WITH_SSN[:ssn]
-        idv_session.threatmetrix_session_id = SecureRandom.uuid
 
         idv_session.address_edited = true
       end
@@ -68,7 +67,6 @@
         expect(idv_session.had_barcode_attention_error).to be_nil
 
         expect(idv_session.ssn).to be_nil
-        expect(idv_session.threatmetrix_session_id).to be_nil
 
         expect(idv_session.address_edited).to be_nil
       end
@@ -90,7 +88,6 @@
         idv_session.had_barcode_attention_error = true
 
         idv_session.ssn = nil
-        idv_session.threatmetrix_session_id = SecureRandom.uuid
 
         idv_session.address_edited = true
 
@@ -141,8 +138,6 @@
 
           idv_session.had_barcode_read_failure
           idv_session.had_barcode_attention_error
-
-          idv_session.threatmetrix_session_id
         }
       end
     end