diff --git a/app/models/form526_submission.rb b/app/models/form526_submission.rb
index bc4975d2d8e..e08e952c3e8 100644
--- a/app/models/form526_submission.rb
+++ b/app/models/form526_submission.rb
@@ -23,9 +23,7 @@ class Form526Submission < ApplicationRecord
                     :submit_flashes,
                     :poll_form526_pdf,
                     :cleanup,
-                    additional_class_logs: {
-                      action: 'Begin as anciliary 526 submission'
-                    },
+                    additional_class_logs: { action: 'Begin as anciliary 526 submission' },
                     additional_instance_logs: {
                       saved_claim_id: %i[saved_claim id],
                       user_uuid: %i[user_uuid]
@@ -54,13 +52,11 @@ class Form526Submission < ApplicationRecord
   has_kms_key
   has_encrypted :auth_headers_json, :birls_ids_tried, :form_json, key: :kms_key, **lockbox_options
 
-  belongs_to :saved_claim,
-             class_name: 'SavedClaim::DisabilityCompensation',
-             inverse_of: false
+  belongs_to :saved_claim, class_name: 'SavedClaim::DisabilityCompensation', inverse_of: false
 
   has_many :form526_job_statuses, dependent: :destroy
   has_many :form526_submission_remediations, dependent: :destroy
-  belongs_to :user_account, dependent: nil, optional: true
+  belongs_to :user_account, dependent: nil
 
   validates(:auth_headers_json, presence: true)
   enum :backup_submitted_claim_status, { accepted: 0, rejected: 1, paranoid_success: 2 }
@@ -163,9 +159,7 @@ def submit_with_birls_id_that_hasnt_been_tried_yet!(
 
   # Note that the User record is cached in Redis -- `User.redis_namespace_ttl`
   def get_first_name
-    user = User.find(user_uuid)
-    user&.first_name&.upcase.presence ||
-      auth_headers&.dig('va_eauth_firstName')&.upcase
+    user&.first_name&.upcase.presence || auth_headers&.dig('va_eauth_firstName')&.upcase
   end
 
   # Checks against the User record first, and then resorts to checking the auth_headers
@@ -174,15 +168,13 @@ def get_first_name
   # @return [Hash] of the user's full name (first, middle, last, suffix)
   #
   def full_name
-    name_hash = User.find(user_uuid)&.full_name_normalized
+    name_hash = user&.full_name_normalized
     return name_hash if name_hash&.[](:first).present?
 
-    {
-      first: auth_headers&.dig('va_eauth_firstName')&.capitalize,
+    { first: auth_headers&.dig('va_eauth_firstName')&.capitalize,
       middle: nil,
       last: auth_headers&.dig('va_eauth_lastName')&.capitalize,
-      suffix: nil
-    }
+      suffix: nil }
   end
 
   # form_json is memoized here so call invalidate_form_hash after updating form_json
@@ -468,22 +460,11 @@ def last_remediation
   end
 
   def account
-    # first, check for an ICN on the UserAccount associated to the submission, return it if found
-    account = user_account
-    return account if account&.icn.present?
-
-    # next, check past submissions for different UserAccounts that might have ICNs
-    past_submissions = get_past_submissions
-    account = find_user_account_with_icn(past_submissions, 'past submissions')
-    return account if account.present? && account.icn.present?
-
-    # next, check for any historical UserAccounts for that user which might have an ICN
-    user_verifications = get_user_verifications
-    account = find_user_account_with_icn(user_verifications, 'user verifications')
-    return account if account.present? && account.icn.present?
+    return user_account if user_account&.icn.present?
 
-    # failing all the above, default to an Account lookup
-    Account.lookup_by_user_uuid(user_uuid)
+    Rails.logger.info('Form526Submission::account - no UserAccount ICN found', log_payload)
+    # query MPI by EDIPI first & attributes second for user ICN, return in OpenStruct
+    get_icn_from_mpi
   end
 
   # Send the Submitted Email - when the Veteran has clicked the "submit" button in va.gov
@@ -493,8 +474,7 @@ def account
   # @param invoker: string where the Received Email trigger is being called from
   def send_submitted_email(invoker)
     if Flipper.enabled?(:disability_526_send_form526_submitted_email)
-      Rails.logger.info("Form526SubmittedEmailJob called for user #{user_uuid},
-                                                          submission: #{id} from #{invoker}")
+      Rails.logger.info("Form526SubmittedEmailJob called for user #{user_uuid}, submission: #{id} from #{invoker}")
       first_name = get_first_name
       params = personalization_parameters(first_name)
       Form526SubmittedEmailJob.perform_async(params)
@@ -506,8 +486,7 @@ def send_submitted_email(invoker)
   # Backup Path: when Form526StatusPollingJob reaches "paranoid_success" status
   # @param invoker: string where the Received Email trigger is being called from
   def send_received_email(invoker)
-    Rails.logger.info("Form526ConfirmationEmailJob called for user #{user_uuid},
-                                                          submission: #{id} from #{invoker}")
+    Rails.logger.info("Form526ConfirmationEmailJob called for user #{user_uuid}, submission: #{id} from #{invoker}")
     first_name = get_first_name
     params = personalization_parameters(first_name)
     Form526ConfirmationEmailJob.perform_async(params)
@@ -612,7 +591,6 @@ def submit_form_8940
   end
 
   def submit_flashes
-    user = User.find(user_uuid)
     # Note that the User record is cached in Redis -- `User.redis_namespace_ttl`
     # If this method runs after the TTL, then the flashes will not be applied -- a possible bug.
     BGS::FlashUpdater.perform_async(id) if user && Flipper.enabled?(:disability_compensation_flashes, user)
@@ -630,27 +608,51 @@ def cleanup
     EVSS::DisabilityCompensationForm::SubmitForm526Cleanup.perform_async(id)
   end
 
-  def find_user_account_with_icn(records, record_type)
-    records.pluck(:user_account_id).uniq.each do |user_account_id|
-      user_account = UserAccount.find(user_account_id)
-      next if user_account&.icn.blank?
-
-      Rails.logger.info("ICN not found on submission #{id}, " \
-                        "using ICN for user account #{user_account_id} instead (based on #{record_type})")
-      return user_account
+  def get_icn_from_mpi
+    edipi_response_profile = edipi_mpi_profile_query(auth_headers['va_eauth_dodedipnid'])
+    if edipi_response_profile&.icn.present?
+      OpenStruct.new(icn: edipi_response_profile.icn)
+    else
+      Rails.logger.info('Form526Submission::account - unable to look up MPI profile with EDIPI', log_payload)
+      attributes_response_profile = attributes_mpi_profile_query(auth_headers)
+      if attributes_response_profile&.icn.present?
+        OpenStruct.new(icn: attributes_response_profile.icn)
+      else
+        Rails.logger.info('Form526Submission::account - no ICN present', log_payload)
+        OpenStruct.new(icn: nil)
+      end
     end
   end
 
-  def get_past_submissions
-    Form526Submission.where(user_uuid:).where.not(user_account_id:)
+  def edipi_mpi_profile_query(edipi)
+    return unless edipi
+
+    edipi_response = mpi_service.find_profile_by_edipi(edipi:)
+    edipi_response.profile if edipi_response.ok? && edipi_response.profile.icn.present?
+  end
+
+  def attributes_mpi_profile_query(auth_headers)
+    required_attributes = %w[va_eauth_firstName va_eauth_lastName va_eauth_birthdate va_eauth_pnid]
+    return unless required_attributes.all? { |attr| auth_headers[attr].present? }
+
+    attributes_response = mpi_service.find_profile_by_attributes(
+      first_name: auth_headers['va_eauth_firstName'],
+      last_name: auth_headers['va_eauth_lastName'],
+      birth_date: auth_headers['va_eauth_birthdate']&.to_date.to_s,
+      ssn: auth_headers['va_eauth_pnid']
+    )
+    attributes_response.profile if attributes_response.ok? && attributes_response.profile.icn.present?
+  end
+
+  def log_payload
+    @log_payload ||= { user_uuid:, submission_id: id }
+  end
+
+  def mpi_service
+    @mpi_service ||= MPI::Service.new
   end
 
-  def get_user_verifications
-    UserVerification.where(idme_uuid: user_uuid)
-                    .or(UserVerification.where(backing_idme_uuid: user_uuid))
-                    .or(UserVerification.where(logingov_uuid: user_uuid))
-                    .or(UserVerification.where(mhv_uuid: user_uuid))
-                    .or(UserVerification.where(dslogon_uuid: user_uuid))
-                    .where.not(user_account_id:)
+  def user
+    @user ||= User.find(user_uuid)
   end
 end
diff --git a/rakelib/form526.rake b/rakelib/form526.rake
index 1ee1b31f370..1722180f4c7 100644
--- a/rakelib/form526.rake
+++ b/rakelib/form526.rake
@@ -518,11 +518,15 @@ namespace :form526 do
         end
 
         vname = "#{fs.auth_headers['va_eauth_firstName']} #{fs.auth_headers['va_eauth_lastName']}"
-        icn = Account.lookup_by_user_uuid(fs.user_uuid).first&.icn
+        icn = fs.user_account&.icn
         if icn.blank?
-          # TODO: make this work for blank icn's
-          puts "icn blank #{fs.id}"
-          next
+          mpi_response = MPI::Service.new.find_profile_by_edipi(edipi: fs['va_eauth_dodedipnid'])
+          if mpi_response.ok? && mpi_response.profile.icn.present?
+            icn = mpi_response.profile.icn
+          else
+            puts "icn blank #{fs.id}"
+            next
+          end
         end
         user = OpenStruct.new(participant_id: fs.auth_headers['va_eauth_pid'], icn:, common_name: vname,
                               ssn:)
@@ -684,42 +688,26 @@ namespace :form526 do
   desc 'pretty print MPI profile for submission'
   task mpi: :environment do |_, args|
     def puts_mpi_profile(submission)
-      ids = {}
-      ids[:edipi] = edipi submission.auth_headers
-      ids[:icn] = icn ids[:edipi]
+      edipi = submission.auth_headers['va_eauth_dodedipnid']
+      raise Error, 'no edipi' unless edipi
 
-      pp mpi_profile(user_identity(**ids)).as_json
+      ids = { edipi:, icn: submission.user_account&.icn }
+
+      pp mpi_profile(ids).as_json
     end
 
-    def mpi_profile(user_identity)
-      if user_identity.mhv_icn
-        find_profile_response = MPI::Service.new.find_profile_by_identifier(identifier: user_identity.mhv_icn,
+    def mpi_profile(ids)
+      if ids[:icn]
+        find_profile_response = MPI::Service.new.find_profile_by_identifier(identifier: ids[:icn],
                                                                             identifier_type: MPI::Constants::ICN)
       else
-        find_profile_response = MPI::Service.new.find_profile_by_edipi(edipi: user_identity.edipi)
+        find_profile_response = MPI::Service.new.find_profile_by_edipi(edipi: ids[:edipi])
       end
       raise find_profile_response.error if find_profile_response.error
 
       find_profile_response.profile
     end
 
-    def user_identity(icn:, edipi:)
-      OpenStruct.new mhv_icn: icn, edipi:
-    end
-
-    def edipi(auth_headers)
-      auth_headers['va_eauth_dodedipnid']
-    end
-
-    def icn(edipi)
-      raise Error, 'no edipi' unless edipi
-
-      icns = Account.where(edipi:).pluck :icn
-      raise Error, 'multiple icns' if icns.uniq.length > 1
-
-      icns.first
-    end
-
     Form526Submission.where(id: args.extras).find_each { |sub| puts_mpi_profile sub }
   end
 
diff --git a/spec/factories/form526_submissions.rb b/spec/factories/form526_submissions.rb
index 27ebdc9cbee..86f358d9716 100644
--- a/spec/factories/form526_submissions.rb
+++ b/spec/factories/form526_submissions.rb
@@ -3,9 +3,11 @@
 FactoryBot.define do
   factory :form526_submission do
     transient do
-      user { create(:disabilities_compensation_user) }
+      user_verification { create(:idme_user_verification) }
+      user { create(:disabilities_compensation_user, idme_uuid: user_verification.idme_uuid) }
       submissions_path { Rails.root.join(*'/spec/support/disability_compensation_form/submissions'.split('/')).to_s }
     end
+    user_account { user_verification.user_account }
     user_uuid { user.uuid }
     saved_claim { create(:va526ez) }
     submitted_claim_id { nil }
diff --git a/spec/lib/sidekiq/form526_backup_submission_process/processor_spec.rb b/spec/lib/sidekiq/form526_backup_submission_process/processor_spec.rb
index f0227305a01..7011b801ebd 100644
--- a/spec/lib/sidekiq/form526_backup_submission_process/processor_spec.rb
+++ b/spec/lib/sidekiq/form526_backup_submission_process/processor_spec.rb
@@ -28,8 +28,10 @@
   end
 
   describe '#choose_provider' do
-    let(:account) { create(:account) }
-    let(:submission) { create(:form526_submission, user_uuid: account.idme_uuid, submit_endpoint: 'claims_api') }
+    let(:user) { create(:user, :loa3, :with_terms_of_use_agreement) }
+    let(:user_account) { user.user_account }
+    let(:icn) { user_account.icn }
+    let(:submission) { create(:form526_submission, user_account:, submit_endpoint: 'claims_api') }
 
     it 'delegates to the ApiProviderFactory with the correct data' do
       auth_headers = {}
@@ -38,7 +40,7 @@
           type: ApiProviderFactory::FACTORIES[:generate_pdf],
           provider: ApiProviderFactory::API_PROVIDER[:lighthouse],
           options: { auth_headers:, breakered: true },
-          current_user: OpenStruct.new({ flipper_id: submission.user_uuid, icn: account.icn }),
+          current_user: OpenStruct.new({ flipper_id: submission.user_uuid, icn: }),
           feature_toggle: nil
         }
       )
@@ -59,7 +61,7 @@
           type: ApiProviderFactory::FACTORIES[:generate_pdf],
           provider: ApiProviderFactory::API_PROVIDER[:lighthouse],
           options: { auth_headers: submission.auth_headers, breakered: true },
-          current_user: OpenStruct.new({ flipper_id: submission.user_uuid, icn: account.icn }),
+          current_user: OpenStruct.new({ flipper_id: submission.user_uuid, icn: }),
           feature_toggle: nil
         }
       ).and_call_original
diff --git a/spec/lib/sidekiq/form526_backup_submission_process/submit_spec.rb b/spec/lib/sidekiq/form526_backup_submission_process/submit_spec.rb
index 18627e39afd..b3336161bfe 100644
--- a/spec/lib/sidekiq/form526_backup_submission_process/submit_spec.rb
+++ b/spec/lib/sidekiq/form526_backup_submission_process/submit_spec.rb
@@ -16,7 +16,8 @@
       .and_return('access_token')
   end
 
-  let(:user) { create(:user, :loa3) }
+  let(:user_account) { create(:user_account, icn: '123498767V234859') }
+  let(:user) { create(:user, :loa3, icn: user_account.icn) }
   let(:auth_headers) do
     EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
   end
@@ -27,7 +28,7 @@
       allow(Settings.form526_backup).to receive(:enabled).and_return(false)
     end
 
-    let!(:submission) { create(:form526_submission, :with_everything) }
+    let!(:submission) { create(:form526_submission, :with_everything, user_account:) }
 
     it 'creates a submission job' do
       expect { subject.perform_async(submission.id) }.to change(subject.jobs, :size).by(1)
@@ -42,7 +43,7 @@
     let(:timestamp) { Time.now.utc }
 
     context 'when all retries are exhausted' do
-      let!(:form526_submission) { create(:form526_submission) }
+      let!(:form526_submission) { create(:form526_submission, user_account:) }
       let!(:form526_job_status) { create(:form526_job_status, :retryable_error, form526_submission:, job_id: 1) }
 
       it 'updates a StatsD counter and updates the status on an exhaustion event' do
@@ -111,7 +112,7 @@
         allow(Settings.form526_backup).to receive_messages(submission_method: payload_method, enabled: true)
       end
 
-      let!(:submission) { create(:form526_submission, :with_everything) }
+      let!(:submission) { create(:form526_submission, :with_everything, user_account:) }
       let!(:upload_data) { submission.form[Form526Submission::FORM_526_UPLOADS] }
 
       context 'successfully' do
@@ -222,7 +223,7 @@
       allow(Settings.form526_backup).to receive_messages(submission_method: 'single', enabled: true)
     end
 
-    let!(:submission) { create(:form526_submission, :with_non_pdf_uploads) }
+    let!(:submission) { create(:form526_submission, :with_non_pdf_uploads, user_account:) }
     let!(:upload_data) { submission.form[Form526Submission::FORM_526_UPLOADS] }
 
     context 'converts non-pdf files to pdf' do
diff --git a/spec/lib/sidekiq/form526_job_status_tracker/job_tracker_spec.rb b/spec/lib/sidekiq/form526_job_status_tracker/job_tracker_spec.rb
index 389ebe1b8c4..6a6e2c86b05 100644
--- a/spec/lib/sidekiq/form526_job_status_tracker/job_tracker_spec.rb
+++ b/spec/lib/sidekiq/form526_job_status_tracker/job_tracker_spec.rb
@@ -18,7 +18,8 @@
   end
 
   context 'with an exhausted callback message' do
-    let!(:form526_submission) { create(:form526_submission) }
+    let(:user_account) { create(:user_account, icn: '123498767V234859') }
+    let!(:form526_submission) { create(:form526_submission, user_account:) }
     let!(:form526_job_status) do
       create(:form526_job_status, job_id: msg['jid'], form526_submission:)
     end
diff --git a/spec/models/form526_submission_spec.rb b/spec/models/form526_submission_spec.rb
index b3138b52c94..dbee68fda65 100644
--- a/spec/models/form526_submission_spec.rb
+++ b/spec/models/form526_submission_spec.rb
@@ -7,6 +7,7 @@
   subject do
     Form526Submission.create(
       user_uuid: user.uuid,
+      user_account:,
       saved_claim_id: saved_claim.id,
       auth_headers_json: auth_headers.to_json,
       form_json:,
@@ -15,8 +16,13 @@
     )
   end
 
-  let(:user) { create(:user, :loa3, first_name: 'Beyonce', last_name: 'Knowles') }
-  let(:user_account) { create(:user_account, icn: user.icn, id: user.user_account_uuid) }
+  let(:user_account) { create(:user_account) }
+  let(:user) do
+    create(:user, :loa3, first_name: 'Beyonce',
+                         last_name: 'Knowles',
+                         icn: user_account.icn,
+                         idme_uuid: SecureRandom.uuid)
+  end
   let(:auth_headers) do
     EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
   end
@@ -657,6 +663,7 @@ def expect_no_max_cfi_logged(diagnostic_code)
       headers = JSON.parse auth_headers.to_json
       Form526Submission.new(
         user_uuid: user.uuid,
+        user_account:,
         saved_claim_id: saved_claim.id,
         auth_headers_json: headers.to_json,
         form_json:,
@@ -741,6 +748,7 @@ def expect_no_max_cfi_logged(diagnostic_code)
       headers['va_eauth_birlsfilenumber'] = birls_id
       Form526Submission.new(
         user_uuid: user.uuid,
+        user_account:,
         saved_claim_id: saved_claim.id,
         auth_headers_json: headers.to_json,
         form_json:,
@@ -767,6 +775,7 @@ def expect_no_max_cfi_logged(diagnostic_code)
       subject do
         Form526Submission.new(
           user_uuid: user.uuid,
+          user_account:,
           saved_claim_id: saved_claim.id,
           form_json:,
           birls_ids_tried: birls_ids_tried.to_json
@@ -793,6 +802,7 @@ def expect_no_max_cfi_logged(diagnostic_code)
       headers['va_eauth_birlsfilenumber'] = birls_id
       Form526Submission.new(
         user_uuid: user.uuid,
+        user_account:,
         saved_claim_id: saved_claim.id,
         auth_headers_json: headers.to_json,
         form_json:,
@@ -835,6 +845,7 @@ def expect_no_max_cfi_logged(diagnostic_code)
       headers['va_eauth_birlsfilenumber'] = birls_id
       Form526Submission.new(
         user_uuid: user.uuid,
+        user_account:,
         saved_claim_id: saved_claim.id,
         auth_headers_json: headers.to_json,
         form_json:,
@@ -1341,10 +1352,11 @@ def expect_no_max_cfi_logged(diagnostic_code)
 
     before { create(:idme_user_verification, idme_uuid: user.idme_uuid, user_account:) }
 
+    let(:user_account) { create(:user_account, icn: '123498767V234859') }
     let(:form_526_submission) do
       Form526Submission.create(
         user_uuid: user.uuid,
-        user_account: user.user_account,
+        user_account:,
         saved_claim_id: saved_claim.id,
         auth_headers_json: auth_headers.to_json,
         form_json: File.read("spec/support/disability_compensation_form/submissions/#{form_json_filename}")
@@ -1563,72 +1575,97 @@ def expect_no_max_cfi_logged(diagnostic_code)
   end
 
   describe 'ICN retrieval' do
-    context 'various ICN retrieval scenarios' do
-      let(:user) { create(:user, :loa3) }
-      let(:auth_headers) do
-        EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
-      end
-      let(:submission) do
-        create(:form526_submission,
-               user_uuid: user.uuid,
-               auth_headers_json: auth_headers.to_json,
-               saved_claim_id: saved_claim.id)
-      end
-      let!(:form526_submission) { create(:form526_submission) }
+    let(:user) { create(:user, :loa3) }
+    let(:auth_headers) do
+      EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
+    end
+    let(:submission) do
+      create(:form526_submission,
+             user_uuid: user.uuid,
+             auth_headers_json: auth_headers.to_json,
+             saved_claim_id: saved_claim.id)
+    end
+    let!(:form526_submission) { create(:form526_submission) }
+    let(:expected_log_payload) { { user_uuid: user.uuid, submission_id: submission.id } }
 
-      it 'submissions user account has an ICN, as expected' do
+    context 'when the submission includes a UserAccount with an ICN, as expected' do
+      it 'uses the submission\'s user account ICN' do
         submission.user_account = UserAccount.new(icn: '123498767V222222')
         account = submission.account
         expect(account.icn).to eq('123498767V222222')
       end
+    end
 
-      it 'submissions user account has no ICN, default to Account lookup' do
-        submission.user_account = UserAccount.new(icn: nil)
-        account = submission.account
-        expect(account.icn).to eq('123498767V234859')
-      end
+    context 'when the submission does not have a UserAccount with an ICN' do
+      let(:mpi_profile) { build(:mpi_profile) }
+      let(:mpi_profile_response) { create(:find_profile_response, profile: mpi_profile) }
+      let(:edipi_profile_response) { mpi_profile_response }
+      let(:no_user_account_icn_message) { 'Form526Submission::account - no UserAccount ICN found' }
 
-      it 'submission has NO user account, default to Account lookup' do
-        account = submission.account
-        expect(account.icn).to eq('123498767V234859')
+      before do
+        allow_any_instance_of(MPI::Service).to receive(:find_profile_by_edipi).and_return(edipi_profile_response)
       end
 
-      it 'submissions user account has no ICN, lookup from past submissions' do
-        user_account_with_icn = UserAccount.create!(icn: '123498767V111111')
-        create(:form526_submission, user_uuid: submission.user_uuid, user_account: user_account_with_icn)
+      it 'uses the auth_headers EDIPI to look up account information from MPI' do
         submission.user_account = UserAccount.create!(icn: nil)
         submission.save!
+        expect(Rails.logger).to receive(:info).with(no_user_account_icn_message, expected_log_payload)
+        expect_any_instance_of(MPI::Service).to receive(:find_profile_by_edipi).with(edipi: user.edipi)
         account = submission.account
-        expect(account.icn).to eq('123498767V111111')
+        expect(account.icn).to eq(mpi_profile.icn)
       end
 
-      it 'lookup ICN from user verifications, idme_uuid defined' do
-        user_account_with_icn = UserAccount.create!(icn: '123498767V333333')
-        UserVerification.create!(idme_uuid: submission.user_uuid, user_account_id: user_account_with_icn.id)
-        submission.user_account = UserAccount.create!(icn: nil)
-        submission.save!
-        account = submission.account
-        expect(account.icn).to eq('123498767V333333')
-      end
+      context 'when the MPI lookup by EDIPI fails' do
+        let(:edipi_profile_response) { create(:find_profile_not_found_response) }
+        let(:attributes_profile_response) { mpi_profile_response }
+        let(:no_mpi_by_edipi_message) { 'Form526Submission::account - unable to look up MPI profile with EDIPI' }
 
-      it 'lookup ICN from user verifications, backing_idme_uuid defined' do
-        user_account_with_icn = UserAccount.create!(icn: '123498767V444444')
-        UserVerification.create!(dslogon_uuid: Faker::Internet.uuid, backing_idme_uuid: submission.user_uuid,
-                                 user_account_id: user_account_with_icn.id)
-        submission.user_account = UserAccount.create!(icn: nil)
-        submission.save!
-        account = submission.account
-        expect(account.icn).to eq('123498767V444444')
-      end
+        before do
+          allow(Rails.logger).to receive(:info).with(no_user_account_icn_message,
+                                                     expected_log_payload).and_call_original
+          allow_any_instance_of(MPI::Service).to receive(:find_profile_by_attributes)
+                                             .and_return(attributes_profile_response)
+        end
 
-      it 'lookup ICN from user verifications, alternate provider id defined' do
-        user_account_with_icn = UserAccount.create!(icn: '123498767V555555')
-        UserVerification.create!(dslogon_uuid: submission.user_uuid, backing_idme_uuid: Faker::Internet.uuid,
-                                 user_account_id: user_account_with_icn.id)
-        submission.user_account = UserAccount.create!(icn: nil)
-        submission.save!
-        account = submission.account
-        expect(account.icn).to eq('123498767V555555')
+        it 'uses the auth_headers user attributes to look up account information from MPI' do
+          submission.user_account = UserAccount.create!(icn: nil)
+          submission.save!
+          expect(Rails.logger).to receive(:info).with(no_mpi_by_edipi_message, expected_log_payload)
+          expect_any_instance_of(MPI::Service).to receive(:find_profile_by_attributes).with(
+            first_name: user.first_name,
+            last_name: user.last_name,
+            ssn: user.ssn,
+            birth_date: user.birth_date
+          )
+          account = submission.account
+          expect(account.icn).to eq(mpi_profile.icn)
+        end
+
+        context 'when the MPI lookup by attributes fails' do
+          let(:attributes_profile_response) { create(:find_profile_not_found_response) }
+          let(:no_icn_found_message) { 'Form526Submission::account - no ICN present' }
+
+          before do
+            allow(Rails.logger).to receive(:info).with(no_user_account_icn_message,
+                                                       expected_log_payload).and_call_original
+            allow(Rails.logger).to receive(:info).with(no_mpi_by_edipi_message, expected_log_payload).and_call_original
+          end
+
+          it 'does not return a UserAccount with an ICN' do
+            submission.user_account = UserAccount.create!(icn: nil)
+            submission.save!
+            expect_any_instance_of(MPI::Service).to receive(:find_profile_by_edipi).with(edipi: user.edipi)
+            expect_any_instance_of(MPI::Service).to receive(:find_profile_by_attributes).with(
+              first_name: user.first_name,
+              last_name: user.last_name,
+              ssn: user.ssn,
+              birth_date: user.birth_date
+            )
+            expect(Rails.logger).to receive(:info).with(no_icn_found_message, expected_log_payload)
+            account = submission.account
+            expect(account.icn).to be_nil
+          end
+        end
       end
     end
   end
diff --git a/spec/requests/v0/disability_compensation_form_spec.rb b/spec/requests/v0/disability_compensation_form_spec.rb
index f10e38c1947..3872a009c3c 100644
--- a/spec/requests/v0/disability_compensation_form_spec.rb
+++ b/spec/requests/v0/disability_compensation_form_spec.rb
@@ -8,7 +8,7 @@
 RSpec.describe 'V0::DisabilityCompensationForm', type: :request do
   include SchemaMatchers
 
-  let(:user) { build(:disabilities_compensation_user) }
+  let(:user) { build(:disabilities_compensation_user, :with_terms_of_use_agreement) }
   let(:headers) { { 'CONTENT_TYPE' => 'application/json' } }
   let(:headers_with_camel) { headers.merge('X-Key-Inflection' => 'camel') }
 
@@ -289,7 +289,10 @@ def build_optional_xx_dates
 
       context 'with an `bdd` claim' do
         let(:bdd_form) { File.read 'spec/support/disability_compensation_form/bdd_fe_submission.json' }
-        let(:user) { build(:disabilities_compensation_user, icn: '1012666073V986297') }
+        let(:user) do
+          build(:disabilities_compensation_user, :with_terms_of_use_agreement, icn: '1012666073V986297',
+                                                                               idme_uuid: SecureRandom.uuid)
+        end
 
         before do
           allow_any_instance_of(Auth::ClientCredentials::Service).to receive(:get_token).and_return('fake_token')
diff --git a/spec/sidekiq/central_mail/submit_form4142_job_spec.rb b/spec/sidekiq/central_mail/submit_form4142_job_spec.rb
index e8f8b83af46..30fcedc6d2e 100644
--- a/spec/sidekiq/central_mail/submit_form4142_job_spec.rb
+++ b/spec/sidekiq/central_mail/submit_form4142_job_spec.rb
@@ -22,7 +22,8 @@
       Flipper.disable(:disability_compensation_form4142_supplemental)
     end
 
-    let(:user) { create(:user, :loa3) }
+    let(:user_account) { user.user_account }
+    let(:user) { create(:user, :loa3, :with_terms_of_use_agreement) }
     let(:auth_headers) do
       EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
     end
@@ -35,6 +36,7 @@
       end
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json:,
@@ -120,6 +122,7 @@
       end
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: missing_postalcode_form_json,
@@ -138,7 +141,7 @@
 
     context 'catastrophic failure state' do
       describe 'when all retries are exhausted' do
-        let!(:form526_submission) { create(:form526_submission) }
+        let!(:form526_submission) { create(:form526_submission, user_account:) }
         let!(:form526_job_status) { create(:form526_job_status, :retryable_error, form526_submission:, job_id: 1) }
 
         it 'updates a StatsD counter and updates the status on an exhaustion event' do
@@ -172,7 +175,7 @@
                 timestamp: instance_of(Time),
                 form526_submission_id: form526_submission.id
               },
-              nil,
+              user_account.id,
               call_location: instance_of(Logging::CallLocation)
             )
 
@@ -201,7 +204,8 @@
       Flipper.enable(:disability_compensation_form4142_supplemental)
     end
 
-    let(:user) { create(:user, :loa3) }
+    let(:user_account) { user.user_account }
+    let(:user) { create(:user, :loa3, :with_terms_of_use_agreement) }
     let(:auth_headers) do
       EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
     end
@@ -214,6 +218,7 @@
       end
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json:,
@@ -349,6 +354,7 @@
       end
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: missing_postalcode_form_json,
diff --git a/spec/sidekiq/evss/disability_compensation_form/submit_form0781_spec.rb b/spec/sidekiq/evss/disability_compensation_form/submit_form0781_spec.rb
index 5d5d84fea5c..f78ad60b380 100644
--- a/spec/sidekiq/evss/disability_compensation_form/submit_form0781_spec.rb
+++ b/spec/sidekiq/evss/disability_compensation_form/submit_form0781_spec.rb
@@ -18,7 +18,8 @@
                                               anything).and_return(false)
   end
 
-  let(:user) { create(:user, :loa3) }
+  let(:user) { create(:user, :loa3, :with_terms_of_use_agreement) }
+  let(:user_account) { user.user_account }
   let(:auth_headers) do
     EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
   end
@@ -50,6 +51,7 @@
     context 'when a submission has both 0781 and 0781a' do
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: form0781,
@@ -99,6 +101,7 @@
     context 'when a submission has 0781v2' do
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: form0781v2,
@@ -148,7 +151,7 @@
 
   context 'catastrophic failure state' do
     describe 'when all retries are exhausted' do
-      let!(:form526_submission) { create(:form526_submission) }
+      let!(:form526_submission) { create(:form526_submission, user_account:) }
       let!(:form526_job_status) { create(:form526_job_status, :retryable_error, form526_submission:, job_id: 1) }
 
       it 'updates a StatsD counter and updates the status on an exhaustion event' do
@@ -184,7 +187,7 @@
               timestamp: instance_of(Time),
               form526_submission_id: form526_submission.id
             },
-            nil,
+            user_account.id,
             call_location: instance_of(Logging::CallLocation)
           )
 
@@ -307,6 +310,7 @@
 
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: form0781, # contains 0781 and 0781a
@@ -701,6 +705,7 @@
 
       let(:submission) do
         Form526Submission.create(user_uuid: user.uuid,
+                                 user_account:,
                                  auth_headers_json: auth_headers.to_json,
                                  saved_claim_id: saved_claim.id,
                                  form_json: form0781v2,
diff --git a/spec/sidekiq/evss/disability_compensation_form/submit_form526_all_claim_spec.rb b/spec/sidekiq/evss/disability_compensation_form/submit_form526_all_claim_spec.rb
index 9e005ad95ca..aa76eab73dc 100644
--- a/spec/sidekiq/evss/disability_compensation_form/submit_form526_all_claim_spec.rb
+++ b/spec/sidekiq/evss/disability_compensation_form/submit_form526_all_claim_spec.rb
@@ -25,7 +25,8 @@
       .and_return('fake_access_token')
   end
 
-  let(:user) { create(:user, :loa3) }
+  let(:user) { create(:user, :loa3, icn: '123498767V234859') }
+  let(:user_account) { create(:user_account, icn: user.icn, id: user.user_account_uuid) }
   let(:auth_headers) do
     EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
   end
@@ -35,10 +36,9 @@
 
     let(:saved_claim) { create(:va526ez) }
     let(:submitted_claim_id) { 600_130_094 }
-    let(:user_account) { create(:user_account, icn: '123498767V234859') }
     let(:submission) do
       create(:form526_submission,
-             user_account_id: user_account.id,
+             user_account:,
              user_uuid: user.uuid,
              auth_headers_json: auth_headers.to_json,
              saved_claim_id: saved_claim.id)
@@ -107,6 +107,7 @@ def submit_it
           create(:form526_submission,
                  :asthma_claim_for_increase,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -124,6 +125,7 @@ def submit_it
           create(:form526_submission,
                  :without_diagnostic_code,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -144,6 +146,7 @@ def submit_it
           create(:form526_submission,
                  :als_claim_for_increase,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -167,6 +170,7 @@ def submit_it
           create(:form526_submission,
                  :als_claim_for_increase_terminally_ill,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -195,6 +199,7 @@ def submit_it
         create(:form526_submission,
                :with_mixed_action_disabilities_and_free_text,
                user_uuid: user.uuid,
+               user_account:,
                auth_headers_json: auth_headers.to_json,
                saved_claim_id: saved_claim.id)
       end
@@ -214,6 +219,7 @@ def submit_it
             create(:form526_submission,
                    :without_diagnostic_code,
                    user_uuid: user.uuid,
+                   user_account:,
                    auth_headers_json: auth_headers.to_json,
                    saved_claim_id: saved_claim.id)
           end
@@ -296,6 +302,7 @@ def submit_it
           create(:form526_submission,
                  :with_empty_disabilities,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -350,6 +357,7 @@ def submit_it
           create(:form526_submission,
                  :non_rrd_with_mas_diagnostic_code,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -396,6 +404,7 @@ def submit_it
             create(:form526_submission,
                    :mas_diagnostic_code_with_classification,
                    user_uuid: user.uuid,
+                   user_account:,
                    auth_headers_json: auth_headers.to_json,
                    saved_claim_id: saved_claim.id)
           end
@@ -429,6 +438,7 @@ def submit_it
           create(:form526_submission,
                  :with_multiple_mas_diagnostic_code,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id)
         end
@@ -450,6 +460,7 @@ def submit_it
           create(:form526_submission,
                  :with_everything,
                  user_uuid: user.uuid,
+                 user_account:,
                  auth_headers_json: auth_headers.to_json,
                  saved_claim_id: saved_claim.id,
                  submit_endpoint: 'claims_api')
@@ -560,6 +571,7 @@ def submit_it
         create(:form526_submission,
                :with_uploads,
                user_uuid: user.uuid,
+               user_account:,
                auth_headers_json: auth_headers.to_json,
                saved_claim_id: saved_claim.id)
       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 b36392f9b35..4d62dcd2582 100644
--- a/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb
+++ b/spec/sidekiq/evss/disability_compensation_form/submit_uploads_spec.rb
@@ -12,7 +12,8 @@
     Flipper.disable(:form526_send_document_upload_failure_notification)
   end
 
-  let(:user) { create(:user, :loa3) }
+  let(:user) { create(:user, :loa3, :with_terms_of_use_agreement) }
+  let(:user_account) { user.user_account }
   let(:auth_headers) do
     EVSS::DisabilityCompensationAuthHeaders.new(user).add_headers(EVSS::AuthHeaders.new(user).to_h)
   end
@@ -20,6 +21,7 @@
   let(:submission) do
     create(:form526_submission, :with_uploads,
            user_uuid: user.uuid,
+           user_account:,
            auth_headers_json: auth_headers.to_json,
            saved_claim_id: saved_claim.id,
            submitted_claim_id: '600130094')
@@ -353,7 +355,7 @@
 
   context 'catastrophic failure state' do
     describe 'when all retries are exhausted' do
-      let!(:form526_submission) { create(:form526_submission, :with_uploads) }
+      let!(:form526_submission) { create(:form526_submission, :with_uploads, user_account:) }
       let!(:form526_job_status) { create(:form526_job_status, :retryable_error, form526_submission:, job_id: 1) }
 
       it 'updates a StatsD counter and updates the status on an exhaustion event' do
@@ -423,7 +425,7 @@
             timestamp: instance_of(Time),
             form526_submission_id: submission.id
           },
-          nil,
+          user_account.id,
           call_location: instance_of(Logging::CallLocation)
         )