diff --git a/modules/check_in/spec/services/check_in/vaos/base_service_spec.rb b/modules/check_in/spec/services/check_in/vaos/base_service_spec.rb
new file mode 100644
index 00000000000..f523aab9fc6
--- /dev/null
+++ b/modules/check_in/spec/services/check_in/vaos/base_service_spec.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe CheckIn::VAOS::BaseService do
+  subject { described_class.new(patient_icn:) }
+
+  let(:patient_icn) { '123' }
+  let(:token) { 'test_token' }
+  let(:request_id) { SecureRandom.uuid }
+
+  describe '#config' do
+    it 'returns an instance of Configuration' do
+      expect(subject.config).to be_an_instance_of(CheckIn::VAOS::Configuration)
+    end
+  end
+
+  describe '#headers' do
+    before do
+      allow_any_instance_of(CheckIn::Map::TokenService).to receive(:token).and_return(token)
+      RequestStore.store['request_id'] = request_id
+    end
+
+    it 'returns correct headers' do
+      expect(subject.headers).to eq({ 'Referer' => 'https://review-instance.va.gov',
+                                      'X-VAMF-JWT' => token,
+                                      'X-Request-ID' => request_id })
+    end
+  end
+
+  describe '#referrer' do
+    context 'when ends in .gov' do
+      it 'returns the hostname with "vets" replaced with "va"' do
+        allow(Settings).to receive(:hostname).and_return('veteran.apps.vets.gov')
+        expect(subject.referrer).to eq('https://veteran.apps.va.gov')
+      end
+    end
+
+    context 'when does not end in .gov' do
+      it 'returns https://review-instance.va.gov' do
+        expect(subject.referrer).to eq('https://review-instance.va.gov')
+      end
+    end
+  end
+end