diff --git a/app/models/wizards/steps/signup/sektion/family_fields/member.rb b/app/models/wizards/steps/signup/sektion/family_fields/member.rb
index 9c6d417c5..279f0ed31 100644
--- a/app/models/wizards/steps/signup/sektion/family_fields/member.rb
+++ b/app/models/wizards/steps/signup/sektion/family_fields/member.rb
@@ -39,7 +39,7 @@ def adult?
     private
 
     def assert_email_unique
-      if emails.include?(email)
+      if emails.include?(email) || Person.exists?(email: email)
         errors.add(:email, :taken)
       end
       emails.push(email)
diff --git a/spec/models/wizards/signup/sektion_wizard_spec.rb b/spec/models/wizards/signup/sektion_wizard_spec.rb
index 6307921b9..dc6ad1418 100644
--- a/spec/models/wizards/signup/sektion_wizard_spec.rb
+++ b/spec/models/wizards/signup/sektion_wizard_spec.rb
@@ -80,6 +80,32 @@ def build(params = required_attrs)
       ]
     end
 
+    it "is invalid when on family_fields step and resuses main person email" do
+      @current_step = 2
+      required_attrs[:family_fields] = {
+        members_attributes: [
+          [0, {first_name: "Maxine", last_name: "Muster", birthday: "1.1.2000", email: "max.muster@example.com"}]
+        ]
+      }
+      expect(wizard).not_to be_valid
+      expect(wizard.errors).to be_empty
+      expect(wizard.family_fields).not_to be_valid
+      expect(wizard.family_fields.members.first.errors.full_messages).to eq ["E-Mail (optional) ist bereits vergeben. Die E-Mail muss eindeutig sein pro Person."]
+    end
+
+    it "is invalid when on family_fields step and uses existing email" do
+      @current_step = 2
+      required_attrs[:family_fields] = {
+        members_attributes: [
+          [0, {first_name: "Maxine", last_name: "Muster", birthday: "1.1.2000", email: "e.hillary@hitobito.example.com"}]
+        ]
+      }
+      expect(wizard).not_to be_valid
+      expect(wizard.errors).to be_empty
+      expect(wizard.family_fields).not_to be_valid
+      expect(wizard.family_fields.members.first.errors.full_messages).to eq ["E-Mail (optional) ist bereits vergeben. Die E-Mail muss eindeutig sein pro Person."]
+    end
+
     it "is invalid when on various_fields step and data_protection is blank" do
       @current_step = 3
       required_attrs[:various_fields] = {data_protection: nil}
diff --git a/spec/models/wizards/steps/signup/sektion/family_fields_spec.rb b/spec/models/wizards/steps/signup/sektion/family_fields_spec.rb
index c2595a88b..90edc5151 100644
--- a/spec/models/wizards/steps/signup/sektion/family_fields_spec.rb
+++ b/spec/models/wizards/steps/signup/sektion/family_fields_spec.rb
@@ -74,6 +74,15 @@
         expect(form.errors.full_messages).to eq ["In einer Familienmitgliedschaft sind maximal 2 Erwachsene inbegriffen."]
       end
 
+      it "is invalid if second member reuses existing email" do
+        form.members_attributes = [
+          [0, required_attrs.merge(email: "acceptable@example.com")],
+          [1, required_attrs.merge(email: "e.hillary@hitobito.example.com", birthday: "1.10.2014")]
+        ]
+        expect(form).not_to be_valid
+        expect(form.members.second.errors.full_messages).to eq ["E-Mail (optional) ist bereits vergeben. Die E-Mail muss eindeutig sein pro Person."]
+      end
+
       it "is invalid if second member reuses main_email in members" do
         form.members_attributes = [
           [0, required_attrs.merge(email: "acceptable@example.com")],