diff --git a/app/models/user.rb b/app/models/user.rb
index 1733aeb7d..962937e45 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -269,7 +269,14 @@ class User < ApplicationRecord
   end
 
   def valid_for_authentication?
-    super && active?
+    super && account_is_active?
+  end
+
+  def account_is_active?
+    unless active?
+      throw(:warden, message: :inactive_account)
+    end
+    true
   end
 
   def editable_duplicate_lettings_logs_sets
diff --git a/config/locales/devise.en.yml b/config/locales/devise.en.yml
index 58d68497c..d5d50b5f9 100644
--- a/config/locales/devise.en.yml
+++ b/config/locales/devise.en.yml
@@ -16,6 +16,7 @@ en:
       timeout: "Your session expired. Sign in again to continue."
       unauthenticated: "You need to sign in or sign up before continuing."
       unconfirmed: "You must confirm your email address before continuing."
+      inactive_account: "Your account has been deactivated. Ask a data coordinator at your organisation to reactivate your account. Contact the helpdesk if you don't know who your data coordinator is."
     mailer:
       confirmation_instructions:
         subject: "Confirmation instructions."