diff --git a/.rubocop.yml b/.rubocop.yml
index edd745f80..df06cf101 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -27,9 +27,6 @@ Rails/EnvironmentComparison:
 Rails/Exit:
   Enabled: true
 
-Rails/FindBy:
-  Enabled: true
-
 Rails/FindEach:
   Enabled: true
 
diff --git a/.rubocop_basic.yml b/.rubocop_basic.yml
index 81e130604..94d7c4916 100644
--- a/.rubocop_basic.yml
+++ b/.rubocop_basic.yml
@@ -156,6 +156,13 @@ Rails/ApplicationRecord:
 Rails/Date:
   Enabled: true
 
+Rails/DynamicFindBy:
+  Enabled: true
+  Severity: refactor
+
+Rails/FindBy:
+  Enabled: true
+
 Rails/HttpPositionalArguments:
   Enabled: true
 
diff --git a/app/models/budget/ballot.rb b/app/models/budget/ballot.rb
index 9539119b0..f184e63a0 100644
--- a/app/models/budget/ballot.rb
+++ b/app/models/budget/ballot.rb
@@ -68,7 +68,7 @@ class Budget
 
     def heading_for_group(group)
       return nil unless has_lines_in_group?(group)
-      investments.where(group: group).first.heading
+      investments.find_by(group: group).heading
     end
 
     def casted_offline?
diff --git a/app/models/budget/phase.rb b/app/models/budget/phase.rb
index 859beb51f..c13a7825c 100644
--- a/app/models/budget/phase.rb
+++ b/app/models/budget/phase.rb
@@ -30,7 +30,7 @@ class Budget
     scope :published,         -> { enabled.where.not(kind: "drafting") }
 
     PHASE_KINDS.each do |phase|
-      define_singleton_method(phase) { find_by_kind(phase) }
+      define_singleton_method(phase) { find_by(kind: phase) }
     end
 
     def next_enabled_phase
diff --git a/app/models/concerns/relationable.rb b/app/models/concerns/relationable.rb
index 4ce6bd3d3..85f396ebb 100644
--- a/app/models/concerns/relationable.rb
+++ b/app/models/concerns/relationable.rb
@@ -6,7 +6,7 @@ module Relationable
   end
 
   def find_related_content(relationable)
-    RelatedContent.where(parent_relationable: self, child_relationable: relationable).first
+    RelatedContent.find_by(parent_relationable: self, child_relationable: relationable)
   end
 
   def relationed_contents
diff --git a/app/models/concerns/sluggable.rb b/app/models/concerns/sluggable.rb
index bdcdff856..7f9bff56b 100644
--- a/app/models/concerns/sluggable.rb
+++ b/app/models/concerns/sluggable.rb
@@ -5,11 +5,11 @@ module Sluggable
     before_validation :generate_slug, if: :generate_slug?
 
     def self.find_by_slug_or_id(slug_or_id)
-      find_by_slug(slug_or_id) || find_by_id(slug_or_id)
+      find_by(slug: slug_or_id) || find_by(id: slug_or_id)
     end
 
     def self.find_by_slug_or_id!(slug_or_id)
-      find_by_slug(slug_or_id) || find(slug_or_id)
+      find_by(slug: slug_or_id) || find(slug_or_id)
     end
   end
 
diff --git a/app/models/legislation/question.rb b/app/models/legislation/question.rb
index 91b542d4b..d28029305 100644
--- a/app/models/legislation/question.rb
+++ b/app/models/legislation/question.rb
@@ -30,7 +30,7 @@ class Legislation::Question < ApplicationRecord
   end
 
   def answer_for_user(user)
-    answers.where(user: user).first
+    answers.find_by(user: user)
   end
 
   def comments_for_verified_residents_only?
diff --git a/app/models/newsletter.rb b/app/models/newsletter.rb
index e6fcf7720..021c8c7a8 100644
--- a/app/models/newsletter.rb
+++ b/app/models/newsletter.rb
@@ -62,7 +62,7 @@ class Newsletter < ApplicationRecord
     end
 
     def log_delivery(recipient_email)
-      user = User.where(email: recipient_email).first
+      user = User.find_by(email: recipient_email)
       Activity.log(user, :email, self)
     end
 end
diff --git a/app/models/notification.rb b/app/models/notification.rb
index 66343ae6a..e295c736c 100644
--- a/app/models/notification.rb
+++ b/app/models/notification.rb
@@ -45,7 +45,7 @@ class Notification < ApplicationRecord
   end
 
   def self.existent(user, notifiable)
-    unread.where(user: user, notifiable: notifiable).first
+    unread.find_by(user: user, notifiable: notifiable)
   end
 
   def notifiable_action
diff --git a/app/models/officing/residence.rb b/app/models/officing/residence.rb
index 7e61a0062..7ec430005 100644
--- a/app/models/officing/residence.rb
+++ b/app/models/officing/residence.rb
@@ -69,8 +69,7 @@ class Officing::Residence
   end
 
   def find_user_by_document
-    User.where(document_number: document_number,
-               document_type:   document_type).first
+    User.find_by(document_number: document_number, document_type: document_type)
   end
 
   def residence_in_madrid
@@ -96,7 +95,7 @@ class Officing::Residence
   end
 
   def geozone
-    Geozone.where(census_code: district_code).first
+    Geozone.find_by(census_code: district_code)
   end
 
   def district_code
diff --git a/app/models/poll/ballot.rb b/app/models/poll/ballot.rb
index 09cbf5916..55500cf02 100644
--- a/app/models/poll/ballot.rb
+++ b/app/models/poll/ballot.rb
@@ -22,11 +22,11 @@ class Poll::Ballot < ApplicationRecord
   end
 
   def ballot
-    Budget::Ballot.where(poll_ballot: self).first
+    Budget::Ballot.find_by(poll_ballot: self)
   end
 
   def find_investment(investment_id)
-    ballot.budget.investments.where(id: investment_id).first
+    ballot.budget.investments.find_by(id: investment_id)
   end
 
   def not_already_added?(investment)
diff --git a/app/models/poll/booth.rb b/app/models/poll/booth.rb
index 64174a7a6..d253c5c09 100644
--- a/app/models/poll/booth.rb
+++ b/app/models/poll/booth.rb
@@ -23,7 +23,7 @@ class Poll
     end
 
     def assignment_on_poll(poll)
-      booth_assignments.where(poll: poll).first
+      booth_assignments.find_by(poll: poll)
     end
   end
 end
diff --git a/app/models/poll/voter.rb b/app/models/poll/voter.rb
index d079ea991..8b6b79fd2 100644
--- a/app/models/poll/voter.rb
+++ b/app/models/poll/voter.rb
@@ -56,7 +56,7 @@ class Poll
       def fill_stats_fields
         if in_census?
           self.gender = census_api_response.gender
-          self.geozone_id = Geozone.select(:id).where(census_code: census_api_response.district_code).first&.id
+          self.geozone_id = Geozone.select(:id).find_by(census_code: census_api_response.district_code)&.id
           self.age = voter_age(census_api_response.date_of_birth)
         end
       end
diff --git a/app/models/setting.rb b/app/models/setting.rb
index db0b6645c..a63cda9ac 100644
--- a/app/models/setting.rb
+++ b/app/models/setting.rb
@@ -35,7 +35,7 @@ class Setting < ApplicationRecord
     end
 
     def []=(key, value)
-      setting = where(key: key).first || new(key: key)
+      setting = find_by(key: key) || new(key: key)
       setting.value = value.presence
       setting.save!
       value
@@ -50,7 +50,7 @@ class Setting < ApplicationRecord
     end
 
     def remove(key)
-      setting = where(key: key).first
+      setting = find_by(key: key)
       setting.destroy if setting.present?
     end
 
diff --git a/app/models/signature.rb b/app/models/signature.rb
index 8395e7cca..2c70db00b 100644
--- a/app/models/signature.rb
+++ b/app/models/signature.rb
@@ -36,7 +36,7 @@ class Signature < ApplicationRecord
   end
 
   def assign_signature_to_vote
-    vote = Vote.where(votable: signable, voter: user).first
+    vote = Vote.find_by(votable: signable, voter: user)
     vote&.update!(signature: self)
   end
 
@@ -55,7 +55,7 @@ class Signature < ApplicationRecord
       email: nil,
       date_of_birth: @census_api_response.date_of_birth,
       gender: @census_api_response.gender,
-      geozone: Geozone.where(census_code: @census_api_response.district_code).first
+      geozone: Geozone.find_by(census_code: @census_api_response.district_code)
     }
     User.create!(user_params)
   end
@@ -84,7 +84,7 @@ class Signature < ApplicationRecord
   end
 
   def set_user
-    user = User.where(document_number: document_number).first
+    user = User.find_by(document_number: document_number)
     update(user: user)
   end
 
diff --git a/app/models/user.rb b/app/models/user.rb
index c1f032781..a6abde504 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -237,8 +237,8 @@ class User < ApplicationRecord
   end
 
   def take_votes_if_erased_document(document_number, document_type)
-    erased_user = User.erased.where(document_number: document_number)
-                             .where(document_type: document_type).first
+    erased_user = User.erased.find_by(document_number: document_number,
+                                      document_type: document_type)
     if erased_user.present?
       take_votes_from(erased_user)
       erased_user.update!(document_number: nil, document_type: nil)
@@ -345,8 +345,8 @@ class User < ApplicationRecord
   def self.find_for_database_authentication(warden_conditions)
     conditions = warden_conditions.dup
     login = conditions.delete(:login)
-    where(conditions.to_hash).where(["lower(email) = ?", login.downcase]).first ||
-    where(conditions.to_hash).where(["username = ?", login]).first
+    where(conditions.to_hash).find_by(["lower(email) = ?", login.downcase]) ||
+    where(conditions.to_hash).find_by(["username = ?", login])
   end
 
   def self.find_by_manager_login(manager_login)
diff --git a/app/models/verification/email.rb b/app/models/verification/email.rb
index 2a4815279..91b981f24 100644
--- a/app/models/verification/email.rb
+++ b/app/models/verification/email.rb
@@ -19,7 +19,7 @@ class Verification::Email
   end
 
   def user
-    User.where(document_number: verified_user.document_number).first
+    User.find_by(document_number: verified_user.document_number)
   end
 
   def generate_token
diff --git a/app/models/verification/management/email.rb b/app/models/verification/management/email.rb
index b538d0505..dd3111222 100644
--- a/app/models/verification/management/email.rb
+++ b/app/models/verification/management/email.rb
@@ -13,7 +13,7 @@ class Verification::Management::Email
   delegate :username, to: :user, allow_nil: true
 
   def user
-    @user ||= User.where(email: email).first
+    @user ||= User.find_by(email: email)
   end
 
   def user?
diff --git a/app/models/verification/residence.rb b/app/models/verification/residence.rb
index eaa56ca42..c33de983d 100644
--- a/app/models/verification/residence.rb
+++ b/app/models/verification/residence.rb
@@ -61,7 +61,7 @@ class Verification::Residence
   end
 
   def geozone
-    Geozone.where(census_code: district_code).first
+    Geozone.find_by(census_code: district_code)
   end
 
   def district_code
diff --git a/app/models/widget/feed.rb b/app/models/widget/feed.rb
index 775048860..4dfce59f4 100644
--- a/app/models/widget/feed.rb
+++ b/app/models/widget/feed.rb
@@ -8,7 +8,7 @@ class Widget::Feed < ApplicationRecord
   end
 
   def setting
-    Setting.where(key: "homepage.widgets.feeds.#{kind}").first
+    Setting.find_by(key: "homepage.widgets.feeds.#{kind}")
   end
 
   def self.active
diff --git a/config/initializers/i18n_translation.rb b/config/initializers/i18n_translation.rb
index aa500468c..aae984e1f 100644
--- a/config/initializers/i18n_translation.rb
+++ b/config/initializers/i18n_translation.rb
@@ -9,7 +9,7 @@ module ActionView
       def t(key, options = {})
         current_locale = options[:locale].presence || I18n.locale
 
-        i18_content = I18nContent.find_by_key(key)
+        i18_content = I18nContent.find_by(key: key)
         translation = I18nContentTranslation.where(i18n_content_id: i18_content&.id,
                                                    locale: current_locale).first&.value
         translation.presence || translate(key, options)
diff --git a/db/pages/accessibility.rb b/db/pages/accessibility.rb
index 5741a57cc..006368164 100644
--- a/db/pages/accessibility.rb
+++ b/db/pages/accessibility.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("accessibility").nil?
+if SiteCustomization::Page.find_by(slug: "accessibility").nil?
   page = SiteCustomization::Page.new(slug: "accessibility", status: "published")
   page.title = I18n.t("pages.accessibility.title")
 
diff --git a/db/pages/conditions.rb b/db/pages/conditions.rb
index 8a57b63cc..c47216b51 100644
--- a/db/pages/conditions.rb
+++ b/db/pages/conditions.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("conditions").nil?
+if SiteCustomization::Page.find_by(slug: "conditions").nil?
   page = SiteCustomization::Page.new(slug: "conditions", status: "published")
   page.print_content_flag = true
   page.title = I18n.t("pages.conditions.title")
diff --git a/db/pages/faq.rb b/db/pages/faq.rb
index 6479e1b57..3e960ae14 100644
--- a/db/pages/faq.rb
+++ b/db/pages/faq.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("faq").nil?
+if SiteCustomization::Page.find_by(slug: "faq").nil?
   page = SiteCustomization::Page.new(slug: "faq", status: "published")
   page.title = I18n.t("pages.help.faq.page.title")
   page.content = "<p>#{I18n.t("pages.help.faq.page.description")}</p>"
diff --git a/db/pages/privacy.rb b/db/pages/privacy.rb
index f06b1687c..71e79880a 100644
--- a/db/pages/privacy.rb
+++ b/db/pages/privacy.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("privacy").nil?
+if SiteCustomization::Page.find_by(slug: "privacy").nil?
   page = SiteCustomization::Page.new(slug: "privacy", status: "published")
   page.print_content_flag = true
   page.title = I18n.t("pages.privacy.title")
diff --git a/db/pages/welcome_level_three_verified.rb b/db/pages/welcome_level_three_verified.rb
index 2c00e4fb0..8c2caaaac 100644
--- a/db/pages/welcome_level_three_verified.rb
+++ b/db/pages/welcome_level_three_verified.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_level_three_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_level_three_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_level_three_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 
diff --git a/db/pages/welcome_level_two_verified.rb b/db/pages/welcome_level_two_verified.rb
index 911a0c850..a459a6fa6 100644
--- a/db/pages/welcome_level_two_verified.rb
+++ b/db/pages/welcome_level_two_verified.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_level_two_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_level_two_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_level_two_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 
diff --git a/db/pages/welcome_not_verified.rb b/db/pages/welcome_not_verified.rb
index 51df2ac39..3ff99142d 100644
--- a/db/pages/welcome_not_verified.rb
+++ b/db/pages/welcome_not_verified.rb
@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_not_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_not_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_not_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 
diff --git a/spec/features/admin/site_customization/pages_spec.rb b/spec/features/admin/site_customization/pages_spec.rb
index 4be5819c4..17b619659 100644
--- a/spec/features/admin/site_customization/pages_spec.rb
+++ b/spec/features/admin/site_customization/pages_spec.rb
@@ -25,7 +25,7 @@ describe "Admin custom pages" do
 
       expect(SiteCustomization::Page.count).to be 7
       slugs.each do |slug|
-        expect(SiteCustomization::Page.find_by_slug(slug).status).to eq "published"
+        expect(SiteCustomization::Page.find_by(slug: slug).status).to eq "published"
       end
 
       expect(all("[id^='site_customization_page_']").count).to be 7