diff --git a/app/logical/bulk_update_request_processor.rb b/app/logical/bulk_update_request_processor.rb
index 741e8f38b..7e3a8e7b2 100644
--- a/app/logical/bulk_update_request_processor.rb
+++ b/app/logical/bulk_update_request_processor.rb
@@ -50,6 +50,10 @@ class BulkUpdateRequestProcessor
         [:change_category, Tag.normalize_name($1), $2.downcase]
       when /\Anuke (\S+)\z/i
         [:nuke, $1]
+      when /\Adeprecate (\S+)\z/i
+        [:deprecate, $1]
+      when /\Aundeprecate (\S+)\z/i
+        [:undeprecate, $1]
       else
         [:invalid_line, line]
       end
@@ -125,6 +129,18 @@ class BulkUpdateRequestProcessor
         when :nuke
           # okay
 
+        when :deprecate
+          tag = Tag.find_by_name(args[0])
+          if tag.is_deprecated?
+            errors.add(:base, "Can't deprecate #{args[0]} (tag is already deprecated)")
+          end
+
+        when :undeprecate
+          tag = Tag.find_by_name(args[0])
+          if !tag.is_deprecated?
+            errors.add(:base, "Can't undeprecate #{args[0]} (tag is not deprecated)")
+          end
+
         when :invalid_line
           errors.add(:base, "Invalid line: #{args[0]}")
 
@@ -182,6 +198,16 @@ class BulkUpdateRequestProcessor
           tag = Tag.find_or_create_by_name(args[0])
           tag.update!(category: Tag.categories.value_for(args[1]))
 
+        when :deprecate
+          tag = Tag.find_or_create_by_name(args[0])
+          tag.update!(is_deprecated: true)
+          TagImplication.active.where(consequent_name: tag.name).each { |ti| ti.reject!(User.system) }
+          TagImplication.active.where(antecedent_name: tag.name).each { |ti| ti.reject!(User.system) }
+
+        when :undeprecate
+          tag = Tag.find_or_create_by_name(args[0])
+          tag.update!(is_deprecated: false)
+
         else
           # should never happen
           raise Error, "Unknown command: #{command}"
@@ -204,7 +230,7 @@ class BulkUpdateRequestProcessor
         [args[0], args[1]]
       when :mass_update
         PostQuery.new(args[0]).tag_names + PostQuery.new(args[1]).tag_names
-      when :nuke
+      when :nuke, :deprecate, :undeprecate
         PostQuery.new(args[0]).tag_names
       when :change_category
         args[0]
@@ -240,6 +266,8 @@ class BulkUpdateRequestProcessor
         else
           "nuke {{#{args[0]}}}"
         end
+      when :deprecate, :undeprecate
+        "#{command.to_s} [[#{args[0]}]]"
       when :change_category
         "category [[#{args[0]}]] -> #{args[1]}"
       else
diff --git a/app/models/mod_action.rb b/app/models/mod_action.rb
index a305e665f..4978e0c0e 100644
--- a/app/models/mod_action.rb
+++ b/app/models/mod_action.rb
@@ -60,6 +60,8 @@ class ModAction < ApplicationRecord
     tag_implication_create: 140,
     tag_implication_update: 141, # XXX unused
     tag_implication_delete: 142,
+    tag_deprecate: 240,
+    tag_undeprecate: 242,
     ip_ban_create: 160,
     ip_ban_delete: 162,
     ip_ban_undelete: 163,
diff --git a/app/models/post.rb b/app/models/post.rb
index e629a9e61..9f981b194 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -411,6 +411,7 @@ class Post < ApplicationRecord
       normalized_tags = Tag.convert_cosplay_tags(normalized_tags)
       normalized_tags += Tag.create_for_list(Tag.automatic_tags_for(normalized_tags))
       normalized_tags += TagImplication.tags_implied_by(normalized_tags).map(&:name)
+      normalized_tags -= added_deprecated_tags
       normalized_tags = normalized_tags.compact.uniq.sort
       normalized_tags = Tag.create_for_list(normalized_tags)
       self.tag_string = normalized_tags.join(" ")
@@ -428,6 +429,16 @@ class Post < ApplicationRecord
       tag_names - invalid_tags.map(&:name)
     end
 
+    def added_deprecated_tags
+      added_deprecated_tags = added_tags.select(&:is_deprecated)
+      if added_deprecated_tags.present?
+        added_deprecated_tags_list = added_deprecated_tags.map { |t| "[[#{t.name}]]" }.to_sentence
+        warnings.add(:base, "The following tags are deprecated and could not be added: #{added_deprecated_tags_list}")
+      end
+
+      added_deprecated_tags.pluck(:name)
+    end
+
     def remove_negated_tags(tags)
       @negated_tags, tags = tags.partition {|x| x =~ /\A-/i}
       @negated_tags = @negated_tags.map {|x| x[1..-1]}
diff --git a/app/models/tag.rb b/app/models/tag.rb
index 402953306..3114ffbaa 100644
--- a/app/models/tag.rb
+++ b/app/models/tag.rb
@@ -16,6 +16,7 @@ class Tag < ApplicationRecord
   validates :category, inclusion: { in: TagCategory.category_ids }
 
   before_create :create_character_tag_for_cosplay_tag, if: :is_cosplay_tag?
+  before_save :create_mod_action
   after_save :update_category_cache, if: :saved_change_to_category?
   after_save :update_category_post_counts, if: :saved_change_to_category?
 
@@ -217,6 +218,17 @@ class Tag < ApplicationRecord
     end
   end
 
+  concerning :DeprecationMethods do
+    def create_mod_action
+      return if CurrentUser.user == User.system
+      if is_deprecated_was == true and is_deprecated == false
+        ModAction.log("marked the tag [[#{name}]] as not deprecated", :tag_undeprecate)
+      elsif is_deprecated_was == false and is_deprecated == true
+        ModAction.log("marked the tag [[#{name}]] as deprecated", :tag_deprecate)
+      end
+    end
+  end
+
   module SearchMethods
     def autocorrect_matches(name)
       fuzzy_name_matches(name).order_similarity(name)
@@ -265,7 +277,7 @@ class Tag < ApplicationRecord
     end
 
     def search(params)
-      q = search_attributes(params, :id, :created_at, :updated_at, :category, :post_count, :name, :wiki_page, :artist, :antecedent_alias, :consequent_aliases, :antecedent_implications, :consequent_implications, :dtext_links)
+      q = search_attributes(params, :id, :created_at, :updated_at, :is_deprecated, :category, :post_count, :name, :wiki_page, :artist, :antecedent_alias, :consequent_aliases, :antecedent_implications, :consequent_implications, :dtext_links)
 
       if params[:fuzzy_name_matches].present?
         q = q.fuzzy_name_matches(params[:fuzzy_name_matches])
diff --git a/app/policies/tag_policy.rb b/app/policies/tag_policy.rb
index 563279321..e299ac8f9 100644
--- a/app/policies/tag_policy.rb
+++ b/app/policies/tag_policy.rb
@@ -7,7 +7,14 @@ class TagPolicy < ApplicationPolicy
       (user.is_member? && record.post_count < 50)
   end
 
+  def can_change_deprecated_status?
+    user.is_admin? || (record.post_count == 0 && !record.is_deprecated?)
+  end
+
   def permitted_attributes
-    [(:category if can_change_category?)].compact
+    [
+      (:category if can_change_category?),
+      (:is_deprecated if can_change_deprecated_status?),
+    ].compact
   end
 end
diff --git a/app/views/posts/index.html.erb b/app/views/posts/index.html.erb
index e3224bac0..3653efbe8 100644
--- a/app/views/posts/index.html.erb
+++ b/app/views/posts/index.html.erb
@@ -121,6 +121,10 @@
           <%= format_text(wiki_page.body) %>
           <%= render "tag_relationships/alias_and_implication_list", tag: wiki_page.tag %>
 
+          <% if wiki_page.tag&.is_deprecated? %>
+            <p class="fineprint">This tag is <%= link_to "deprecated", wiki_page_path("help:deprecation_notice") %> and can't be added to new posts.</p>
+          <% end %>
+
           <p class="mt-4">
             <%= link_to_wiki "View wiki", wiki_page.title, id: "view-wiki-link" %>
           </p>
@@ -154,6 +158,10 @@
       <p>There is no wiki page yet for the tag <%= link_to_wiki @post_set.tag.pretty_name %>. <%= link_to "Create new wiki page", new_wiki_page_path(wiki_page: { title: @post_set.tag.name }), rel: "nofollow" %>.</p>
 
       <%= render "tag_relationships/alias_and_implication_list", tag: @post_set.tag %>
+
+      <% if @post_set.tag&.is_deprecated? %>
+        <p class="fineprint">This tag is <%= link_to "deprecated", wiki_page_path("help:deprecation_notice") %> and can't be added to new posts.</p>
+      <% end %>
     <% end %>
   </div>
 
diff --git a/app/views/tags/_search.html.erb b/app/views/tags/_search.html.erb
index 8c57dc61e..32729a8bd 100644
--- a/app/views/tags/_search.html.erb
+++ b/app/views/tags/_search.html.erb
@@ -2,6 +2,7 @@
   <%= f.input :name_or_alias_matches, label: "Name", input_html: { value: params[:search][:name_or_alias_matches], data: { autocomplete: "tag" } } %>
   <%= f.input :category, label: "Category", collection: TagCategory.canonical_mapping.to_a, include_blank: true,selected: params[:search][:category] %>
   <%= f.input :order, collection: [%w[Newest date], %w[Count count], %w[Name name]], include_blank: false, selected: params[:search][:order] %>
+  <%= f.input :is_deprecated, label: "Is deprecated?", collection: %w[yes no], include_blank: true, selected: params[:search][:is_deprecated] %>
   <%= f.input :hide_empty, label: "Hide empty?", collection: %w[yes no], selected: params[:search][:hide_empty] %>
   <%= f.input :has_wiki_page, label: "Has wiki?", collection: %w[yes no], include_blank: true, selected: params[:search][:has_wiki_page] %>
   <%= f.input :has_artist, label: "Has artist?", collection: %w[yes no], include_blank: true, selected: params[:search][:has_artist] %>
diff --git a/app/views/tags/edit.html.erb b/app/views/tags/edit.html.erb
index 6cb39264c..0929dbd45 100644
--- a/app/views/tags/edit.html.erb
+++ b/app/views/tags/edit.html.erb
@@ -5,10 +5,20 @@
     <%= edit_form_for(@tag) do |f| %>
       <% if policy(@tag).can_change_category? %>
         <%= f.input :category, collection: TagCategory.canonical_mapping.to_a, include_blank: false %>
-        <%= f.button :submit, "Submit" %>
       <% else %>
         <p>Create a <%= link_to "bulk update request", new_bulk_update_request_path(bulk_update_request: { script: "category #{@tag.name} -> general" }) %> to change this tag's category.</p>
       <% end %>
+
+      <% if policy(@tag).can_change_deprecated_status? %>
+        <%= f.input :is_deprecated, :collection => [["No", "false"], ["Yes", "true"]], :include_blank => false %>
+      <% else %>
+        <% if @tag.is_deprecated? %>
+        <p>Create a <%= link_to "bulk update request", new_bulk_update_request_path(bulk_update_request: { script: "deprecate #{@tag.name}" }) %> to mark this tag as not deprecated.</p>
+        <% else %>
+        <p>Create a <%= link_to "bulk update request", new_bulk_update_request_path(bulk_update_request: { script: "undeprecate #{@tag.name}" }) %> to mark this tag as deprecated.</p>
+        <% end %>
+      <% end %>
+      <%= f.button :submit, "Submit" %>
     <% end %>
   </div>
 </div>
diff --git a/app/views/tags/show.html.erb b/app/views/tags/show.html.erb
index cc65cfb23..ab7908481 100644
--- a/app/views/tags/show.html.erb
+++ b/app/views/tags/show.html.erb
@@ -8,6 +8,9 @@
     <ul>
       <li>Count: <%= @tag.post_count %></li>
       <li>Category: <%= @tag.category_name %></li>
+      <% if @tag.is_deprecated? %>
+        <li> This tag is <%= link_to "deprecated", wiki_page_path("help:deprecation_notice") %> and can't be added to new posts.</li>
+      <% end %>
     </ul>
   </div>
 </div>
diff --git a/app/views/wiki_pages/new.html.erb b/app/views/wiki_pages/new.html.erb
index f5077534b..09ce961c3 100644
--- a/app/views/wiki_pages/new.html.erb
+++ b/app/views/wiki_pages/new.html.erb
@@ -18,6 +18,11 @@
   <% end %>
 
   <%= render "tag_relationships/alias_and_implication_list", tag: @wiki_page.tag %>
+
+  <% if @wiki_page.tag&.is_deprecated? %>
+    <p class="fineprint">This tag is <%= link_to "deprecated", wiki_page_path("help:deprecation_notice") %> and can't be added to new posts.</p>
+  <% end %>
+
   <%= render "wiki_pages/posts", wiki_page: @wiki_page %>
 <% end %>
 
diff --git a/app/views/wiki_pages/show.html.erb b/app/views/wiki_pages/show.html.erb
index e2cdcf11d..d3d01eaa2 100644
--- a/app/views/wiki_pages/show.html.erb
+++ b/app/views/wiki_pages/show.html.erb
@@ -37,6 +37,10 @@
     <% end %>
 
     <%= render "tag_relationships/alias_and_implication_list", tag: @wiki_page.tag %>
+
+    <% if @wiki_page.tag&.is_deprecated? %>
+      <p class="fineprint">This tag is <%= link_to "deprecated", wiki_page_path("help:deprecation_notice") %> and can't be added to new posts.</p>
+    <% end %>
   </div>
 
   <%= render "wiki_pages/posts", wiki_page: @wiki_page %>
diff --git a/db/migrate/20220407203236_add_is_deprecated_to_tags.rb b/db/migrate/20220407203236_add_is_deprecated_to_tags.rb
new file mode 100644
index 000000000..5ae53c4d5
--- /dev/null
+++ b/db/migrate/20220407203236_add_is_deprecated_to_tags.rb
@@ -0,0 +1,7 @@
+class AddIsDeprecatedToTags < ActiveRecord::Migration[7.0]
+  def change
+    ApplicationRecord.without_timeout do
+      add_column :tags, :is_deprecated, :boolean, null: false, default: false
+    end
+  end
+end
diff --git a/db/structure.sql b/db/structure.sql
index 109fa33b5..181769d4b 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -5796,6 +5796,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20220211075129'),
 ('20220318082614'),
 ('20220403042706'),
-('20220403220558');
+('20220403220558'),
+('20220407203236');
 
 
diff --git a/test/functional/tags_controller_test.rb b/test/functional/tags_controller_test.rb
index 266e0cd1b..58e2b5fea 100644
--- a/test/functional/tags_controller_test.rb
+++ b/test/functional/tags_controller_test.rb
@@ -119,6 +119,51 @@ class TagsControllerTest < ActionDispatch::IntegrationTest
         end
       end
 
+      context "for deprecation" do
+        setup do
+          @deprecated_tag = create(:tag, name: "bad_tag", category: Tag.categories.general, post_count: 0, is_deprecated: true)
+          @nondeprecated_tag = create(:tag, name: "log", category: Tag.categories.general, post_count: 0)
+          @normal_tag = create(:tag, name: "random", category: Tag.categories.general, post_count: 1000)
+          @normal_user = create(:user)
+          @admin = create(:admin_user)
+        end
+
+        should "not remove deprecated status if the user is not an admin" do
+          put_auth tag_path(@deprecated_tag), @normal_user, params: {tag: { is_deprecated: false }}
+
+          assert_response 403
+          assert(true, @deprecated_tag.reload.is_deprecated?)
+        end
+
+        should "remove the deprecated status if the user is admin" do
+          put_auth tag_path(@deprecated_tag), @admin, params: {tag: { is_deprecated: false }}
+
+          assert_redirected_to @deprecated_tag
+          assert(false, @deprecated_tag.reload.is_deprecated?)
+        end
+
+        should "allow marking a tag as deprecated if it's empty" do
+          put_auth tag_path(@nondeprecated_tag), @normal_user, params: {tag: { is_deprecated: true }}
+
+          assert_redirected_to @nondeprecated_tag
+          assert(true, @nondeprecated_tag.reload.is_deprecated?)
+        end
+
+        should "not allow marking a tag as deprecated if it's not empty" do
+          put_auth tag_path(@normal_tag), @normal_user, params: {tag: { is_deprecated: true }}
+
+          assert_response 403
+          assert(false, @normal_tag.reload.is_deprecated?)
+        end
+
+        should "allow admins to mark tags as deprecated" do
+          put_auth tag_path(@normal_tag), @admin, params: {tag: { is_deprecated: true }}
+
+          assert_redirected_to @normal_tag
+          assert(true, @normal_tag.reload.is_deprecated?)
+        end
+      end
+
       should "not change category when the tag is too large to be changed by a builder" do
         @tag.update(category: Tag.categories.general, post_count: 1001)
         put_auth tag_path(@tag), @user, params: {:tag => {:category => Tag.categories.artist}}
diff --git a/test/unit/bulk_update_request_test.rb b/test/unit/bulk_update_request_test.rb
index c498fcbda..3ebe44776 100644
--- a/test/unit/bulk_update_request_test.rb
+++ b/test/unit/bulk_update_request_test.rb
@@ -446,6 +446,34 @@ class BulkUpdateRequestTest < ActiveSupport::TestCase
         end
       end
 
+      context "the deprecate command" do
+        should "deprecate the tag" do
+          @tag = create(:tag, name: "silver_hair")
+          @bur = create_bur!("deprecate silver_hair", @admin)
+
+          assert_equal(true, @tag.reload.is_deprecated?)
+        end
+
+        should "remove implications" do
+          @ti1 = create(:tag_implication, antecedent_name: "silver_hair", consequent_name: "old_woman")
+          @ti2 = create(:tag_implication, antecedent_name: "my_literal_dog", consequent_name: "silver_hair")
+          @bur = create_bur!("deprecate silver_hair", @admin)
+
+          assert_equal("deleted", @ti1.reload.status)
+          assert_equal("deleted", @ti2.reload.status)
+          assert_equal("approved", @bur.reload.status)
+        end
+      end
+
+      context "the undeprecate command" do
+        should "undeprecate the tag" do
+          @tag = create(:tag, name: "silver_hair", is_deprecated: true)
+          @bur = create_bur!("undeprecate silver_hair", @admin)
+
+          assert_equal(false, @tag.reload.is_deprecated?)
+        end
+      end
+
       context "that contains a mass update followed by an alias" do
         should "make the alias take effect after the mass update" do
           @p1 = create(:post, tag_string: "maid_dress")
diff --git a/test/unit/post_test.rb b/test/unit/post_test.rb
index b678a048f..b910ad631 100644
--- a/test/unit/post_test.rb
+++ b/test/unit/post_test.rb
@@ -479,6 +479,23 @@ class PostTest < ActiveSupport::TestCase
         end
       end
 
+      context "tagged with a deprecated tag" do
+        should "not remove the tag if the tag was already in the post" do
+          bad_tag = create(:tag, name: "bad_tag")
+          old_post = FactoryBot.create(:post, tag_string: "bad_tag")
+          bad_tag.update!(is_deprecated: true)
+          old_post.update!(tag_string: "asd bad_tag")
+          assert_equal("asd bad_tag", old_post.reload.tag_string)
+
+        end
+
+        should "not add the tag if it is being added" do
+          create(:tag, name: "a_bad_tag", is_deprecated: true)
+          @post.update!(tag_string: "asd a_bad_tag")
+          assert_equal("asd", @post.reload.tag_string)
+        end
+      end
+
       context "tagged with a metatag" do
         context "for typing a tag" do
           setup do