diff --git a/Library/Homebrew/cask/installer.rb b/Library/Homebrew/cask/installer.rb
index 0e2e89396c..9b00efab5e 100644
--- a/Library/Homebrew/cask/installer.rb
+++ b/Library/Homebrew/cask/installer.rb
@@ -574,7 +574,7 @@ on_request: true)
 
     sig { void }
     def forbidden_tap_check
-      return if Homebrew::EnvConfig.forbidden_taps.blank? && Homebrew::EnvConfig.allowed_taps.blank?
+      return if Tap.allowed_taps.blank? && Tap.forbidden_taps.blank?
 
       owner = Homebrew::EnvConfig.forbidden_owner
       owner_contact = if (contact = Homebrew::EnvConfig.forbidden_owner_contact.presence)
@@ -587,24 +587,28 @@ on_request: true)
           next if dep_tap.blank? || dep_tap.allowed_by_env?
 
           dep_full_name = cask_or_formula.full_name
-          raise CaskCannotBeInstalledError.new(@cask, <<~EOS
-            The installation of #{@cask} has a dependency #{dep_full_name}
-            but #{owner} has either not allowed the #{dep_tap} in `HOMEBREW_ALLOWED_TAPS` or
-            has forbidden the #{dep_tap} in `HOMEBREW_FORBIDDEN_TAPS`.#{owner_contact}
-          EOS
-          )
+          error_message = +"The installation of #{@cask} has a dependency #{dep_full_name}\n" \
+                           "from the #{dep_tap} tap but #{owner} "
+          error_message << "has not allowed this tap in `HOMEBREW_ALLOWED_TAPS`" unless dep_tap.allowed_by_env?
+          error_message << " and\n" if !dep_tap.allowed_by_env? && dep_tap.forbidden_by_env?
+          error_message << "has forbidden this tap in `HOMEBREW_FORBIDDEN_TAPS`" if dep_tap.forbidden_by_env?
+          error_message << ".#{owner_contact}"
+
+          raise CaskCannotBeInstalledError.new(@cask, error_message)
         end
       end
 
       cask_tap = @cask.tap
       return if cask_tap.blank? || cask_tap.allowed_by_env?
 
-      raise CaskCannotBeInstalledError.new(@cask, <<~EOS
-        The installation of #{@cask.full_name} has the tap #{cask_tap}
-        which is either not allowed by #{owner} in `HOMEBREW_ALLOWED_TAPS` or
-        is forbidden by #{owner} in `HOMEBREW_FORBIDDEN_TAPS`.#{owner_contact}
-      EOS
-      )
+      error_message = +"The installation of #{@cask.full_name} has the tap #{cask_tap}\n" \
+                       "but #{owner} "
+      error_message << "has not allowed this tap in `HOMEBREW_ALLOWED_TAPS`" unless cask_tap.allowed_by_env?
+      error_message << " and\n" if !cask_tap.allowed_by_env? && cask_tap.forbidden_by_env?
+      error_message << "has forbidden this tap in `HOMEBREW_FORBIDDEN_TAPS`" if cask_tap.forbidden_by_env?
+      error_message << ".#{owner_contact}"
+
+      raise CaskCannotBeInstalledError.new(@cask, error_message)
     end
 
     sig { void }
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index f9734eb262..b417b5d941 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -1381,7 +1381,7 @@ on_request: installed_on_request?, options:)
 
   sig { void }
   def forbidden_tap_check
-    return if Homebrew::EnvConfig.forbidden_taps.blank? && Homebrew::EnvConfig.allowed_taps.blank?
+    return if Tap.allowed_taps.blank? && Tap.forbidden_taps.blank?
 
     owner = Homebrew::EnvConfig.forbidden_owner
     owner_contact = if (contact = Homebrew::EnvConfig.forbidden_owner_contact.presence)
@@ -1391,26 +1391,32 @@ on_request: installed_on_request?, options:)
     unless ignore_deps?
       compute_dependencies.each do |(dep, _options)|
         dep_tap = dep.tap
-        next if dep_tap.blank? || dep_tap.allowed_by_env?
+        next if dep_tap.blank? || (dep_tap.allowed_by_env? && !dep_tap.forbidden_by_env?)
 
-        raise CannotInstallFormulaError, <<~EOS
-          The installation of #{formula.name} has a dependency #{dep.name}
-          but #{owner} has either not allowed the #{dep_tap} tap in `HOMEBREW_ALLOWED_TAPS` or
-          has forbidden the #{dep_tap} tap in `HOMEBREW_FORBIDDEN_TAPS`.#{owner_contact}
-        EOS
+        error_message = +"The installation of #{formula.name} has a dependency #{dep.name}\n" \
+                         "from the #{dep_tap} tap but #{owner} "
+        error_message << "has not allowed this tap in `HOMEBREW_ALLOWED_TAPS`" unless dep_tap.allowed_by_env?
+        error_message << " and\n" if !dep_tap.allowed_by_env? && dep_tap.forbidden_by_env?
+        error_message << "has forbidden this tap in `HOMEBREW_FORBIDDEN_TAPS`" if dep_tap.forbidden_by_env?
+        error_message << ".#{owner_contact}"
+
+        raise CannotInstallFormulaError, error_message
       end
     end
 
     return if only_deps?
 
     formula_tap = formula.tap
-    return if formula_tap.blank? || formula_tap.allowed_by_env?
+    return if formula_tap.blank? || (formula_tap.allowed_by_env? && !formula_tap.forbidden_by_env?)
 
-    raise CannotInstallFormulaError, <<~EOS
-      The installation of #{formula.full_name} has the tap #{formula_tap}
-      which is either not allowed by #{owner} in `HOMEBREW_ALLOWED_TAPS` or
-      is forbidden by #{owner} in `HOMEBREW_FORBIDDEN_TAPS`.#{owner_contact}
-    EOS
+    error_message = +"The installation of #{formula.full_name} has the tap #{formula_tap}\n" \
+                     "but #{owner} "
+    error_message << "has not allowed this tap in `HOMEBREW_ALLOWED_TAPS`" unless formula_tap.allowed_by_env?
+    error_message << " and\n" if !formula_tap.allowed_by_env? && formula_tap.forbidden_by_env?
+    error_message << "has forbidden this tap in `HOMEBREW_FORBIDDEN_TAPS`" if formula_tap.forbidden_by_env?
+    error_message << ".#{owner_contact}"
+
+    raise CannotInstallFormulaError, error_message
   end
 
   sig { void }
diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index 527fc0e156..b386eaa985 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -1095,12 +1095,16 @@ class Tap
   def allowed_by_env?
     @allowed_by_env ||= begin
       allowed_taps = self.class.allowed_taps
-      forbidden_taps = self.class.forbidden_taps
 
-      (official? || allowed_taps.blank? || allowed_taps.include?(self)) && forbidden_taps.exclude?(self)
+      official? || allowed_taps.blank? || allowed_taps.include?(self)
     end
   end
 
+  sig { returns(T::Boolean) }
+  def forbidden_by_env?
+    @forbidden_by_env ||= self.class.forbidden_taps.include?(self)
+  end
+
   private
 
   sig { params(file: Pathname).returns(T.any(T::Array[String], Hash)) }