diff --git a/cshs.api.php b/cshs.api.php
new file mode 100644
index 0000000..fe055a7
--- /dev/null
+++ b/cshs.api.php
@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Hooks related to this module.
+ */
+
+// phpcs:disable DrupalPractice.CodeAnalysis.VariableAnalysis.UnusedVariable
+
+/**
+ * @addtogroup hooks
+ * @{
+ */
+
+/**
+ * Alter access to an option for `cshs` element.
+ *
+ * @param bool $hasAccess
+ *   Whether or not to give access.
+ * @param array $contexts
+ *   The array with the following keys:
+ *    - term: The taxonomy term option about which to check access.
+ *    - account: The user for whom the `cshs` element is being generated.
+ *    - field_name: The name of the field.
+ */
+function hook_cshs_term_access_alter(bool &$hasAccess, array $contexts): void {
+
+}
+
+/**
+ * Alter access to an option for `cshs` element for a particular field.
+ *
+ * @see hook_cshs_term_access_alter()
+ */
+function hook_cshs_FIELD_NAME_term_access_alter(bool &$hasAccess, array $contexts): void {
+
+}
+
+/**
+ * @} End of "addtogroup hooks".
+ */
diff --git a/src/CshsOptionsFromHelper.php b/src/CshsOptionsFromHelper.php
index a1a96ab..e78e18e 100644
--- a/src/CshsOptionsFromHelper.php
+++ b/src/CshsOptionsFromHelper.php
@@ -343,6 +343,16 @@ trait CshsOptionsFromHelper {
         $get_name = static fn (object $term): string => $term->name;
       }
 
+      // Contexts for alter hook.
+      $account = \Drupal::entityTypeManager()->getStorage('user')->load(\Drupal::currentUser()->id());
+      $field_name = (isset($this->fieldDefinition) && method_exists($this->fieldDefinition, 'getName')) ? $this->fieldDefinition?->getName() : NULL;
+      $hooks = [
+        'cshs_term_access',
+      ];
+      if ($field_name) {
+        $hooks[] = 'cshs_' . $field_name . '_term_access';
+      }
+
       foreach ($this->getVocabularies() as $vocabulary) {
         // Historically vocabulary labels are not translatable
         // and the `t()` trick should be applied.
@@ -356,8 +366,20 @@ trait CshsOptionsFromHelper {
           \assert(\is_numeric($term->tid));
           \assert(\is_string($term->name));
 
+          $hasAccess = TRUE;
+
+          $contexts = [
+            'term' => $term,
+            'account' => $account,
+            'field_name' => $field_name,
+          ];
+          // Allow other modules to override access.
+          // Creates hook_cshs_term_access_alter() and
+          // hook_cshs_FIELD_NAME_term_access_alter().
+          \Drupal::moduleHandler()->alter($hooks, $hasAccess, $contexts);
+
           // Allow only published terms, unless configured to allow all.
-          if ($allow_unpublished || (bool) $term->status) {
+          if (($allow_unpublished || (bool) $term->status) && $hasAccess) {
             // The `parents` always has a value. In case there are no parents
             // the value is `['0']`. Check for an empty value just in case.
             $parent_tid = ((string) \reset($term->parents)) ?: '0';