diff --git a/app/include_topbar.php b/app/include_topbar.php
index 9999cd6..a031eac 100644
--- a/app/include_topbar.php
+++ b/app/include_topbar.php
@@ -420,7 +420,9 @@ function do_switch_branch(company_id) {
     autoPrepare: true,
     checkRequired: 0,
     action: 'update',
-    company_id: company_id,
+    // Sent under its own key: prepare_form_data() always fills company_id with
+    // the CURRENT company, and only options.data reaches the payload.
+    data: { target_company_id: company_id },
     onSuccess: function(res) {
       window.location.reload();
     }
diff --git a/app/setting/api/engine/switch_branch.php b/app/setting/api/engine/switch_branch.php
index 4f84cb9..47a3eb7 100644
--- a/app/setting/api/engine/switch_branch.php
+++ b/app/setting/api/engine/switch_branch.php
@@ -3,7 +3,11 @@
  * switch_branch.php — Switch the active company for the current session.
  *
  * action: 'read'   → return list of companies the user belongs to
- * action: 'update' → switch to the requested company_id
+ * action: 'update' → switch to target_company_id
+ *
+ * The target is read from target_company_id, not company_id: every request
+ * carries company_id = the CURRENT company (prepare_form_data in custom.js),
+ * so reading it made a switch silently re-select the company already active.
  */
 session_start();
 require_once '../../../assets/utils/db_auth.php';
@@ -20,7 +24,7 @@ if ($action === 'read') {
 }
 
 if ($action === 'update') {
-    $target_company_id = (int)($data['company_id'] ?? 0);
+    $target_company_id = (int)($data['target_company_id'] ?? 0);
 
     if (!$target_company_id) {
         $answer['message'] = 'Invalid company.';