diff --git a/src/Controller/UserController.php b/src/Controller/UserController.php
index e86d7c2..819c664 100644
--- a/src/Controller/UserController.php
+++ b/src/Controller/UserController.php
@@ -872,6 +872,9 @@ class UserController extends AbstractController
                 $email = $user->getEmail();
                 $existingUser = $this->userRepository->findOneBy(['email' => $email]);
 
+                if($this->userService->checkUserOrganizationLinkExists($existingUser, $org)){
+                    return $this->json(['error' => "L'utilisateur existe déjà dans votre organisation"], 400);
+                }
                 // CASE A: User exists -> Add to org
                 if ($existingUser) {
                     // Check if already in org to avoid logic errors or duplicate logs
diff --git a/src/Service/OrganizationsService.php b/src/Service/OrganizationsService.php
index 888ac83..f92e87c 100644
--- a/src/Service/OrganizationsService.php
+++ b/src/Service/OrganizationsService.php
@@ -142,18 +142,12 @@ class OrganizationsService
 
         $roleAdmin = $this->entityManager->getRepository(Roles::class)->findOneBy(['name' => 'ADMIN']);
 
-        $adminUOs = $this->uoRepository->findBy(['organization' => $data['organization'], 'isActive' => true]);
+        $adminUOs = $this->uoRepository->findBy(['organization' => $data['organization'], 'isActive' => true, 'role' => $roleAdmin]);
 
         foreach ($adminUOs as $adminUO) {
-            $uoa = $this->entityManager->getRepository(UsersOrganizations::class)
-                ->findOneBy([
-                    'userOrganization' => $adminUO,
-                    'role' => $roleAdmin,
-                    'isActive' => true
-                ]);
             switch ($type) {
                 case 'USER_ACCEPTED':
-                    if ($uoa && $adminUO->getUsers()->getId() !== $data['user']->getId() ) {
+                    if ($adminUO->getUsers()->getId() !== $data['user']->getId() ) {
                         $newUser = $data['user'];
                         $this->notificationService->notifyUserAcceptedInvite(
                             $adminUO->getUsers(),
@@ -167,7 +161,7 @@ class OrganizationsService
                     }
                     break;
                 case 'USER_INVITED':
-                    if ($uoa) {
+                    if ($adminUO->getUsers()->getId() !== $data['user']->getId() ) {
                         $invitedUser = $data['user'];
                         $this->notificationService->notifyUserInvited(
                             $adminUO->getUsers(),
@@ -182,7 +176,7 @@ class OrganizationsService
 
                     break;
                 case 'USER_DEACTIVATED':
-                    if ($uoa && $adminUO->getUsers()->getId() !== $data['user']->getId() ) {
+                    if ($adminUO->getUsers()->getId() !== $data['user']->getId() ) {
                         $removedUser = $data['user'];
                         $this->notificationService->notifyUserDeactivated(
                             $adminUO->getUsers(),
@@ -197,7 +191,7 @@ class OrganizationsService
 
                     break;
                 case 'USER_DELETED':
-                    if ($uoa && $adminUO->getUsers()->getId() !== $data['user']->getId() ) {
+                    if ($adminUO->getUsers()->getId() !== $data['user']->getId() ) {
                         $removedUser = $data['user'];
                         $this->notificationService->notifyUserDeleted(
                             $adminUO->getUsers(),
@@ -211,7 +205,7 @@ class OrganizationsService
                     }
                     break;
                 case 'USER_ACTIVATED':
-                    if ($uoa && $adminUO->getUsers()->getId() !== $data['user']->getId() ) {
+                    if ($adminUO->getUsers()->getId() !== $data['user']->getId() ) {
                         $activatedUser = $data['user'];
                         $this->notificationService->notifyUserActivated(
                             $adminUO->getUsers(),
diff --git a/src/Service/UserService.php b/src/Service/UserService.php
index a40dc47..2c981e8 100644
--- a/src/Service/UserService.php
+++ b/src/Service/UserService.php
@@ -750,4 +750,21 @@ class UserService
         $this->entityManager->flush();
     }
 
+    /*
+     * Check if the user organization link doesn't already exist
+     * Return true if the link exists, false otherwise.
+     *
+     * @param User $user
+     * @param Organization $organization
+     * @return bool
+     * */
+    public function checkUserOrganizationLinkExists(User $user, Organizations $organization): bool
+    {
+        $existingLink = $this->entityManager->getRepository(UsersOrganizations::class)->findOneBy([
+            'users' => $user,
+            'organization' => $organization
+        ]);
+
+        return $existingLink !== null;
+    }
 }