diff --git a/app/Plan/UseCases/CreatePlan.php b/app/Plan/UseCases/CreatePlan.php
index 9841b33..c732b28 100644
--- a/app/Plan/UseCases/CreatePlan.php
+++ b/app/Plan/UseCases/CreatePlan.php
@@ -30,33 +30,10 @@ class CreatePlan
      */
     public function execute(CreatePlanRequest $request): Plan
     {
-        if ($request->userId === null) {
-            throw new BadRequestException('userId is required');
-        }
-
-        if ($request->textId === null) {
-            throw new BadRequestException('textId is required');
-        }
-
-        if ($request->name === null) {
-            throw new BadRequestException('name is required');
-        }
-
-        if ($request->dateStart === null) {
-            throw new BadRequestException('date start is required');
-        }
-
-        if ($request->dateEnd === null) {
-            throw new BadRequestException('date end is required');
-        }
-
+        $this->validate($request);
         $startDate = new DateTimeImmutable($request->dateStart);
         $endDate = new DateTimeImmutable($request->dateEnd);
 
-        if ($endDate < $startDate) {
-            throw new BadRequestException('date end cannot be before date start');
-        }
-
         $userId = $request->userId;
         $user = $this->userRepo->find($userId);
         if ($user === null) {
@@ -115,4 +92,34 @@ class CreatePlan
         }
         return array_values($result);
     }
+
+    private function validate(CreatePlanRequest $request): void
+    {
+        if ($request->userId === null) {
+            throw new BadRequestException('userId is required');
+        }
+
+        if ($request->textId === null) {
+            throw new BadRequestException('textId is required');
+        }
+
+        if ($request->name === null) {
+            throw new BadRequestException('name is required');
+        }
+
+        if ($request->dateStart === null) {
+            throw new BadRequestException('date start is required');
+        }
+
+        if ($request->dateEnd === null) {
+            throw new BadRequestException('date end is required');
+        }
+
+        $startDate = new DateTimeImmutable($request->dateStart);
+        $endDate = new DateTimeImmutable($request->dateEnd);
+
+        if ($endDate < $startDate) {
+            throw new BadRequestException('date end cannot be before date start');
+        }
+    }
 }