diff --git a/src/schemas/users.py b/src/schemas/users.py
index 02f8f1c..06bd51e 100644
--- a/src/schemas/users.py
+++ b/src/schemas/users.py
@@ -3,7 +3,7 @@ from typing import Annotated
 from pydantic import BaseModel, BeforeValidator, ConfigDict, EmailStr
 
 from src.schemas.tasks import TaskWithId
-from src.schemas.validators import ensure_password
+from src.schemas.validators import ensure_password, ensure_username
 
 
 class UserUpdate(BaseModel):
@@ -38,7 +38,7 @@ class UserRequest(BaseModel):
 
 
 class UserRequestADD(BaseModel):
-    username: str
+    username: Annotated[str, BeforeValidator(ensure_username)]
     email: EmailStr | None = None
     password: Annotated[str, BeforeValidator(ensure_password)]
 
diff --git a/src/schemas/validators.py b/src/schemas/validators.py
index 5910daf..32db8f6 100644
--- a/src/schemas/validators.py
+++ b/src/schemas/validators.py
@@ -1,11 +1,21 @@
 from typing import Any
 
 
-def ensure_password(value: Any) -> Any:
+def ensure_password(value: Any) -> str:
     if not isinstance(value, str):
         raise TypeError("Password must be a string")
+    value = value.strip()
     if len(value) < 8:
         raise ValueError("Password must be at least 8 characters")
-    if value.strip() == "":
+    elif value.strip() == "":
         raise ValueError("Password cannot be empty")
     return value
+
+
+def ensure_username(value: str) -> str:
+    value = value.strip()
+    if len(value) < 3:
+        raise ValueError("Username must be at least 3 characters")
+    elif value.lower() in ['admin', 'moderator', 'админ', 'модератор']:
+        raise ValueError("Login is already taken")
+    return value
\ No newline at end of file