diff --git a/backend/app/schemas/auth.py b/backend/app/schemas/auth.py
new file mode 100644
index 0000000..c40384b
--- /dev/null
+++ b/backend/app/schemas/auth.py
@@ -0,0 +1,17 @@
+"""Authentication schemas."""
+from pydantic import BaseModel, EmailStr, Field
+
+
+class LoginRequest(BaseModel):
+    email: EmailStr
+    password: str
+
+
+class RegisterRequest(BaseModel):
+    email: EmailStr
+    username: str = Field(..., min_length=2, max_length=100)
+    password: str = Field(..., min_length=6)
+    role: str = "worker"
+    tenant_slug: str = "default"  # for first user in a new tenant
+    tenant_name: str = ""  # if creating a new tenant
+    invite_code: str = ""  # for joining existing tenant (MVP: not enforced)