diff --git a/backend/README.md b/backend/README.md
index be2d8a1eb..bfb291f4e 100644
--- a/backend/README.md
+++ b/backend/README.md
@@ -45,4 +45,4 @@ run-command main --help
 
 * `download-legal` is an internal command to process privacy policy and terms of service files that will be served by the frontend.
 * `update-db` runs on docker container entry, and ensures the latest db migration has run, or if it's a new db then to kickstart that.
-* `create-invite-codes --n 50` is an internal command to create invite codes which can be used for registrations. The `--n` argument specifies the amount of codes generated, defaults to 50 if left empty.
+* `create-invite-codes n` is an internal command to create invite codes which can be used for user registrations. The `n` argument is an integer that specifies the amount of codes to be generated.
diff --git a/backend/src/appointment/commands/create_invite_codes.py b/backend/src/appointment/commands/create_invite_codes.py
index 7d8a7ab8a..34b4a7684 100644
--- a/backend/src/appointment/commands/create_invite_codes.py
+++ b/backend/src/appointment/commands/create_invite_codes.py
@@ -5,7 +5,7 @@
 from ..dependencies.database import get_engine_and_session
 
 
-def run(n: int = 50):
+def run(n: int):
     print(f"Generating {n} new invite codes...")
 
     codes = [str(uuid.uuid4()) for _ in range(n)]
diff --git a/backend/src/appointment/database/models.py b/backend/src/appointment/database/models.py
index 3ab281ec0..49db1b255 100644
--- a/backend/src/appointment/database/models.py
+++ b/backend/src/appointment/database/models.py
@@ -284,3 +284,8 @@ class Invite(Base):
     status = Column(Enum(InviteStatus), index=True)
 
     subscriber = relationship("Subscriber", back_populates="invite")
+
+    @property
+    def is_used(self) -> bool:
+        """True if the invite code is assigned to a subscriber"""
+        return self.subscriber_id is not None
diff --git a/backend/src/appointment/database/repo.py b/backend/src/appointment/database/repo.py
index 086572287..94c49233f 100644
--- a/backend/src/appointment/database/repo.py
+++ b/backend/src/appointment/database/repo.py
@@ -564,7 +564,7 @@ def schedule_has_slot(db: Session, schedule_id: int, slot_id: int):
 def use_invite_code(db: Session, code: str, subscriber_id: int):
     """set existing invite code status to revoked"""
     db_invite = db.query(models.Invite).filter(models.Invite.code == code).first()
-    if db_invite.status == models.InviteStatus.active:
+    if db_invite.status == models.InviteStatus.active and not db_invite.is_used:
         db_invite.subscriber_id = subscriber_id
         db.commit()
         db.refresh(db_invite)
diff --git a/backend/src/appointment/routes/commands.py b/backend/src/appointment/routes/commands.py
index 4e168f3fb..2c87e4585 100644
--- a/backend/src/appointment/routes/commands.py
+++ b/backend/src/appointment/routes/commands.py
@@ -36,5 +36,5 @@ def download_legal_docs():
 
 
 @router.command('create-invite-codes')
-def create_app_invite_codes(n: int = 50):
+def create_app_invite_codes(n: int):
     create_invite_codes.run(n)