diff --git a/swh/auth/django/utils.py b/swh/auth/django/utils.py
--- a/swh/auth/django/utils.py
+++ b/swh/auth/django/utils.py
@@ -80,8 +80,7 @@
     user = oidc_user_from_decoded_token(decoded_token, client_id=oidc_client.client_id)
 
     # get authentication init datetime
-    auth_time = decoded_token.get("auth_time", decoded_token["iat"])
-    auth_datetime = datetime.fromtimestamp(auth_time)
+    auth_datetime = datetime.fromtimestamp(decoded_token["iat"])
     exp_datetime = datetime.fromtimestamp(decoded_token["exp"])
 
     # compute OIDC tokens expiration date
diff --git a/swh/auth/pytest_plugin.py b/swh/auth/pytest_plugin.py
--- a/swh/auth/pytest_plugin.py
+++ b/swh/auth/pytest_plugin.py
@@ -102,17 +102,13 @@
         if userinfo is not None:
             decoded = {**decoded, **userinfo}
         # tweak auth and exp time for tests
-        auth_time = decoded.get("auth_time", decoded["iat"])
-        expire_in = decoded["exp"] - auth_time
+        expire_in = decoded["exp"] - decoded["iat"]
         if self.exp is not None:
             decoded["exp"] = self.exp
-            auth_time = self.exp - expire_in
-            decoded["iat"] = auth_time
-            decoded["auth_time"] = auth_time
+            decoded["iat"] = self.exp - expire_in
         else:
             now = int(datetime.now(tz=timezone.utc).timestamp())
             decoded["iat"] = now
-            decoded["auth_time"] = now
             decoded["exp"] = now + expire_in
         decoded["groups"] = self.user_groups
         decoded["aud"] = [self.client_id, "account"]