diff --git a/lib/rucio/core/importer.py b/lib/rucio/core/importer.py
index ced3ed7a66..53c772b448 100644
--- a/lib/rucio/core/importer.py
+++ b/lib/rucio/core/importer.py
@@ -13,7 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import TYPE_CHECKING
+from collections.abc import Iterable
+from typing import TYPE_CHECKING, Any
 
 from rucio.common.config import config_get
 from rucio.common.exception import RSEOperationNotSupported
@@ -28,7 +29,7 @@
 
 
 @transactional_session
-def import_rses(rses, rse_sync_method='edit', attr_sync_method='edit', protocol_sync_method='edit', vo='def', *, session: "Session"):
+def import_rses(rses: dict[str, dict[str, Any]], rse_sync_method: str = 'edit', attr_sync_method: str = 'edit', protocol_sync_method: str = 'edit', vo: str = 'def', *, session: "Session") -> None:
     new_rses = []
     for rse_name in rses:
         rse = rses[rse_name]
@@ -136,7 +137,7 @@ def import_rses(rses, rse_sync_method='edit', attr_sync_method='edit', protocol_
 
 
 @transactional_session
-def import_distances(distances, vo='def', *, session: "Session"):
+def import_distances(distances, vo: str = 'def', *, session: "Session") -> None:
     for src_rse_name in distances:
         src = rse_module.get_rse_id(rse=src_rse_name, vo=vo, session=session)
         for dest_rse_name in distances[src_rse_name]:
@@ -156,7 +157,7 @@ def import_distances(distances, vo='def', *, session: "Session"):
 
 
 @transactional_session
-def import_identities(identities, account_name, old_identities, old_identity_account, account_email, *, session: "Session"):
+def import_identities(identities: Iterable[dict[str, Any]], account_name: str, old_identities: Iterable[tuple], old_identity_account: tuple[str, str, str], account_email: str, *, session: "Session") -> None:
     for identity in identities:
         identity['type'] = IdentityType[identity['type'].upper()]
 
@@ -185,7 +186,7 @@ def import_identities(identities, account_name, old_identities, old_identity_acc
 
 
 @transactional_session
-def import_accounts(accounts, vo='def', *, session: "Session"):
+def import_accounts(accounts: Iterable[dict[str, Any]], vo: str = 'def', *, session: "Session") -> None:
     vo_filter = {'account': InternalAccount(account='*', vo=vo)}
     old_accounts = {account['account']: account for account in account_module.list_accounts(filter_=vo_filter, session=session)}
     missing_accounts = [account for account in accounts if account['account'] not in old_accounts]
@@ -222,7 +223,7 @@ def import_accounts(accounts, vo='def', *, session: "Session"):
 
 
 @transactional_session
-def import_data(data, vo='def', *, session: "Session"):
+def import_data(data: dict[str, Any], vo: str = 'def', *, session: "Session") -> None:
     """
     Import data to add and update records in Rucio.