diff --git a/src/server/BreCal/validators/input_validation_shipcall.py b/src/server/BreCal/validators/input_validation_shipcall.py
index 729a896..59b8b35 100644
--- a/src/server/BreCal/validators/input_validation_shipcall.py
+++ b/src/server/BreCal/validators/input_validation_shipcall.py
@@ -123,6 +123,9 @@ class InputValidationShipcall():
         # time values must use future-dates
         InputValidationShipcall.check_times_are_in_future(loadedModel, content)
 
+        # the type of a shipcall may not be changed. It can only be set with the initial POST-request.
+        InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+
         # some arguments must not be provided
         InputValidationShipcall.check_forbidden_arguments(content, forbidden_keys=forbidden_keys)
         return
@@ -247,6 +250,16 @@ class InputValidationShipcall():
         if not valid_participant_types: # #TODO: according to Daniel, there may eventually be multi-assignment of participants for the same role
             raise ValidationError(f"every participant id and type should be listed only once. Found multiple entries for one of the participants.")
         
+    @staticmethod
+    def check_shipcall_type_is_unchanged(loadedModel:dict):
+        # the type of a shipcall may only be set on POST requests. Afterwards, shipcall types may not be changed.
+        query = SQLQuery.get_shipcall_by_id()
+        shipcall = execute_sql_query_standalone(query=query, model=Shipcall, param={"id":loadedModel.get("id")}, command_type="single")
+
+        if int(loadedModel["type"]) != int(shipcall.type):
+            raise ValidationError(f"The shipcall type may only be set in the initial POST-request. Afterwards, changing the shipcall type is not allowed.") # @pytest.raises
+        return
+        
     @staticmethod
     def check_forbidden_arguments(content:dict, forbidden_keys=["evaluation", "evaluation_message"]):
         """
diff --git a/src/server/tests/validators/test_input_validation_shipcall.py b/src/server/tests/validators/test_input_validation_shipcall.py
index df41f1f..87b3b7f 100644
--- a/src/server/tests/validators/test_input_validation_shipcall.py
+++ b/src/server/tests/validators/test_input_validation_shipcall.py
@@ -901,3 +901,35 @@ def test_post_data_with_valid_data(get_stub_token):
     assert response.status_code==201
     return
 
+def test_input_validation_shipcall_put_fails_when_type_differs():
+    from marshmallow import ValidationError
+    from BreCal.stubs.shipcall import get_stub_valid_shipcall_arrival
+    from BreCal.schemas import model
+    from BreCal.database.sql_queries import SQLQuery
+    from BreCal.database.sql_handler import execute_sql_query_standalone
+
+    from BreCal.validators.input_validation_shipcall import InputValidationShipcall
+
+    # stub data
+    put_data = get_stub_valid_shipcall_arrival()
+    put_data["id"] = 3
+    loadedModel = model.ShipcallSchema().load(data=put_data, many=False, partial=True)
+
+    # load data from DB
+    shipcall_id = loadedModel.get("id")
+    query = SQLQuery.get_shipcall_by_id()
+    shipcall = execute_sql_query_standalone(query=query, model=model.Shipcall, param={"id":shipcall_id}, command_type="single")
+
+    # create failure case. Ensures that the type is not the same as in the loaded shipcall from the DB
+    failure_case = 1 if shipcall.type==2 else 2
+    loadedModel["type"] = model.ShipcallType(failure_case)
+
+    # should fail: different 'type'
+    with pytest.raises(ValidationError, match="The shipcall type may only be set in the initial POST-request. Afterwards, changing the shipcall type is not allowed"):
+        InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+
+    # should pass: same 'type'
+    loadedModel["type"] = shipcall.type
+    InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+    return
+