diff --git a/src/server/BreCal/validators/input_validation_shipcall.py b/src/server/BreCal/validators/input_validation_shipcall.py
index aae7e11..5e498ff 100644
--- a/src/server/BreCal/validators/input_validation_shipcall.py
+++ b/src/server/BreCal/validators/input_validation_shipcall.py
@@ -90,7 +90,7 @@ class InputValidationShipcall():
         InputValidationShipcall.check_referenced_ids(loadedModel)
 
         # check for reasonable values in the shipcall fields and checks for forbidden keys. 
-        InputValidationShipcall.check_shipcall_values(loadedModel, content, forbidden_keys=["evaluation", "evaluation_message"])
+        InputValidationShipcall.check_shipcall_values(loadedModel, content, forbidden_keys=["evaluation", "evaluation_message"], is_put_data=True)
 
         # a canceled shipcall cannot be selected
         # Note: 'canceled' is allowed in PUT-requests, if it is not already set (which is checked by InputValidationShipcall.check_shipcall_is_cancel)
@@ -98,12 +98,15 @@ class InputValidationShipcall():
         return
     
     @staticmethod
-    def check_shipcall_values(loadedModel:dict, content:dict, forbidden_keys:list=["evaluation", "evaluation_message"]):
+    def check_shipcall_values(loadedModel:dict, content:dict, forbidden_keys:list=["evaluation", "evaluation_message"], is_put_data:bool=False):
         """
         individually checks each value provided in the loadedModel/content. 
         This function validates, whether the values are reasonable.
 
         Also, some data may not be set in a POST-request.
+
+        options:
+            is_put_data: bool. Some validation rules do not apply to POST data, but apply to PUT data. This flag separates the two. 
         """
         # Note: BreCal.schemas.model.ShipcallSchema has an internal validation, which the marshmallow library provides. This is used
         # to verify values individually, when the schema is loaded with data.
@@ -120,11 +123,12 @@ class InputValidationShipcall():
         if check_if_int_is_valid_flag(flags_value, enum_object=ParticipantFlag):
             raise ValidationError({"flags":f"incorrect value provided for 'flags'. Must be a valid combination of the flags."})
         
-        # 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)
+        if is_put_data:
+            # 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)
+        else:
+            # time values must use future-dates
+            InputValidationShipcall.check_times_are_in_future(loadedModel, content)
 
         # some arguments must not be provided
         InputValidationShipcall.check_forbidden_arguments(content, forbidden_keys=forbidden_keys)