diff --git a/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py b/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
index a8c04d657f..5a832b7d29 100644
--- a/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
+++ b/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
@@ -75,9 +75,9 @@ class BindingConstraintProperties(BaseModel, extra=Extra.forbid, allow_populatio
     enabled: bool = True
     time_step: BindingConstraintFrequency = BindingConstraintFrequency.HOURLY
     operator: BindingConstraintOperator = BindingConstraintOperator.EQUAL
-    comments: str = ""
-    filter_year_by_year: str = ""
-    filter_synthesis: str = ""
+    comments: t.Optional[str] = None
+    filter_year_by_year: t.Optional[str] = None
+    filter_synthesis: t.Optional[str] = None
 
 
 class BindingConstraintProperties870(BindingConstraintProperties):
diff --git a/tests/variantstudy/test_command_factory.py b/tests/variantstudy/test_command_factory.py
index a0324a2722..09f45d30f3 100644
--- a/tests/variantstudy/test_command_factory.py
+++ b/tests/variantstudy/test_command_factory.py
@@ -132,6 +132,9 @@ def setup_class(self):
                     "operator": "equal",
                     "coeffs": {},
                     "values": "values",
+                    "comments": "",
+                    "filter_synthesis": "",
+                    "filter_year_by_year": "",
                 },
             ),
             CommandDTO(
@@ -144,7 +147,10 @@ def setup_class(self):
                         "operator": "equal",
                         "coeffs": {},
                         "values": "values",
-                    }
+                        "comments": "",
+                        "filter_synthesis": "",
+                        "filter_year_by_year": "",
+                    },
                 ],
             ),
             CommandDTO(
@@ -156,6 +162,9 @@ def setup_class(self):
                     "operator": "equal",
                     "coeffs": {},
                     "values": "values",
+                    "comments": "",
+                    "filter_synthesis": "",
+                    "filter_year_by_year": "",
                 },
             ),
             CommandDTO(
@@ -167,6 +176,9 @@ def setup_class(self):
                         "time_step": "hourly",
                         "operator": "equal",
                         "coeffs": {},
+                        "comments": "",
+                        "filter_synthesis": "",
+                        "filter_year_by_year": "",
                     }
                 ],
             ),