diff --git a/cla_backend/apps/call_centre/serializers.py b/cla_backend/apps/call_centre/serializers.py
index 2d9518864..8854d0c5d 100644
--- a/cla_backend/apps/call_centre/serializers.py
+++ b/cla_backend/apps/call_centre/serializers.py
@@ -196,6 +196,21 @@ class Meta(EODDetailsSerializerBase.Meta):
 
 
 class EligibilityCheckSerializer(EligibilityCheckSerializerBase):
+    def validate_property_set(self, value):
+        property_item = super(EligibilityCheckSerializer, self).validate_property_set(value)
+        # Iterate through each item (property) in the property_set list
+        for property_item in value:
+            if property_item.get('value') is None:
+                raise serializers.ValidationError("Property 'value' cannot be null.")
+            if property_item.get('mortgage_left') is None:
+                raise serializers.ValidationError("Property 'mortgage_left' cannot be null.")
+            if property_item.get('share') is None:
+                raise serializers.ValidationError("Property 'share' cannot be null.")
+            if property_item.get('disputed') is None:
+                raise serializers.ValidationError("Property 'disputed' cannot be null.")
+            if property_item.get('main') is None:
+                raise serializers.ValidationError("Property 'main' cannot be null.")
+        return value
     property_set = PropertySerializer(many=True, required=False)
     you = PersonSerializer(required=False, allow_null=True)
     partner = PartnerPersonSerializer(required=False, allow_null=True)
diff --git a/cla_backend/apps/legalaid/tests/views/mixins/eligibility_check_api.py b/cla_backend/apps/legalaid/tests/views/mixins/eligibility_check_api.py
index c933f9155..dadc33723 100644
--- a/cla_backend/apps/legalaid/tests/views/mixins/eligibility_check_api.py
+++ b/cla_backend/apps/legalaid/tests/views/mixins/eligibility_check_api.py
@@ -742,7 +742,7 @@ def test_patch_properties(self):
         """
         PATCH should add/remove/change properties.
         """
-        properties = make_recipe("legalaid.property", eligibility_check=self.resource, _quantity=4, disputed=False)
+        properties = make_recipe("legalaid.property", eligibility_check=self.resource, _quantity=4, disputed=False, main=False)
 
         # making extra properties not associated to this eligibility check
         make_recipe("legalaid.property", _quantity=5)
@@ -753,8 +753,8 @@ def test_patch_properties(self):
         # an extra one
         data = {
             "property_set": [
-                {"value": 111, "mortgage_left": 222, "share": 33, "id": properties[0].id, "disputed": True},
-                {"value": 999, "mortgage_left": 888, "share": 77, "disputed": True},
+                {"value": 111, "mortgage_left": 222, "share": 33, "id": properties[0].id, "disputed": True, "main": False},
+                {"value": 999, "mortgage_left": 888, "share": 77, "disputed": True, "main": False},
             ]
         }
         response = self.client.patch(
@@ -1114,7 +1114,7 @@ def test_others_property_cannot_be_set(self):
         """
         other_property = make_recipe("legalaid.property")
         data = {
-            "property_set": [{"value": 0, "mortgage_left": 0, "share": 0, "id": other_property.pk, "disputed": False}]
+            "property_set": [{"value": 0, "mortgage_left": 0, "share": 0, "id": other_property.pk, "disputed": False, "main": False}]
         }
         response = self.client.patch(
             self.detail_url, data, format="json", HTTP_AUTHORIZATION=self.get_http_authorization()