diff --git a/api/utils/serializer/v1/compensation.py b/api/utils/serializer/v1/compensation.py
index a94527a5..9b33e65e 100644
--- a/api/utils/serializer/v1/compensation.py
+++ b/api/utils/serializer/v1/compensation.py
@@ -88,6 +88,11 @@ class CompensationAPISerializerV1(AbstractModelAPISerializerV1, AbstractCompensa
             # Nothing to do here
             return obj
 
+        # Transform a potential external identifier into an internal one
+        intervention_ext_id = self._get_external_identifier(intervention_id)
+        if intervention_ext_id:
+            intervention_id = intervention_ext_id.internal_id
+
         intervention = Intervention.objects.get(
             id=intervention_id,
         )
diff --git a/api/utils/serializer/v1/deduction.py b/api/utils/serializer/v1/deduction.py
index 708b3775..5d28c31b 100644
--- a/api/utils/serializer/v1/deduction.py
+++ b/api/utils/serializer/v1/deduction.py
@@ -62,6 +62,14 @@ class DeductionAPISerializerV1(AbstractModelAPISerializerV1,
         if surface <= 0:
             raise ValueError("Surface must be > 0 m²")
 
+        # Check if external identifiers need to be mapped onto internal ones
+        acc_ext_id = self._get_external_identifier(acc_id)
+        intervention_ext_id = self._get_external_identifier(intervention_id)
+        if acc_ext_id:
+            acc_id = acc_ext_id.internal_id
+        if intervention_ext_id:
+            intervention_id = intervention_ext_id.internal_id
+
         acc = EcoAccount.objects.get(
             id=acc_id,
             deleted__isnull=True,