Index: Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs
===================================================================
diff -u -rae137e9d1b26f1b37e47f2b4a6bf9ae03c6c9b2e -rccad0677b59f5f6e5303e9ebfdb5ee3670f35610
--- Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs	(.../CalculationConfigurationWriter.cs)	(revision ae137e9d1b26f1b37e47f2b4a6bf9ae03c6c9b2e)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs	(.../CalculationConfigurationWriter.cs)	(revision ccad0677b59f5f6e5303e9ebfdb5ee3670f35610)
@@ -154,7 +154,10 @@
                     WriteCalculation(calculation, writer);
                 }
 
-                throw new ArgumentException($"Cannot write calculation of type '{child.GetType()}' using this writer.");
+                if (innerGroup == null && calculation == null)
+                {
+                    throw new ArgumentException($"Cannot write calculation of type '{child.GetType()}' using this writer.");
+                }
             }
         }