Index: Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs
===================================================================
diff -u -r9743fa24b1c44e916c046064a361f4901f993f92 -r80453e2dd117acdee9dd3f57a4374516b828c1ea
--- Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs	(.../MacroStabilityInwardsGridSettingsProperties.cs)	(revision 9743fa24b1c44e916c046064a361f4901f993f92)
+++ Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs	(.../MacroStabilityInwardsGridSettingsProperties.cs)	(revision 80453e2dd117acdee9dd3f57a4374516b828c1ea)
@@ -183,6 +183,12 @@
         [DynamicReadOnlyValidationMethod]
         public bool DynamicReadOnlyValidationMethod(string propertyName)
         {
+            if (propertyName == nameof(TangentLineZTop) || propertyName == nameof(TangentLineZBottom))
+            {
+                return data.TangentLineDeterminationType == MacroStabilityInwardsTangentLineDeterminationType.LayerSeparated
+                       || AreGridSettingsReadOnly();
+            }
+
             return AreGridSettingsReadOnly();
         }