Index: Ringtoets/Common/src/Ringtoets.Common.Data/Hydraulics/HydraulicBoundaryLocationCalculation.cs
===================================================================
diff -u -rda7bb9a6d96d7118d6dcdc2ee17a11d5b43f44c7 -r0e2d1a46c627af6d19cdf21dff840716bac84045
--- Ringtoets/Common/src/Ringtoets.Common.Data/Hydraulics/HydraulicBoundaryLocationCalculation.cs	(.../HydraulicBoundaryLocationCalculation.cs)	(revision da7bb9a6d96d7118d6dcdc2ee17a11d5b43f44c7)
+++ Ringtoets/Common/src/Ringtoets.Common.Data/Hydraulics/HydraulicBoundaryLocationCalculation.cs	(.../HydraulicBoundaryLocationCalculation.cs)	(revision 0e2d1a46c627af6d19cdf21dff840716bac84045)
@@ -21,13 +21,14 @@
 
 using System;
 using Core.Common.Base;
+using Ringtoets.Common.Data.Calculation;
 
 namespace Ringtoets.Common.Data.Hydraulics
 {
     /// <summary>
     /// This class holds information about a calculation for a hydraulic boundary location.
     /// </summary>
-    public class HydraulicBoundaryLocationCalculation : Observable
+    public class HydraulicBoundaryLocationCalculation : Observable, ICalculatable
     {
         /// <summary>
         /// Creates a new instance of <see cref="HydraulicBoundaryLocationCalculation"/>.
@@ -71,17 +72,11 @@
             }
         }
 
-        /// <summary>
-        /// Gets a value indicating whether the calculation has already been calculated.
-        /// </summary>
-        /// <returns><c>true</c> if the calculation is fully calculated, <c>false</c> otherwise.</returns>
-        /// <remarks>A calculation is fully calculated, depending on whether the illustration points 
-        /// are set to be calculated.</remarks>
-        public bool IsCalculated
+        public bool ShouldCalculate
         {
             get
             {
-                return HasOutput && InputParameters.ShouldIllustrationPointsBeCalculated == Output.HasGeneralResult;
+                return !HasOutput || InputParameters.ShouldIllustrationPointsBeCalculated != Output.HasGeneralResult;
             }
         }
     }
Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Hydraulics/HydraulicBoundaryLocationCalculationTest.cs
===================================================================
diff -u -rda7bb9a6d96d7118d6dcdc2ee17a11d5b43f44c7 -r0e2d1a46c627af6d19cdf21dff840716bac84045
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Hydraulics/HydraulicBoundaryLocationCalculationTest.cs	(.../HydraulicBoundaryLocationCalculationTest.cs)	(revision da7bb9a6d96d7118d6dcdc2ee17a11d5b43f44c7)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Hydraulics/HydraulicBoundaryLocationCalculationTest.cs	(.../HydraulicBoundaryLocationCalculationTest.cs)	(revision 0e2d1a46c627af6d19cdf21dff840716bac84045)
@@ -23,6 +23,7 @@
 using System.Collections.Generic;
 using Core.Common.Base;
 using NUnit.Framework;
+using Ringtoets.Common.Data.Calculation;
 using Ringtoets.Common.Data.Hydraulics;
 using Ringtoets.Common.Data.TestUtil;
 using Ringtoets.Common.Data.TestUtil.IllustrationPoints;
@@ -53,6 +54,7 @@
             var calculation = new HydraulicBoundaryLocationCalculation(hydraulicBoundaryLocation);
 
             // Assert
+            Assert.IsInstanceOf<ICalculatable>(calculation);
             Assert.IsInstanceOf<Observable>(calculation);
             Assert.AreSame(hydraulicBoundaryLocation, calculation.HydraulicBoundaryLocation);
             Assert.IsNotNull(calculation.InputParameters);
@@ -78,48 +80,65 @@
         }
 
         [Test]
-        [TestCaseSource(nameof(GetHydraulicBoundaryLocationCalculations))]
-        public void IsCalculated_Always_ReturnIsCalculated(HydraulicBoundaryLocationCalculation hydraulicBoundaryLocationCalculation,
-                                                           bool expectedIsCalculated)
+        [TestCaseSource(nameof(GetCalculations))]
+        public void ShouldCalculate_Always_ReturnsExpectedValue(HydraulicBoundaryLocationCalculation calculation,
+                                                                bool expectedShouldCalculate)
         {
             // Call
-            bool isCalculated = hydraulicBoundaryLocationCalculation.IsCalculated;
+            bool shouldCalculate = calculation.ShouldCalculate;
 
             // Assert
-            Assert.AreEqual(expectedIsCalculated, isCalculated);
+            Assert.AreEqual(expectedShouldCalculate, shouldCalculate);
         }
 
-        private static IEnumerable<TestCaseData> GetHydraulicBoundaryLocationCalculations()
+        private static IEnumerable<TestCaseData> GetCalculations()
         {
+            var outputWithoutGeneralResult = new TestHydraulicBoundaryLocationCalculationOutput(1.0, CalculationConvergence.CalculatedConverged);
+            var outputWithGeneralResult = new TestHydraulicBoundaryLocationCalculationOutput(1.0, new TestGeneralResultSubMechanismIllustrationPoint());
+
             yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation())
-            {
-                InputParameters =
                 {
-                    ShouldIllustrationPointsBeCalculated = true
-                },
-                Output = new TestHydraulicBoundaryLocationCalculationOutput(1.0, CalculationConvergence.CalculatedConverged)
-            }, false);
+                    InputParameters =
+                    {
+                        ShouldIllustrationPointsBeCalculated = true
+                    },
+                    Output = outputWithGeneralResult
+                }, false)
+                .SetName("OutputSufficientScenario1");
 
-            yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation()), false);
+            yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation())
+                {
+                    Output = outputWithoutGeneralResult
+                }, false)
+                .SetName("OutputSufficientScenario2");
 
+            yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation()), true)
+                .SetName("NoOutputScenario1");
+
             yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation())
-            {
-                Output = new TestHydraulicBoundaryLocationCalculationOutput(1.0, CalculationConvergence.CalculatedConverged)
-            }, true);
+                {
+                    InputParameters =
+                    {
+                        ShouldIllustrationPointsBeCalculated = true
+                    }
+                }, true)
+                .SetName("NoOutputScenario2");
 
             yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation())
-            {
-                InputParameters =
                 {
-                    ShouldIllustrationPointsBeCalculated = true
-                },
-                Output = new TestHydraulicBoundaryLocationCalculationOutput(1.0, new TestGeneralResultSubMechanismIllustrationPoint())
-            }, true);
+                    Output = outputWithGeneralResult
+                }, true)
+                .SetName("OutputWithRedundantGeneralResult");
 
             yield return new TestCaseData(new HydraulicBoundaryLocationCalculation(new TestHydraulicBoundaryLocation())
-            {
-                Output = new TestHydraulicBoundaryLocationCalculationOutput(1.0, new TestGeneralResultSubMechanismIllustrationPoint())
-            }, false);
+                {
+                    InputParameters =
+                    {
+                        ShouldIllustrationPointsBeCalculated = true
+                    },
+                    Output = outputWithoutGeneralResult
+                }, true)
+                .SetName("OutputWithMissingGeneralResult");
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Structures/StructuresCalculationTest.cs
===================================================================
diff -u -ra1660e4c72d2ba7a6c97dff29ca732ee292af5f4 -r0e2d1a46c627af6d19cdf21dff840716bac84045
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Structures/StructuresCalculationTest.cs	(.../StructuresCalculationTest.cs)	(revision a1660e4c72d2ba7a6c97dff29ca732ee292af5f4)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Structures/StructuresCalculationTest.cs	(.../StructuresCalculationTest.cs)	(revision 0e2d1a46c627af6d19cdf21dff840716bac84045)
@@ -203,19 +203,22 @@
 
         private static IEnumerable<TestCaseData> GetCalculations()
         {
+            var outputWithoutGeneralResult = new TestStructuresOutput();
+            var outputWithGeneralResult = new TestStructuresOutput(new TestGeneralResultFaultTreeIllustrationPoint());
+
             yield return new TestCaseData(new TestStructuresCalculation
                 {
                     InputParameters =
                     {
                         ShouldIllustrationPointsBeCalculated = true
                     },
-                    Output = new TestStructuresOutput(new TestGeneralResultFaultTreeIllustrationPoint())
+                    Output = outputWithGeneralResult
                 }, false)
                 .SetName("OutputSufficientScenario1");
 
             yield return new TestCaseData(new TestStructuresCalculation
                 {
-                    Output = new TestStructuresOutput()
+                    Output = outputWithoutGeneralResult
                 }, false)
                 .SetName("OutputSufficientScenario2");
 
@@ -233,7 +236,7 @@
 
             yield return new TestCaseData(new TestStructuresCalculation
                 {
-                    Output = new TestStructuresOutput(new TestGeneralResultFaultTreeIllustrationPoint())
+                    Output = outputWithGeneralResult
                 }, true)
                 .SetName("OutputWithRedundantGeneralResult");
 
@@ -243,7 +246,7 @@
                     {
                         ShouldIllustrationPointsBeCalculated = true
                     },
-                    Output = new TestStructuresOutput()
+                    Output = outputWithoutGeneralResult
                 }, true)
                 .SetName("OutputWithMissingGeneralResult");
         }