diff --git a/application/CohortManager/src/Functions/Functions.sln b/application/CohortManager/src/Functions/Functions.sln
index 4c262c25fb..2dbb44e554 100644
--- a/application/CohortManager/src/Functions/Functions.sln
+++ b/application/CohortManager/src/Functions/Functions.sln
@@ -220,6 +220,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HttpParserTests", "..\..\..
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FileNameParserTests", "..\..\..\..\tests\UnitTests\SharedTests\FileNameParserTests\FileNameParserTests.csproj", "{0A68E48A-8249-4A74-B5B7-5921017D07BD}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ValidationHelperTests", "..\..\..\..\tests\UnitTests\SharedTests\ValidationHelperTests\ValidationHelperTests.csproj", "{EDB57691-525A-4693-8562-A5E6F4D0A61F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -610,6 +612,10 @@ Global
 		{C86FDA63-AA51-4B5F-A69B-DEF0266E268F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{C86FDA63-AA51-4B5F-A69B-DEF0266E268F}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{C86FDA63-AA51-4B5F-A69B-DEF0266E268F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{EDB57691-525A-4693-8562-A5E6F4D0A61F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{EDB57691-525A-4693-8562-A5E6F4D0A61F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{EDB57691-525A-4693-8562-A5E6F4D0A61F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{EDB57691-525A-4693-8562-A5E6F4D0A61F}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
diff --git a/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.cs b/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.cs
new file mode 100644
index 0000000000..e736a3458f
--- /dev/null
+++ b/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.cs
@@ -0,0 +1,78 @@
+namespace NHS.CohortManager.Tests.Shared;
+
+
+using Common;
+
+[TestClass]
+public class ValidationHelperTests
+{ 
+    [TestMethod]
+    [DataRow("20000101")]               //  yyyymmdd
+    [DataRow("200001")]                 //  yyyymm
+    [DataRow("2000-01-01")]             //  yyyy-mm-dd
+    [DataRow("01/01/2000 12:00:00")]    //  dd/mm/yyyy hh:mm:ss
+    [DataRow("2000")]                   //  yyyy
+    public void ValidatePastDate_ValidInput_ReturnTrue(string date)
+    {
+        //No Arrange
+        //Act
+        var actual = ValidationHelper.ValidatePastDate(date);
+
+        //Assert
+        bool expected = true;
+        Assert.AreEqual(actual, expected);
+    }
+
+    [TestMethod]
+    [DataRow(null)]                     //  null
+    [DataRow("20300101")]               //  future date
+    [DataRow("2000-01-32")]             //  date doesn't exist
+    [DataRow("1/13/2000 12:00:00 01")]  //  d/mm/yyyy hh:mm:ss tt
+    [DataRow("01/01/2000 25:00:00 01")] //  dd/mm/yyyy hh:mm:ss tt
+    [DataRow("-2000")]                  //  negative year
+    public void ValidatePastDate_InvalidInput_ReturnFalse(string date) 
+    {
+        //No Arrange
+        //Act
+        var actual = ValidationHelper.ValidatePastDate(date);
+
+        //Assert
+        bool expected = false;
+        Assert.AreEqual(actual, expected);
+    }
+
+    [TestMethod]
+    [DataRow("8919361401")]     // These are random valid NHS numbers created by https://data-gorilla.uk/en/healthcare/nhs-number/
+    [DataRow("4539728490")]     // This does not contain PII.
+    [DataRow("1056154497")]
+    [DataRow("1201484383")]
+    [DataRow("8325769629")]
+    public void ValidateNHSNumber_ValidInput_ReturnTrue(string nhsNumber)
+    {
+        //No Arrange
+        //Act
+        var actual = ValidationHelper.ValidateNHSNumber(nhsNumber);
+
+        //Assert
+        bool expected = true;
+        Assert.AreEqual(actual, expected);
+    }
+
+    [TestMethod]
+    [DataRow(null)]
+    [DataRow("1234567890")]  
+    [DataRow("-1234567890")]    
+    [DataRow("1a2b3c4d5e")]
+    [DataRow("123")]
+    [DataRow("0000000000")]
+    public void ValidateNHSNumber_InvalidInput_ReturnFalse(string nhsNumber) 
+    {
+        //No Arrange
+        //Act
+        var actual = ValidationHelper.ValidateNHSNumber(nhsNumber);
+
+        //Assert
+        bool expected = false;
+        Assert.AreEqual(actual, expected);
+    }   
+}
\ No newline at end of file
diff --git a/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.csproj b/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.csproj
new file mode 100644
index 0000000000..6e5181e471
--- /dev/null
+++ b/tests/UnitTests/SharedTests/ValidationHelperTests/ValidationHelperTests.csproj
@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.1.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.1.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="../../../../application/CohortManager/src/Functions/Shared/Common/Common.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Microsoft.VisualStudio.TestTools.UnitTesting" />
+  </ItemGroup>
+
+</Project>