diff --git a/application/CohortManager/src/Functions/CohortDistributionServices/TransformDataService/TransformDataLookupFacade.cs b/application/CohortManager/src/Functions/CohortDistributionServices/TransformDataService/TransformDataLookupFacade.cs
index 27f688bf3c..984a84162a 100644
--- a/application/CohortManager/src/Functions/CohortDistributionServices/TransformDataService/TransformDataLookupFacade.cs
+++ b/application/CohortManager/src/Functions/CohortDistributionServices/TransformDataService/TransformDataLookupFacade.cs
@@ -60,14 +60,22 @@ public async Task<HashSet<string>> GetCachedExcludedSMUValues()
 
         return excludedSMUData!;
     }
+
     public bool ValidateOutcode(string postcode)
     {
-        string outcode = ValidationHelper.ParseOutcode(postcode)
+        var parsedOutCode = ValidationHelper.ParseOutcode(postcode);
+        _ = parsedOutCode.outcode
             ?? throw new TransformationException("Postcode format invalid");
 
-        var result = _outcodeClient.GetSingle(outcode).Result;
+        // we can bypass checking the database if it's a dummy postcode
+        if (parsedOutCode.isDummyPostCode)
+        {
+            return true;
+        }
 
+        var result = _outcodeClient.GetSingle(parsedOutCode.outcode).Result;
         return result != null;
+
     }
 
     /// <summary>
@@ -83,7 +91,7 @@ public bool ValidateLanguageCode(string languageCode)
 
     public string GetBsoCode(string postcode)
     {
-        string outcode = ValidationHelper.ParseOutcode(postcode)
+        string outcode = ValidationHelper.ParseOutcode(postcode).outcode
             ?? throw new TransformationException("Postcode format invalid");
 
         var result = _outcodeClient.GetSingle(outcode).Result;
diff --git a/application/CohortManager/src/Functions/ScreeningValidationService/LookupValidation/DataLookupFacadeBreastScreening.cs b/application/CohortManager/src/Functions/ScreeningValidationService/LookupValidation/DataLookupFacadeBreastScreening.cs
index a765e9a5e9..1c2536c3e4 100644
--- a/application/CohortManager/src/Functions/ScreeningValidationService/LookupValidation/DataLookupFacadeBreastScreening.cs
+++ b/application/CohortManager/src/Functions/ScreeningValidationService/LookupValidation/DataLookupFacadeBreastScreening.cs
@@ -53,7 +53,7 @@ public bool ValidateOutcode(string postcode)
     {
         var outcode = ValidationHelper.ParseOutcode(postcode);
         _logger.LogInformation("Validating Outcode: {Outcode}", outcode);
-        var result = _outcodeClient.GetSingle(outcode).Result;
+        var result = _outcodeClient.GetSingle(outcode.outcode!).Result;
 
         return result != null;
     }
diff --git a/application/CohortManager/src/Functions/Shared/Common/ValidationHelper.cs b/application/CohortManager/src/Functions/Shared/Common/ValidationHelper.cs
index 76cbdfe34a..318266a15d 100644
--- a/application/CohortManager/src/Functions/Shared/Common/ValidationHelper.cs
+++ b/application/CohortManager/src/Functions/Shared/Common/ValidationHelper.cs
@@ -1,7 +1,10 @@
 namespace Common;
 
 using System.Globalization;
+using System.Linq.Expressions;
 using System.Text.RegularExpressions;
+using Hl7.Fhir.Validation;
+using Model;
 
 public static class ValidationHelper
 {
@@ -100,31 +103,36 @@ public static bool ValidatePostcode(string postcode)
     }
 
     /// <summary>
-    /// Gets the outcode (1st part of postcode) from the postcode.
+    /// Gets the outcode (1st part of postcode) from the postcode and if the postcode is a dummy code
     /// </summary>
     /// <param name="postcode">a non-null string representing the postcode</param>
     /// <remarks>
     /// Works for valid UK postcodes and dummy postcodes.
     /// Works with or without a space separator between outcode and incode.
     /// </remarks>
-    public static string? ParseOutcode(string postcode)
+    public static (string? outcode, bool isDummyPostCode) ParseOutcode(string postcode)
     {
-        if (postcode == "ZZZSECUR")
-        {
-            return postcode;
-        }
-
         string pattern = @"^([A-Za-z][A-Za-z]?[0-9][A-Za-z0-9]?) ?[0-9][A-Za-z]{2}$";
+        string specialDummyOutCodePattern = "^ZZ99|^ZZZSECUR$";
 
         Match match = Regex.Match(postcode, pattern, RegexOptions.IgnoreCase, TimeSpan.FromSeconds(2));
+        Match dummyOutCodePattern = Regex.Match(postcode, specialDummyOutCodePattern, RegexOptions.IgnoreCase, TimeSpan.FromSeconds(2));
+
+        if (dummyOutCodePattern.Success)
+        {
+            return (postcode, true);
+        }
+
         if (!match.Success)
         {
-            return null;
+            return (null, false);
         }
 
+
+
         string outcode = match.Groups[1].Value;
 
-        return outcode;
+        return (outcode, false);
     }
 
     private static bool ParseInt32(char value, out int integerValue)
diff --git a/tests/UnitTests/TransformDataServiceTests/TransformDataServiceTests/TransformDataLookupFacadeTests.cs b/tests/UnitTests/TransformDataServiceTests/TransformDataServiceTests/TransformDataLookupFacadeTests.cs
index 2e85299567..9697c0a5ac 100644
--- a/tests/UnitTests/TransformDataServiceTests/TransformDataServiceTests/TransformDataLookupFacadeTests.cs
+++ b/tests/UnitTests/TransformDataServiceTests/TransformDataServiceTests/TransformDataLookupFacadeTests.cs
@@ -95,6 +95,23 @@ public void ValidateOutcode_OutcodeNotFound_ReturnFalse()
         Assert.IsFalse(result);
     }
 
+    [TestMethod]
+    public void ValidateOutcode_OutCodeIsSpecial_ReturnTrue()
+    {
+        // Arrange
+        _outcodeClientMock
+            .Setup(x => x.GetSingle(It.IsAny<string>()))
+            .ReturnsAsync((BsSelectOutCode)null);
+
+        string postcode = "ZZZSECUR";
+
+        // Act
+        bool result = _sut.ValidateOutcode(postcode);
+
+        // Assert
+        Assert.IsTrue(result);
+    }
+
     [TestMethod]
     [DataRow("")]
     [DataRow("ABC123")]