diff --git a/SimpliClient.cs b/SimpliClient.cs
index 2510a51..3170575 100644
--- a/SimpliClient.cs
+++ b/SimpliClient.cs
@@ -390,7 +390,8 @@ private ProblemDetails GenerateServerErrorProblemDetails(RestRequest request)
             { "address1", simpliProject.Address1 },
             { "suburb", simpliProject.Suburb },
             { "state", simpliProject.State.GetDescription() },
-            { "country", simpliProject.Country.GetDescription() }
+            { "country", simpliProject.Country.GetDescription() },
+            {"postcode", simpliProject.PostCode}
         };
         if (!string.IsNullOrWhiteSpace(simpliProject.Address2))
         {
@@ -400,10 +401,6 @@ private ProblemDetails GenerateServerErrorProblemDetails(RestRequest request)
         {
             jsonBody.Add("code", simpliProject.Code);
         }
-        if (!string.IsNullOrWhiteSpace(simpliProject.PostCode))
-        {
-            jsonBody.Add("postcode", simpliProject.PostCode);
-        }
 
         request.AddJsonBody(jsonBody);
         
diff --git a/Validation/SimpliProjectValidator.cs b/Validation/SimpliProjectValidator.cs
new file mode 100644
index 0000000..aa82ac7
--- /dev/null
+++ b/Validation/SimpliProjectValidator.cs
@@ -0,0 +1,18 @@
+using FluentValidation;
+using simpliBuild.SWMS.Model;
+
+namespace simpliBuild.Validation;
+
+public class SimpliProjectValidator : AbstractValidator<SimpliProject>
+    {
+    public SimpliProjectValidator()
+    {
+        // Validation rules here
+        RuleFor(project => project.Name).NotEmpty().WithMessage("Project name is required.");
+        RuleFor(project => project.Address1).NotEmpty().WithMessage("Project address is required.");
+        RuleFor(project => project.Suburb).NotEmpty().WithMessage("Project suburb is required.");
+        RuleFor(project => project.PostCode).NotEmpty().WithMessage("Project postcode is required.");
+RuleFor(project => project.State).NotEmpty().WithMessage("Project state is required.");
+RuleFor(project => project.Country).NotEmpty().WithMessage("Project country is required.");
+    }
+}