diff --git a/src/Application/Features/Assessments/Commands/BeginAssessment.cs b/src/Application/Features/Assessments/Commands/BeginAssessment.cs
index 8fbb8213..670359da 100644
--- a/src/Application/Features/Assessments/Commands/BeginAssessment.cs
+++ b/src/Application/Features/Assessments/Commands/BeginAssessment.cs
@@ -1,5 +1,6 @@
 using System.Text.Json.Serialization;
 using Cfo.Cats.Application.Common.Security;
+using Cfo.Cats.Application.Common.Validators;
 using Cfo.Cats.Application.Features.Assessments.Caching;
 using Cfo.Cats.Application.Features.Assessments.DTOs;
 using Cfo.Cats.Application.Features.Assessments.DTOs.V1.Pathways.Education;
@@ -78,12 +79,30 @@ public async Task<Result<Guid>> Handle(Command request, CancellationToken cancel
 
     public class Validator : AbstractValidator<Command>
     {
-        public Validator()
+        private readonly IUnitOfWork _unitOfWork;
+
+        public Validator(IUnitOfWork unitOfWork)
         {
+            _unitOfWork = unitOfWork;
+
             RuleFor(c => c.ParticipantId)
                 .MinimumLength(9)
-                .MaximumLength(9);
+                .MaximumLength(9)
+                .Matches(ValidationConstants.AlphaNumeric)
+                .WithMessage(string.Format(ValidationConstants.AlphaNumericMessage, "Participant Id"));
+
+            RuleFor(c => c.ParticipantId)
+                .MustAsync(Exist)
+                .WithMessage("Participant not found")
+                .MustAsync(HaveEnrolmentLocation)
+                .WithMessage("Participant must have an enrolment location");
         }
+
+        private async Task<bool> Exist(string participantId, CancellationToken cancellationToken)
+            => await _unitOfWork.DbContext.Participants.AnyAsync(e => e.Id == participantId, cancellationToken);
+
+        private async Task<bool> HaveEnrolmentLocation(string participantId, CancellationToken cancellationToken)
+            => await _unitOfWork.DbContext.Participants.AnyAsync(e => e.Id == participantId && e.EnrolmentLocation != null, cancellationToken);
     }
 
 }
diff --git a/src/Application/Features/Assessments/Commands/SaveAssessment.cs b/src/Application/Features/Assessments/Commands/SaveAssessment.cs
index 95fc78ba..b347e28f 100644
--- a/src/Application/Features/Assessments/Commands/SaveAssessment.cs
+++ b/src/Application/Features/Assessments/Commands/SaveAssessment.cs
@@ -1,4 +1,5 @@
 using Cfo.Cats.Application.Common.Security;
+using Cfo.Cats.Application.Common.Validators;
 using Cfo.Cats.Application.Features.Assessments.Caching;
 using Cfo.Cats.Application.Features.Assessments.DTOs;
 using Cfo.Cats.Application.SecurityConstants;
@@ -75,4 +76,33 @@ public async Task<Result> Handle(Command request, CancellationToken cancellation
         }
     }
 
+    public class Validator : AbstractValidator<Command>
+    {
+        private readonly IUnitOfWork _unitOfWork;
+
+        public Validator(IUnitOfWork unitOfWork)
+        {
+            _unitOfWork = unitOfWork;
+
+            RuleFor(c => c.Assessment.Id)
+                .MustAsync(Exist)
+                .WithMessage("Assessment not found");
+
+            RuleFor(c => c.Assessment.ParticipantId)
+                .MustAsync(Exist)
+                .WithMessage("Participant not found")
+                .MustAsync(HaveEnrolmentLocation)
+                .WithMessage("Participant must have an enrolment location");
+        }
+
+        private async Task<bool> Exist(Guid assessmentId, CancellationToken cancellationToken)
+            => await _unitOfWork.DbContext.ParticipantAssessments.AnyAsync(e => e.Id == assessmentId, cancellationToken);
+
+        private async Task<bool> Exist(string participantId, CancellationToken cancellationToken)
+            => await _unitOfWork.DbContext.Participants.AnyAsync(e => e.Id == participantId, cancellationToken);
+
+        private async Task<bool> HaveEnrolmentLocation(string participantId, CancellationToken cancellationToken)
+            => await _unitOfWork.DbContext.Participants.AnyAsync(e => e.Id == participantId && e.EnrolmentLocation != null, cancellationToken);
+
+    }
 }
diff --git a/src/Server.UI/Pages/Participants/Components/CaseSummary.razor.cs b/src/Server.UI/Pages/Participants/Components/CaseSummary.razor.cs
index 2214a7a0..11335d14 100644
--- a/src/Server.UI/Pages/Participants/Components/CaseSummary.razor.cs
+++ b/src/Server.UI/Pages/Participants/Components/CaseSummary.razor.cs
@@ -35,12 +35,17 @@ public async Task BeginAssessment()
         {
             ParticipantId = ParticipantSummaryDto.Id
         };
+
         var result = await GetNewMediator().Send(command);
 
         if (result.Succeeded)
         {
             Navigation.NavigateTo($"/pages/participants/{ParticipantSummaryDto.Id}/assessment/{result.Data}");
         }
+        else
+        {
+            Snackbar.Add(result.ErrorMessage, Severity.Error);
+        }
     }
     
     public void ContinueAssessment()