diff --git a/backend/src/main/java/de/svencarstensen/muh/repository/SampleRepository.java b/backend/src/main/java/de/svencarstensen/muh/repository/SampleRepository.java
index 3259eca..ac10e7e 100644
--- a/backend/src/main/java/de/svencarstensen/muh/repository/SampleRepository.java
+++ b/backend/src/main/java/de/svencarstensen/muh/repository/SampleRepository.java
@@ -12,6 +12,8 @@ public interface SampleRepository extends MongoRepository<Sample, String> {
 
     Optional<Sample> findTopByOrderBySampleNumberDesc();
 
+    Optional<Sample> findTopByOwnerAccountIdOrderBySampleNumberDesc(String ownerAccountId);
+
     List<Sample> findTop12ByOrderByUpdatedAtDesc();
 
     List<Sample> findByFarmerBusinessKeyOrderByCreatedAtDesc(String farmerBusinessKey);
diff --git a/backend/src/main/java/de/svencarstensen/muh/service/SampleService.java b/backend/src/main/java/de/svencarstensen/muh/service/SampleService.java
index 54953fd..7f72a39 100644
--- a/backend/src/main/java/de/svencarstensen/muh/service/SampleService.java
+++ b/backend/src/main/java/de/svencarstensen/muh/service/SampleService.java
@@ -28,6 +28,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 @Service
@@ -67,7 +68,8 @@ public class SampleService {
                 .filter(sample -> !sample.completedAt().isBefore(today.atStartOfDay()))
                 .filter(sample -> sample.completedAt().isBefore(today.plusDays(1).atStartOfDay()))
                 .count();
-        return new DashboardOverview(nextSampleNumber(), openCount, completedToday, recent);
+        String ownerAccountId = authorizationService.accountId(actor);
+        return new DashboardOverview(nextSampleNumber(ownerAccountId), openCount, completedToday, recent);
     }
 
     public LookupResult lookup(String actorId, long sampleNumber) {
@@ -104,9 +106,10 @@ public class SampleService {
                 .findFirst()
                 .orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Landwirt nicht gefunden"));
 
+        String ownerAccountId = authorizationService.accountId(actor);
         Sample sample = new Sample(
                 null,
-                nextSampleNumber(),
+                nextSampleNumber(ownerAccountId),
                 farmer.businessKey(),
                 farmer.name(),
                 farmer.email(),
@@ -513,9 +516,19 @@ public class SampleService {
     }
 
     public long nextSampleNumber() {
+        return nextSampleNumber(null);
+    }
+
+    public long nextSampleNumber(String ownerAccountId) {
+        if (ownerAccountId != null) {
+            Optional<Sample> lastSample = sampleRepository.findTopByOwnerAccountIdOrderBySampleNumberDesc(ownerAccountId);
+            if (lastSample.isPresent()) {
+                return lastSample.get().sampleNumber() + 1;
+            }
+        }
         return sampleRepository.findTopByOrderBySampleNumberDesc()
                 .map(sample -> sample.sampleNumber() + 1)
-                .orElse(100001L);
+                .orElse(10000L);
     }
 
     public Sample loadSampleEntity(String actorId, String id) {