diff --git a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/config/AdminDataInitializer.java b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/config/AdminDataInitializer.java
index bd63b95..4741133 100644
--- a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/config/AdminDataInitializer.java
+++ b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/config/AdminDataInitializer.java
@@ -13,6 +13,7 @@ import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Component;
 
 import java.security.SecureRandom;
+import java.time.LocalDateTime;
 
 @Component
 @Profile("dev")
@@ -60,6 +61,7 @@ public class AdminDataInitializer implements CommandLineRunner {
         admin.setLastName(ADMIN_LAST_NAME);
         admin.setParticipantType(ParticipantType.PRIVATE);
         admin.setRole(UserRole.ADMIN);
+        admin.setCreatedAt(LocalDateTime.now());
         admin.setStatus(RegistrationStatus.APPROVED);
         admin.setEnabled(true);
         admin.setEmailVerified(true);
@@ -74,6 +76,7 @@ public class AdminDataInitializer implements CommandLineRunner {
         testUser.setLastName("Benutzer");
         testUser.setParticipantType(ParticipantType.PRIVATE);
         testUser.setRole(UserRole.MEMBER);
+        testUser.setCreatedAt(LocalDateTime.now());
         testUser.setStatus(RegistrationStatus.PENDING);
         testUser.setEnabled(false);
         testUser.setEmailVerified(true);
diff --git a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/domain/User.java b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/domain/User.java
index 4645312..2853618 100644
--- a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/domain/User.java
+++ b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/domain/User.java
@@ -59,6 +59,9 @@ public class User implements UserDetails {
     @Column(nullable = false)
     private RegistrationStatus status = RegistrationStatus.PENDING;
 
+    @Column(updatable = false)
+    private LocalDateTime createdAt;
+
     @Column(nullable = false)
     private boolean enabled = false;
 
diff --git a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/mapper/UserMapper.java b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/mapper/UserMapper.java
index b96db11..cead5c2 100644
--- a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/mapper/UserMapper.java
+++ b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/mapper/UserMapper.java
@@ -27,6 +27,7 @@ public interface UserMapper {
     @Mapping(target = "verificationToken",  ignore = true)
     @Mapping(target = "passwordResetToken", ignore = true)
     @Mapping(target = "passwordResetTokenExpiry", ignore = true)
+    @Mapping(target = "createdAt", ignore = true)
     User mapToEntity(IamDtos.RegistrationRequest request, @MappingTarget User user);
 
 
diff --git a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/service/AuthService.java b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/service/AuthService.java
index 4358cba..4549219 100644
--- a/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/service/AuthService.java
+++ b/eeg_backend/src/main/java/at/mueller/eeg/backend/iam/service/AuthService.java
@@ -19,6 +19,7 @@ import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.time.Instant;
+import java.time.LocalDateTime;
 import java.time.temporal.ChronoUnit;
 import java.util.UUID;
 
@@ -73,6 +74,7 @@ public class AuthService {
         }
 
         User newUser = userMapper.mapToEntity(request, new User());
+        newUser.setCreatedAt(LocalDateTime.now());
         String token = UUID.randomUUID().toString();
         newUser.setVerificationToken(token);
 
diff --git a/eeg_backend/src/test/java/at/mueller/eeg/backend/iam/domain/UserTest.java b/eeg_backend/src/test/java/at/mueller/eeg/backend/iam/domain/UserTest.java
new file mode 100644
index 0000000..e0d0c03
--- /dev/null
+++ b/eeg_backend/src/test/java/at/mueller/eeg/backend/iam/domain/UserTest.java
@@ -0,0 +1,36 @@
+package at.mueller.eeg.backend.iam.domain;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDateTime;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class UserTest {
+
+    @Test
+    void createdAtFieldExists() {
+        User user = new User();
+        LocalDateTime now = LocalDateTime.now();
+
+        user.setCreatedAt(now);
+
+        assertEquals(now, user.getCreatedAt());
+    }
+
+    @Test
+    void createdAtIsNotUpdatable() throws NoSuchFieldException {
+        var field = User.class.getDeclaredField("createdAt");
+        var column = field.getAnnotation(jakarta.persistence.Column.class);
+
+        assertNotNull(column, "@Column annotation must be present on createdAt");
+        assertFalse(column.updatable(), "createdAt must be non-updatable");
+    }
+
+    @Test
+    void createdAtDefaultIsNull() {
+        User user = new User();
+
+        assertNull(user.getCreatedAt(), "createdAt should default to null (not auto-generated)");
+    }
+}