diff --git a/backend/src/main/java/org/raddatz/familienarchiv/service/PersonService.java b/backend/src/main/java/org/raddatz/familienarchiv/service/PersonService.java
index 8ac9a3bd..52f6231c 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/service/PersonService.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/service/PersonService.java
@@ -70,11 +70,21 @@ public class PersonService {
         return personRepository.save(person);
     }
 
-    @Transactional
-    public Person updatePerson(UUID id, PersonUpdateDTO dto) {
-        if (dto.getBirthYear() != null && dto.getDeathYear() != null && dto.getBirthYear() > dto.getDeathYear()) {
+    private void validateYears(Integer birthYear, Integer deathYear) {
+        if (birthYear != null && birthYear <= 0) {
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Geburtsjahr muss eine positive Zahl sein");
+        }
+        if (deathYear != null && deathYear <= 0) {
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Todesjahr muss eine positive Zahl sein");
+        }
+        if (birthYear != null && deathYear != null && birthYear > deathYear) {
             throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Geburtsjahr darf nicht nach dem Todesjahr liegen");
         }
+    }
+
+    @Transactional
+    public Person updatePerson(UUID id, PersonUpdateDTO dto) {
+        validateYears(dto.getBirthYear(), dto.getDeathYear());
         Person person = personRepository.findById(id)
                 .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Person nicht gefunden"));
         person.setFirstName(dto.getFirstName());
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/service/PersonServiceTest.java b/backend/src/test/java/org/raddatz/familienarchiv/service/PersonServiceTest.java
index f2eb3628..fb0023fe 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/service/PersonServiceTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/service/PersonServiceTest.java
@@ -267,6 +267,56 @@ class PersonServiceTest {
         assertThat(result.getDeathYear()).isEqualTo(1900);
     }
 
+    // ─── Phase 1.3: Year range bounds (> 0) ──────────────────────────────────
+
+    @Test
+    void updatePerson_throwsBadRequest_whenBirthYearIsZero() {
+        UUID id = UUID.randomUUID();
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setFirstName("Anna"); dto.setLastName("Alt"); dto.setBirthYear(0);
+        assertThatThrownBy(() -> personService.updatePerson(id, dto))
+                .isInstanceOf(ResponseStatusException.class)
+                .extracting(e -> ((ResponseStatusException) e).getStatusCode().value())
+                .isEqualTo(400);
+    }
+
+    @Test
+    void updatePerson_throwsBadRequest_whenBirthYearIsNegative() {
+        UUID id = UUID.randomUUID();
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setFirstName("Anna"); dto.setLastName("Alt"); dto.setBirthYear(-5);
+        assertThatThrownBy(() -> personService.updatePerson(id, dto))
+                .isInstanceOf(ResponseStatusException.class)
+                .extracting(e -> ((ResponseStatusException) e).getStatusCode().value())
+                .isEqualTo(400);
+    }
+
+    @Test
+    void updatePerson_throwsBadRequest_whenDeathYearIsZero() {
+        UUID id = UUID.randomUUID();
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setFirstName("Anna"); dto.setLastName("Alt"); dto.setDeathYear(0);
+        assertThatThrownBy(() -> personService.updatePerson(id, dto))
+                .isInstanceOf(ResponseStatusException.class)
+                .extracting(e -> ((ResponseStatusException) e).getStatusCode().value())
+                .isEqualTo(400);
+    }
+
+    @Test
+    void updatePerson_throwsBadRequest_whenDeathYearIsNegative() {
+        UUID id = UUID.randomUUID();
+
+        PersonUpdateDTO dto = new PersonUpdateDTO();
+        dto.setFirstName("Anna"); dto.setLastName("Alt"); dto.setDeathYear(-10);
+        assertThatThrownBy(() -> personService.updatePerson(id, dto))
+                .isInstanceOf(ResponseStatusException.class)
+                .extracting(e -> ((ResponseStatusException) e).getStatusCode().value())
+                .isEqualTo(400);
+    }
+
     // ─── findCorrespondents ──────────────────────────────────────────────────
 
     @Test