diff --git a/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java b/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
index 84caab27..5c6b6d95 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
@@ -15,6 +15,10 @@ public enum ErrorCode {
     ALIAS_NOT_FOUND,
     /** The submitted personType value is not allowed (e.g. SKIP is import-only). 400 */
     INVALID_PERSON_TYPE,
+    /** A person's birth date is after their death date. 400 */
+    BIRTH_AFTER_DEATH,
+    /** A life date and its precision are incoherent: date present with UNKNOWN precision, or precision set without a date. 400 */
+    INVALID_DATE_PRECISION,
     // --- Documents ---
     /** A document with the given ID does not exist. 404 */
     DOCUMENT_NOT_FOUND,
diff --git a/frontend/messages/de.json b/frontend/messages/de.json
index bfc2d084..d6c9a0ce 100644
--- a/frontend/messages/de.json
+++ b/frontend/messages/de.json
@@ -643,6 +643,8 @@
 	"error_alias_not_found": "Der Namensalias wurde nicht gefunden.",
 	"error_invalid_person_type": "Der angegebene Personentyp ist ungültig.",
 	"error_invalid_date_range": "Das Enddatum darf nicht vor dem Startdatum liegen.",
+	"error_birth_after_death": "Geburtsdatum muss vor dem Sterbedatum liegen. Tipp: Falls nur das Todesjahr bekannt ist und der Geburtstag spät im selben Jahr lag, bitte das Folgejahr eintragen.",
+	"error_invalid_date_precision": "Datum und Genauigkeit stimmen nicht überein",
 	"validation_last_name_required": "Nachname ist Pflichtfeld.",
 	"validation_first_name_required": "Vorname ist Pflichtfeld.",
 	"error_ocr_service_unavailable": "Der OCR-Dienst ist nicht verfügbar.",
diff --git a/frontend/messages/en.json b/frontend/messages/en.json
index 2ec576aa..c330c78d 100644
--- a/frontend/messages/en.json
+++ b/frontend/messages/en.json
@@ -643,6 +643,8 @@
 	"error_alias_not_found": "The name alias was not found.",
 	"error_invalid_person_type": "The specified person type is not valid.",
 	"error_invalid_date_range": "The end date must not be before the start date.",
+	"error_birth_after_death": "Birth date must be before death date. Tip: if only the death year is known and the birthday is late in the same year, enter the following year.",
+	"error_invalid_date_precision": "Date and precision do not match",
 	"validation_last_name_required": "Last name is required.",
 	"validation_first_name_required": "First name is required.",
 	"error_ocr_service_unavailable": "The OCR service is not available.",
diff --git a/frontend/messages/es.json b/frontend/messages/es.json
index 0bcd27ac..e6837b83 100644
--- a/frontend/messages/es.json
+++ b/frontend/messages/es.json
@@ -643,6 +643,8 @@
 	"error_alias_not_found": "No se encontro el alias de nombre.",
 	"error_invalid_person_type": "El tipo de persona especificado no es válido.",
 	"error_invalid_date_range": "La fecha final no puede ser anterior a la inicial.",
+	"error_birth_after_death": "La fecha de nacimiento debe ser anterior a la de defunción.",
+	"error_invalid_date_precision": "La fecha y la precisión no coinciden",
 	"validation_last_name_required": "El apellido es obligatorio.",
 	"validation_first_name_required": "El nombre es obligatorio.",
 	"error_ocr_service_unavailable": "El servicio OCR no está disponible.",
diff --git a/frontend/src/lib/shared/errors.ts b/frontend/src/lib/shared/errors.ts
index e06f37d4..344fc08c 100644
--- a/frontend/src/lib/shared/errors.ts
+++ b/frontend/src/lib/shared/errors.ts
@@ -8,6 +8,8 @@ export type ErrorCode =
 	| 'PERSON_NOT_FOUND'
 	| 'ALIAS_NOT_FOUND'
 	| 'INVALID_PERSON_TYPE'
+	| 'BIRTH_AFTER_DEATH'
+	| 'INVALID_DATE_PRECISION'
 	| 'INVALID_DATE_RANGE'
 	| 'DOCUMENT_NOT_FOUND'
 	| 'DOCUMENT_NO_FILE'
@@ -96,6 +98,10 @@ export function getErrorMessage(code: ErrorCode | string | undefined): string {
 			return m.error_alias_not_found();
 		case 'INVALID_PERSON_TYPE':
 			return m.error_invalid_person_type();
+		case 'BIRTH_AFTER_DEATH':
+			return m.error_birth_after_death();
+		case 'INVALID_DATE_PRECISION':
+			return m.error_invalid_date_precision();
 		case 'INVALID_DATE_RANGE':
 			return m.error_invalid_date_range();
 		case 'DOCUMENT_NOT_FOUND':