diff --git a/app/schemas.py b/app/schemas.py
index 7b2190c..ac7f96c 100644
--- a/app/schemas.py
+++ b/app/schemas.py
@@ -1,5 +1,8 @@
+import re
+from datetime import date
 from typing import Literal
-from pydantic import BaseModel, Field
+
+from pydantic import BaseModel, Field, field_validator
 
 
 class EndpointCapabilities(BaseModel):
@@ -127,8 +130,37 @@ class EmergencyRequest(BaseModel):
     device: DeviceInfo | None = None
 
 
+# Format-Validierung der Notfall-Profilfelder (spiegelt die Frontend-Prüfung).
+_PLZ_RE = re.compile(r"^\d{5}$")
+_PHONE_RE = re.compile(r"^\+?[\d\s/().\-]{6,20}$")
+_EMAIL_RE = re.compile(r"^[^\s@]+@[^\s@]+\.[^\s@]+$")
+_DATE_RE = re.compile(r"^(\d{2})\.(\d{2})\.(\d{4})$")
+
+
+def _valid_german_date(v: str) -> bool:
+    m = _DATE_RE.match(v)
+    if not m:
+        return False
+    d, mo, y = int(m.group(1)), int(m.group(2)), int(m.group(3))
+    if not (1900 <= y <= 2100):
+        return False
+    try:
+        date(y, mo, d)
+    except ValueError:
+        return False
+    return True
+
+
+def _csv_all(v: str, rx: "re.Pattern") -> bool:
+    return all(rx.match(p.strip()) for p in v.split(",") if p.strip())
+
+
 class AdminUserPrefsUpdate(BaseModel):
-    """Admin setzt Nutzer-Einstellungen: erlaubte Sprachen + Notfall-Profil."""
+    """Admin setzt Nutzer-Einstellungen: erlaubte Sprachen + Notfall-Profil.
+
+    Optionale Felder dürfen leer/None sein; nicht-leere Werte werden auf ihr
+    Format geprüft (serverseitige Härtung zusätzlich zur Frontend-Validierung).
+    """
     allowed_languages: str | None = None
     # Notfall-Profil (in user.prefs gespeichert, fließt in die Notruf-Meldungen ein)
     full_name: str | None = None
@@ -143,6 +175,41 @@ class AdminUserPrefsUpdate(BaseModel):
     emergency_phones: str | None = None     # Kontakt-Telefon(e), CSV
     location_consent: bool | None = None    # Standort im Notfall mitsenden?
 
+    @field_validator("postal_code")
+    @classmethod
+    def _check_plz(cls, v):
+        if v and not _PLZ_RE.match(v.strip()):
+            raise ValueError("PLZ muss genau 5 Ziffern sein")
+        return v
+
+    @field_validator("phone_mobile", "phone_landline")
+    @classmethod
+    def _check_phone(cls, v):
+        if v and not _PHONE_RE.match(v.strip()):
+            raise ValueError("ungültige Telefonnummer")
+        return v
+
+    @field_validator("birth_date")
+    @classmethod
+    def _check_date(cls, v):
+        if v and not _valid_german_date(v.strip()):
+            raise ValueError("Geburtsdatum muss TT.MM.JJJJ (gültiges Datum) sein")
+        return v
+
+    @field_validator("emergency_contacts")
+    @classmethod
+    def _check_emails(cls, v):
+        if v and not _csv_all(v, _EMAIL_RE):
+            raise ValueError("Kontakt-E-Mail(s): ungültige Adresse")
+        return v
+
+    @field_validator("emergency_phones")
+    @classmethod
+    def _check_phones_csv(cls, v):
+        if v and not _csv_all(v, _PHONE_RE):
+            raise ValueError("Kontakt-Telefon(e): ungültige Nummer")
+        return v
+
 
 class UserAdminUpdate(BaseModel):
     """Admin schaltet Admin-Rechte für einen Nutzer ein/aus."""
diff --git a/tests/test_admin_prefs_validation.py b/tests/test_admin_prefs_validation.py
new file mode 100644
index 0000000..a62c211
--- /dev/null
+++ b/tests/test_admin_prefs_validation.py
@@ -0,0 +1,36 @@
+import pytest
+from pydantic import ValidationError
+
+from app.schemas import AdminUserPrefsUpdate
+
+
+def test_valid_profile_passes():
+    AdminUserPrefsUpdate(
+        full_name="Frieda Schlüter", postal_code="50670",
+        phone_mobile="+4915127747511", phone_landline="040 123456",
+        birth_date="14.02.1976",
+        emergency_contacts="a@b.de, c@d.com",
+        emergency_phones="+4915127747511, 040 12345",
+        location_consent=True,
+    )
+
+
+def test_empty_and_none_pass():
+    # Leere/None-Felder gelten als konform (optional).
+    AdminUserPrefsUpdate(postal_code="", phone_mobile="", birth_date="",
+                         emergency_contacts="", emergency_phones=None)
+
+
+@pytest.mark.parametrize("field,value", [
+    ("postal_code", "123"),
+    ("postal_code", "abcde"),
+    ("phone_mobile", "hallo"),
+    ("phone_landline", "xx"),
+    ("birth_date", "1976-02-14"),
+    ("birth_date", "31.02.2020"),
+    ("emergency_contacts", "a@b.de, nope"),
+    ("emergency_phones", "kein-telefon!!"),
+])
+def test_invalid_rejected(field, value):
+    with pytest.raises(ValidationError):
+        AdminUserPrefsUpdate(**{field: value})