diff --git a/backend/app/utils/fallgruppe_map.py b/backend/app/utils/fallgruppe_map.py
new file mode 100644
index 0000000..84b9040
--- /dev/null
+++ b/backend/app/utils/fallgruppe_map.py
@@ -0,0 +1,42 @@
+"""Mapping of CRM 'Modul' strings to internal fallgruppe codes."""
+
+MODUL_TO_FALLGRUPPE: dict[str, str] = {
+    "Zweitmeinung Onkologie": "onko",
+    "Zweitmeinung Kardiologie": "kardio",
+    "Zweitmeinung Intensiv": "intensiv",
+    "Zweitmeinung Gallenblase": "galle",
+    "Zweitmeinung Schilddrüse": "sd",
+}
+
+VALID_FALLGRUPPEN = {"onko", "kardio", "intensiv", "galle", "sd"}
+
+
+def map_modul_to_fallgruppe(modul: str) -> str:
+    """Map CRM Modul string to fallgruppe code.
+
+    Handles exact matches and 'Begutachtung *' patterns.
+    Raises ValueError for unmappable modules.
+    """
+    modul = modul.strip()
+    if modul in MODUL_TO_FALLGRUPPE:
+        return MODUL_TO_FALLGRUPPE[modul]
+
+    modul_lower = modul.lower()
+    # Handle "Begutachtung" variants — derive from keywords
+    if "begutachtung" in modul_lower:
+        keyword_map = [
+            ("onko", "onko"),
+            ("krebs", "onko"),
+            ("tumor", "onko"),
+            ("kardio", "kardio"),
+            ("herz", "kardio"),
+            ("intensiv", "intensiv"),
+            ("galle", "galle"),
+            ("schilddrüse", "sd"),
+            ("schilddruese", "sd"),
+        ]
+        for keyword, gruppe in keyword_map:
+            if keyword in modul_lower:
+                return gruppe
+
+    raise ValueError(f"Cannot map module to fallgruppe: '{modul}'")
diff --git a/backend/app/utils/kw_utils.py b/backend/app/utils/kw_utils.py
new file mode 100644
index 0000000..9571f2a
--- /dev/null
+++ b/backend/app/utils/kw_utils.py
@@ -0,0 +1,50 @@
+"""Calendar week and date utilities."""
+
+from datetime import date
+
+
+def date_to_kw(d: date) -> int:
+    """Return ISO calendar week number."""
+    return d.isocalendar()[1]
+
+
+def date_to_jahr(d: date) -> int:
+    """Return ISO calendar year (can differ from d.year at year boundaries)."""
+    return d.isocalendar()[0]
+
+
+def parse_german_date(s: str) -> date:
+    """Parse German date formats: DD.MM.YY, DD.MM.YYYY, 'DD.MM.YY, HH:MM'.
+
+    Handles edge cases:
+    - Two-digit years: 00-49 -> 2000-2049, 50-99 -> 1950-1999
+    - Invalid dates like '29.08.0196' -> raises ValueError
+    - Leading/trailing whitespace
+    - Comma-separated datetime: '02.02.26, 08:50' -> takes date part only
+    """
+    s = s.strip()
+    if not s:
+        raise ValueError("Empty date string")
+
+    # Split off time part if present (e.g., "02.02.26, 08:50")
+    if "," in s:
+        s = s.split(",")[0].strip()
+
+    parts = s.split(".")
+    if len(parts) != 3:
+        raise ValueError(f"Invalid date format: '{s}'")
+
+    day = int(parts[0])
+    month = int(parts[1])
+    year_str = parts[2].strip()
+    year = int(year_str)
+
+    # Handle 2-digit years
+    if year < 100:
+        year = 2000 + year if year < 50 else 1900 + year
+
+    # Reject obviously wrong years
+    if year < 1900 or year > 2100:
+        raise ValueError(f"Year out of range: {year}")
+
+    return date(year, month, day)
diff --git a/backend/app/utils/validators.py b/backend/app/utils/validators.py
new file mode 100644
index 0000000..2a56ea6
--- /dev/null
+++ b/backend/app/utils/validators.py
@@ -0,0 +1,41 @@
+"""Data validation functions for ICD codes and KVNR."""
+
+import re
+
+ICD_PATTERN = re.compile(r"^[A-Z]\d{2}(\.\d{1,2})?$")
+KVNR_PATTERN = re.compile(r"^[A-Z]\d{9}$")
+
+
+def validate_icd(code: str) -> str:
+    """Validate and normalize a single ICD code. Returns uppercase stripped code."""
+    code = code.strip().upper()
+    if not code:
+        raise ValueError("Empty ICD code")
+    if not ICD_PATTERN.match(code):
+        raise ValueError(f"Invalid ICD code format: '{code}'")
+    return code
+
+
+def split_icd_codes(raw: str) -> list[str]:
+    """Split a string of multiple ICD codes (comma or semicolon separated)."""
+    if not raw or not raw.strip():
+        return []
+    # Split by comma, semicolon, or whitespace+comma combinations
+    codes = re.split(r"[,;]\s*", raw.strip())
+    return [c.strip() for c in codes if c.strip()]
+
+
+def normalize_icd_hauptgruppe(code: str) -> str:
+    """Extract hauptgruppe from ICD code: 'C50.1' -> 'C50'."""
+    code = code.strip().upper()
+    return code[:3] if len(code) >= 3 else code
+
+
+def validate_kvnr(kvnr: str) -> str:
+    """Validate KVNR format (letter + 9 digits). Returns stripped uppercase."""
+    kvnr = kvnr.strip().upper()
+    if not kvnr:
+        raise ValueError("Empty KVNR")
+    if not KVNR_PATTERN.match(kvnr):
+        raise ValueError(f"Invalid KVNR format: '{kvnr}'")
+    return kvnr
diff --git a/backend/tests/test_utils.py b/backend/tests/test_utils.py
new file mode 100644
index 0000000..947495a
--- /dev/null
+++ b/backend/tests/test_utils.py
@@ -0,0 +1,112 @@
+"""Tests for utility functions: fallgruppe mapping, KW/date utils, validators."""
+
+from datetime import date
+
+import pytest
+
+from app.utils.fallgruppe_map import map_modul_to_fallgruppe
+from app.utils.kw_utils import date_to_jahr, date_to_kw, parse_german_date
+from app.utils.validators import (
+    normalize_icd_hauptgruppe,
+    split_icd_codes,
+    validate_icd,
+    validate_kvnr,
+)
+
+
+# ── Fallgruppe mapping ─────────────────────────────────────────────
+
+
+class TestFallgruppeMapping:
+    def test_map_exact_matches(self):
+        assert map_modul_to_fallgruppe("Zweitmeinung Onkologie") == "onko"
+        assert map_modul_to_fallgruppe("Zweitmeinung Kardiologie") == "kardio"
+        assert map_modul_to_fallgruppe("Zweitmeinung Intensiv") == "intensiv"
+        assert map_modul_to_fallgruppe("Zweitmeinung Gallenblase") == "galle"
+        assert map_modul_to_fallgruppe("Zweitmeinung Schilddrüse") == "sd"
+
+    def test_map_with_whitespace(self):
+        assert map_modul_to_fallgruppe(" Zweitmeinung Onkologie ") == "onko"
+
+    def test_map_begutachtung_onko(self):
+        assert map_modul_to_fallgruppe("Begutachtung Onkologie") == "onko"
+
+    def test_map_begutachtung_herz(self):
+        assert map_modul_to_fallgruppe("Begutachtung Herz") == "kardio"
+
+    def test_map_unknown_raises(self):
+        with pytest.raises(ValueError, match="Cannot map module"):
+            map_modul_to_fallgruppe("Unknown Module")
+
+
+# ── KW / Date utils ────────────────────────────────────────────────
+
+
+class TestKWUtils:
+    def test_date_to_kw(self):
+        # 2026-02-24 is a Tuesday in KW 9
+        assert date_to_kw(date(2026, 2, 24)) == 9
+
+    def test_date_to_jahr_boundary(self):
+        # 2025-12-31 is a Wednesday — ISO week 1 of 2026
+        assert date_to_kw(date(2025, 12, 31)) == 1
+        assert date_to_jahr(date(2025, 12, 31)) == 2026
+
+
+class TestParseGermanDate:
+    def test_parse_german_date_ddmmyy(self):
+        assert parse_german_date("02.02.26") == date(2026, 2, 2)
+
+    def test_parse_german_date_ddmmyyyy(self):
+        assert parse_german_date("28.04.1960") == date(1960, 4, 28)
+
+    def test_parse_german_date_with_time(self):
+        assert parse_german_date("02.02.26, 08:50") == date(2026, 2, 2)
+
+    def test_parse_german_date_bad_year(self):
+        with pytest.raises(ValueError, match="Year out of range"):
+            parse_german_date("29.08.0196")
+
+    def test_parse_german_date_empty(self):
+        with pytest.raises(ValueError, match="Empty date string"):
+            parse_german_date("")
+
+
+# ── Validators ──────────────────────────────────────────────────────
+
+
+class TestValidateICD:
+    def test_validate_icd_valid(self):
+        assert validate_icd("C50.1") == "C50.1"
+        assert validate_icd("c50") == "C50"
+
+    def test_validate_icd_invalid(self):
+        with pytest.raises(ValueError, match="Invalid ICD code format"):
+            validate_icd("XYZ")
+        with pytest.raises(ValueError, match="Empty ICD code"):
+            validate_icd("")
+
+
+class TestSplitICDCodes:
+    def test_split_icd_codes_comma(self):
+        assert split_icd_codes("C50.1, C79.5") == ["C50.1", "C79.5"]
+
+    def test_split_icd_codes_semicolon(self):
+        assert split_icd_codes("C50.1;C79.5") == ["C50.1", "C79.5"]
+
+    def test_split_icd_codes_empty(self):
+        assert split_icd_codes("") == []
+
+
+class TestNormalizeHauptgruppe:
+    def test_normalize_hauptgruppe(self):
+        assert normalize_icd_hauptgruppe("C50.1") == "C50"
+
+
+class TestValidateKVNR:
+    def test_validate_kvnr_valid(self):
+        assert validate_kvnr("D410126355") == "D410126355"
+
+    def test_validate_kvnr_invalid(self):
+        with pytest.raises(ValueError, match="Invalid KVNR format"):
+            validate_kvnr("123456789")