diff --git a/backend/routes/expenses.py b/backend/routes/expenses.py
index 9a34f27..9e32e43 100644
--- a/backend/routes/expenses.py
+++ b/backend/routes/expenses.py
@@ -12,7 +12,15 @@ from auth import get_current_user
 router = APIRouter()
 logger = logging.getLogger(__name__)
 
-KATEGORIEN = {"tierarzt", "futter", "zubehoer", "versicherung", "sitter", "sonstiges"}
+KATEGORIE_META = {
+    "futter":       {"label": "Futter",       "color": "#f59e0b"},
+    "tierarzt":     {"label": "Tierarzt",     "color": "#ef4444"},
+    "zubehoer":     {"label": "Zubehör",      "color": "#8b5cf6"},
+    "versicherung": {"label": "Versicherung", "color": "#3b82f6"},
+    "sitter":       {"label": "Sitter",       "color": "#10b981"},
+    "sonstiges":    {"label": "Sonstiges",    "color": "#6b7280"},
+}
+KATEGORIEN = set(KATEGORIE_META.keys())
 
 
 # ------------------------------------------------------------------
@@ -75,6 +83,18 @@ def _serialize(row) -> dict:
     return dict(row)
 
 
+# ------------------------------------------------------------------
+# GET /api/expenses/categories — gültige Kategorien (id + label + color)
+# Single source of truth für PWA und mobile Clients.
+# ------------------------------------------------------------------
+@router.get("/categories")
+async def list_categories():
+    return [
+        {"id": key, **meta}
+        for key, meta in KATEGORIE_META.items()
+    ]
+
+
 # ------------------------------------------------------------------
 # GET /api/expenses/summary — Monats- und Jahressummen
 # WICHTIG: Diese Route muss VOR /{id} stehen!