diff --git a/app.py b/app.py
index 8c498c6..0b10f53 100644
--- a/app.py
+++ b/app.py
@@ -217,13 +217,20 @@ def api_tage_werktage():
     start = data.get('start')
     end = data.get('end')
     is_werktage = data.get('werktage', False)
+    bundesland = data.get('bundesland')
     try:
         d1 = datetime.strptime(start, '%Y-%m-%d')
         d2 = datetime.strptime(end, '%Y-%m-%d')
         if is_werktage:
             if d1 > d2:
                 d1, d2 = d2, d1
-            tage = int(np.busday_count(d1.date(), (d2 + timedelta(days=1)).date()))
+            holidays = []
+            if bundesland:
+                # Feiertage für alle Jahre im Bereich holen
+                years = set([d1.year, d2.year])
+                for y in years:
+                    holidays.extend(get_feiertage(y, bundesland))
+            tage = int(np.busday_count(d1.date(), (d2 + timedelta(days=1)).date(), holidays=holidays))
         else:
             tage = abs((d2 - d1).days)
         return jsonify({'result': tage})
diff --git a/static/swagger.json b/static/swagger.json
index 4c1ab0a..41966be 100644
--- a/static/swagger.json
+++ b/static/swagger.json
@@ -21,7 +21,12 @@
                 "properties": {
                   "start": { "type": "string", "format": "date" },
                   "end": { "type": "string", "format": "date" },
-                  "werktage": { "type": "boolean", "default": false }
+                  "werktage": { "type": "boolean", "default": false },
+                  "bundesland": { 
+                    "type": "string", 
+                    "description": "Bundesland-Kürzel für Feiertagsberücksichtigung (nur bei werktage=true)",
+                    "enum": ["BW", "BY", "BE", "BB", "HB", "HH", "HE", "MV", "NI", "NW", "RP", "SL", "SN", "ST", "SH", "TH"]
+                  }
                 },
                 "required": ["start", "end"]
               }