diff --git a/backend/routes/invoices.py b/backend/routes/invoices.py
index 66a6d63..dd71609 100644
--- a/backend/routes/invoices.py
+++ b/backend/routes/invoices.py
@@ -599,7 +599,7 @@ def pay_invoice(invoice_id: int, data: PayBody, admin=Depends(require_admin)):
 
 
 @router.post("/{invoice_id}/cancel")
-def cancel_invoice(invoice_id: int, data: CancelBody, admin=Depends(require_admin)):
+async def cancel_invoice(invoice_id: int, data: CancelBody, admin=Depends(require_admin)):
     with db() as conn:
         row = conn.execute("SELECT * FROM invoices WHERE id=?", (invoice_id,)).fetchone()
         if not row:
@@ -613,4 +613,66 @@ def cancel_invoice(invoice_id: int, data: CancelBody, admin=Depends(require_admi
             (now, data.reason, cancellation_number, invoice_id)
         )
         row = conn.execute("SELECT * FROM invoices WHERE id=?", (invoice_id,)).fetchone()
-    return _row_to_dict(row)
+        items = _fetch_items(conn, invoice_id)
+
+    invoice = _row_to_dict(row)
+
+    # Storno-PDF: invoice-Dict als Stornobeleg aufbereiten
+    storno_invoice = dict(invoice)
+    storno_invoice["invoice_number"] = cancellation_number
+    storno_invoice["notes"] = (
+        f"Stornierung zu Rechnung {invoice['invoice_number']}\n"
+        f"Grund: {data.reason}"
+    )
+    storno_invoice["amount_net"]            = -invoice["amount_net"]
+    storno_invoice["discount_amount"]       = -invoice.get("discount_amount", 0)
+    storno_invoice["amount_after_discount"] = -invoice["amount_after_discount"]
+    storno_invoice["tax_amount"]            = -invoice.get("tax_amount", 0)
+    storno_invoice["amount_gross"]          = -invoice["amount_gross"]
+    for item in items:
+        item["unit_price"] = -item["unit_price"]
+        item["total"]      = -item["total"]
+
+    try:
+        pdf_bytes = _generate_pdf(storno_invoice, items)
+    except Exception as e:
+        logger.error(f"Storno-PDF fehlgeschlagen: {e}")
+        return _row_to_dict(row)
+
+    filename = f"{cancellation_number}_banyaro.pdf"
+
+    try:
+        await _save_to_paperless(pdf_bytes, cancellation_number, filename)
+    except Exception as e:
+        logger.warning(f"Storno Paperless fehlgeschlagen: {e}")
+
+    # Mail an Kunden
+    try:
+        body_html = mailer.email_html(f"""
+        <p style="margin:0 0 16px">Hallo <b>{invoice['recipient_name']}</b>,</p>
+        <p style="margin:0 0 16px">
+          Ihre Rechnung <b>{invoice['invoice_number']}</b> wurde storniert
+          (Stornonummer: <b>{cancellation_number}</b>).
+        </p>
+        <p style="margin:0 0 8px;color:#666;font-size:13px">Grund: {data.reason}</p>
+        <p style="margin:0;color:#666;font-size:13px">
+          Das Stornodokument liegt diesem Schreiben bei.
+        </p>
+        """)
+        plain = (
+            f"Hallo {invoice['recipient_name']},\n\n"
+            f"Ihre Rechnung {invoice['invoice_number']} wurde storniert "
+            f"(Stornonummer: {cancellation_number}).\n"
+            f"Grund: {data.reason}\n"
+        )
+        await mailer.send_email(
+            to=invoice["recipient_email"],
+            subject=f"Stornierung Rechnung {invoice['invoice_number']} — Ban Yaro",
+            html=body_html,
+            plain=plain,
+            attachments=[{"filename": filename, "content": pdf_bytes, "content_type": "application/pdf"}],
+        )
+    except Exception as e:
+        logger.error(f"Storno-Mail fehlgeschlagen: {e}")
+
+    return invoice
diff --git a/docker-compose.staging.yml b/docker-compose.staging.yml
index d9ef97e..38b4182 100644
--- a/docker-compose.staging.yml
+++ b/docker-compose.staging.yml
@@ -8,6 +8,7 @@ services:
     volumes:
       - ./data:/data
       - /volume1/docker/banyaro/data/media:/prod-media:ro
+      - /volume1/scaninput:/scaninput
     env_file:
       - .env
     environment: