diff --git a/.github/copilot-tasks.md b/.github/copilot-tasks.md
index aa222bf..a43e8ed 100644
--- a/.github/copilot-tasks.md
+++ b/.github/copilot-tasks.md
@@ -67,10 +67,10 @@ Projekt vollstaendig umsetzen: aus PS_PW.xlsx und Stellenbeschreibungen.xlsx mon
 	- [x] Pflicht-Zielzellen vollstaendig konfiguriert
 
 ## Phase 6 - Ausgabeerzeugung
-- [ ] T11: Template-Verarbeitung bauen
-	- [ ] Template-Workbook laden
-	- [ ] Sheet pro aktiver Zuordnung klonen
-	- [ ] Inhalte assignment-spezifisch in Zielzellen schreiben
+- [x] T11: Template-Verarbeitung bauen
+	- [x] Template-Workbook laden
+	- [x] Sheet pro aktiver Zuordnung klonen
+	- [x] Inhalte assignment-spezifisch in Zielzellen schreiben
 - [ ] T12: Dateinamen und Speichern
 	- [ ] Muster: `Taetigkeitsnachweis_YYYY_MM_Vorname_Nachname.xlsx`
 	- [ ] Pro Mitarbeiter genau eine Datei pro Monat erzeugen
@@ -111,4 +111,4 @@ Projekt vollstaendig umsetzen: aus PS_PW.xlsx und Stellenbeschreibungen.xlsx mon
 8. T15 -> T16 -> T17
 
 ## Aktueller Startpunkt
-- [ ] Naechste aktive Aufgabe: T11 (Template-Verarbeitung bauen)
+- [ ] Naechste aktive Aufgabe: T12 (Dateinamen und Speichern)
diff --git a/src/taetigkeitsnachweis/writer.py b/src/taetigkeitsnachweis/writer.py
index d0b44b9..9a6e24b 100644
--- a/src/taetigkeitsnachweis/writer.py
+++ b/src/taetigkeitsnachweis/writer.py
@@ -1 +1,96 @@
 """Template-based output workbook writer."""
+
+from __future__ import annotations
+
+from collections import defaultdict
+from datetime import date
+from pathlib import Path
+from typing import Any
+
+from openpyxl import Workbook, load_workbook
+
+from .models import MatchedAssignment
+
+
+def _split_name_for_filename(name: str) -> tuple[str, str]:
+    cleaned = str(name or "").strip()
+    if "," in cleaned:
+        last_name, first_name = [part.strip() for part in cleaned.split(",", 1)]
+        return first_name or "Unknown", last_name or "Unknown"
+
+    parts = cleaned.split()
+    if len(parts) >= 2:
+        return parts[0], parts[-1]
+    if len(parts) == 1:
+        return parts[0], "Unknown"
+    return "Unknown", "Unknown"
+
+
+def _normalize_sheet_title(raw_title: str, fallback_index: int) -> str:
+    cleaned = (raw_title or "").strip().replace("[", "(").replace("]", ")")
+    if not cleaned:
+        cleaned = f"Assignment_{fallback_index}"
+    return cleaned[:31]
+
+
+def _set_target_value(worksheet: Any, target_cell: str, value: Any) -> None:
+    if not target_cell:
+        return
+    worksheet[target_cell] = value
+
+
+def build_employee_workbooks(
+    config: dict[str, Any],
+    matched_assignments: list[MatchedAssignment],
+    report_month: int,
+    report_year: int,
+    project_root: Path,
+) -> dict[str, Workbook]:
+    paths_cfg = config["paths"]
+    files_cfg = config["files"]
+    output_cfg = config["output"]
+    targets = config.get("template_targets", {})
+
+    template_path = (
+        project_root
+        / paths_cfg["template_dir"]
+        / files_cfg["template_workbook"]
+    )
+
+    assignments_by_employee: dict[str, list[MatchedAssignment]] = defaultdict(list)
+    for assignment in matched_assignments:
+        assignments_by_employee[assignment.allocation.employee_name].append(assignment)
+
+    workbooks: dict[str, Workbook] = {}
+    month_label = f"{report_month:02d}/{report_year}"
+    today_label = date.today().strftime("%d.%m.%Y")
+
+    for employee_name, assignments in assignments_by_employee.items():
+        workbook = load_workbook(template_path)
+        base_sheet = workbook.worksheets[0]
+
+        for index, assignment in enumerate(assignments, start=1):
+            if index == 1:
+                sheet = base_sheet
+            else:
+                sheet = workbook.copy_worksheet(base_sheet)
+
+            sheet_name_pattern = output_cfg.get("sheet_name_pattern", "{index}_{funktion}")
+            raw_sheet_name = sheet_name_pattern.format(
+                index=index,
+                funktion=assignment.masterdata.funktion,
+            )
+            sheet.title = _normalize_sheet_title(raw_sheet_name, index)
+
+            _set_target_value(sheet, targets.get("antragsnummer", ""), assignment.masterdata.antragsnummer)
+            _set_target_value(sheet, targets.get("name_vorname", ""), assignment.allocation.employee_name)
+            _set_target_value(sheet, targets.get("qualifikation", ""), assignment.masterdata.qualifikation)
+            _set_target_value(sheet, targets.get("funktion", ""), assignment.masterdata.funktion)
+            _set_target_value(sheet, targets.get("taetigkeiten", ""), assignment.masterdata.taetigkeit)
+            _set_target_value(sheet, targets.get("reporting_month_label", ""), month_label)
+            _set_target_value(sheet, targets.get("foerderquote", ""), f"{assignment.foerderquote_percent:.2f} %")
+            _set_target_value(sheet, targets.get("generated_on", ""), today_label)
+
+        workbooks[employee_name] = workbook
+
+    return workbooks