diff --git a/src/modules/serialexecution.service.ts b/src/modules/serialexecution.service.ts
index 82a98ff..e7166b4 100644
--- a/src/modules/serialexecution.service.ts
+++ b/src/modules/serialexecution.service.ts
@@ -332,17 +332,33 @@ async function getFileTypeId(server: FastifyInstance,tenantId: number) {
 // --- Logik Helper (Unverändert zur Business Logik) ---
 
 function calculateDateRange(config: any, executionDate: dayjs.Dayjs) {
-    let firstDate = executionDate;
-    let lastDate = executionDate;
-    // Logik 1:1 übernommen
+    // Basis nehmen
+    let baseDate = executionDate;
+
+    let firstDate = baseDate;
+    let lastDate = baseDate;
+
     if (config.intervall === "monatlich" && config.dateDirection === "Rückwirkend") {
-        firstDate = executionDate.subtract(1, "month").date(1);
-        lastDate = executionDate.subtract(1, "month").endOf("month");
+        // 1. Monat abziehen
+        // 2. Start/Ende des Monats berechnen
+        // 3. WICHTIG: Zeit hart auf 12:00:00 setzen, damit Zeitzonen das Datum nicht kippen
+        firstDate = baseDate.subtract(1, "month").startOf("month").hour(12).minute(0).second(0).millisecond(0);
+        lastDate = baseDate.subtract(1, "month").endOf("month").hour(12).minute(0).second(0).millisecond(0);
+
     } else if (config.intervall === "vierteljährlich" && config.dateDirection === "Rückwirkend") {
-        firstDate = executionDate.subtract(1, "quarter").startOf("quarter");
-        lastDate = executionDate.subtract(1, "quarter").endOf("quarter");
+
+        firstDate = baseDate.subtract(1, "quarter").startOf("quarter").hour(12).minute(0).second(0).millisecond(0);
+        lastDate = baseDate.subtract(1, "quarter").endOf("quarter").hour(12).minute(0).second(0).millisecond(0);
     }
-    return { firstDate: firstDate.toISOString(), lastDate: lastDate.toISOString() };
+
+    // Das Ergebnis ist nun z.B.:
+    // firstDate: '2025-12-01T12:00:00.000Z' (Eindeutig der 1. Dezember)
+    // lastDate:  '2025-12-31T12:00:00.000Z' (Eindeutig der 31. Dezember)
+
+    return {
+        firstDate: firstDate.toISOString(),
+        lastDate: lastDate.toISOString()
+    };
 }
 
 async function getSaveData(item: any, tenant: any, firstDate: string, lastDate: string, executionDate: string, executedBy: string) {
@@ -453,7 +469,7 @@ function calculateDocumentTotals(rows: any[], taxType: string) {
     let titleSums: Record<string, number> = {};
 
     // Aktueller Titel für Gruppierung
-    let currentTitle = "Ohne Titel";
+    let currentTitle = "";
 
     rows.forEach(row => {
         if (row.mode === 'title') {
@@ -467,8 +483,8 @@ function calculateDocumentTotals(rows: any[], taxType: string) {
             totalNet += amount;
 
             // Summen pro Titel addieren
-            if (!titleSums[currentTitle]) titleSums[currentTitle] = 0;
-            titleSums[currentTitle] += amount;
+            //if (!titleSums[currentTitle]) titleSums[currentTitle] = 0;
+            if(currentTitle.length > 0) titleSums[currentTitle] += amount;
 
             // Steuer-Logik
             const tax = taxType === "19 UStG" || taxType === "13b UStG" ? 0 : Number(row.taxPercent);