diff --git a/client-di2/src/pages/calculations.tsx b/client-di2/src/pages/calculations.tsx
index 3e1222e..85d393f 100644
--- a/client-di2/src/pages/calculations.tsx
+++ b/client-di2/src/pages/calculations.tsx
@@ -645,7 +645,8 @@ function VatTab({ data, quarters, balance, sync, markers }: { data: any; quarter
 
   const salesByRate = (data.byRate ?? []).filter((r: any) => r.direction === "sales");
   const purchasesByRate = (data.byRate ?? []).filter((r: any) => r.direction === "purchases");
-  const totals = data.totals ?? { accrued: 0, deducted: 0, toPay: 0 };
+  const totals = data.totals ?? { accrued: 0, deducted: 0 };
+  const quarter = data.currentQuarter ?? null;
   const redRows: any[] = markers?.rows ?? [];
   const markerCounts: any[] = markers?.byMarker ?? [];
 
@@ -661,6 +662,7 @@ function VatTab({ data, quarters, balance, sync, markers }: { data: any; quarter
               <span className="text-sm text-muted-foreground">Начислено</span>
             </div>
             <p className="text-xl font-bold text-foreground tabular-nums" data-testid="text-income-vat">{formatCurrency(totals.accrued)}</p>
+            <p className="text-xs text-muted-foreground mt-0.5">за период{data.dateFrom && data.dateTo ? ` ${data.dateFrom} — ${data.dateTo}` : ""}</p>
           </CardContent>
         </Card>
         <Card>
@@ -672,6 +674,7 @@ function VatTab({ data, quarters, balance, sync, markers }: { data: any; quarter
               <span className="text-sm text-muted-foreground">Вычет</span>
             </div>
             <p className="text-xl font-bold text-foreground tabular-nums" data-testid="text-expense-vat">{formatCurrency(totals.deducted)}</p>
+            <p className="text-xs text-muted-foreground mt-0.5">за период</p>
           </CardContent>
         </Card>
         <Card>
@@ -682,8 +685,11 @@ function VatTab({ data, quarters, balance, sync, markers }: { data: any; quarter
               </div>
               <span className="text-sm text-muted-foreground">К уплате</span>
             </div>
-            <p className={`text-xl font-bold tabular-nums ${totals.toPay >= 0 ? "text-destructive" : "text-success"}`} data-testid="text-vat-to-pay">
-              {formatCurrency(totals.toPay)}
+            <p className={`text-xl font-bold tabular-nums ${(quarter?.toPay ?? 0) >= 0 ? "text-destructive" : "text-success"}`} data-testid="text-vat-to-pay">
+              {formatCurrency(quarter?.toPay ?? 0)}
+            </p>
+            <p className="text-xs text-muted-foreground mt-0.5">
+              {quarter ? `квартал ${formatQuarterLabel(quarter.dateFrom)}` : ""}
             </p>
           </CardContent>
         </Card>
diff --git a/server/finance-di2/nds.routes.ts b/server/finance-di2/nds.routes.ts
index f9d9b94..9ed79c5 100644
--- a/server/finance-di2/nds.routes.ts
+++ b/server/finance-di2/nds.routes.ts
@@ -22,37 +22,69 @@ function strParam(v: unknown): string | null {
   return typeof v === "string" && v.trim() ? v.trim() : null;
 }
 
-// Границы периода: из query или текущий календарный квартал (НДС — квартальный налог)
-async function resolvePeriod(dateFrom: unknown, dateTo: unknown): Promise<{ from: string; to: string }> {
+// Границы периода: из query или вся история витрины (дефолт).
+// Отдельно возвращает границы квартала для KPI «К уплате»: квартал явного периода,
+// если он внутри одного квартала, иначе квартал последнего месяца в данных.
+async function resolvePeriod(dateFrom: unknown, dateTo: unknown): Promise<{ from: string; to: string; quarter: { from: string; to: string } }> {
   const fromParam = strParam(dateFrom);
   const toParam = strParam(dateTo);
-  if (fromParam && toParam) return { from: fromParam, to: toParam };
-  const bounds = await cachedQuery("nds:period-bounds", TTL_NDS, () =>
-    query(`SELECT date_trunc('quarter', CURRENT_DATE)::date AS qstart,
-                  (date_trunc('quarter', CURRENT_DATE) + interval '3 months' - interval '1 day')::date AS qend`)
+  const fmt = (d: unknown): string => (typeof d === "string" ? d : new Date(d as any).toISOString().slice(0, 10));
+  const bounds = await cachedQuery("nds:data-bounds", TTL_NDS, () =>
+    query(
+      `SELECT MIN(month)::date AS dfrom,
+              (date_trunc('quarter', MAX(month)) + interval '3 months' - interval '1 day')::date AS dto,
+              date_trunc('quarter', MAX(month))::date AS qfrom,
+              (date_trunc('quarter', MAX(month)) + interval '3 months' - interval '1 day')::date AS qto
+       FROM nds_monthly`
+    )
   );
   const row = bounds.rows[0] as any;
-  const fmt = (d: any) => (typeof d === "string" ? d : new Date(d).toISOString().slice(0, 10));
-  return { from: fromParam || fmt(row.qstart), to: toParam || fmt(row.qend) };
+  const quarter = { from: fmt(row.qfrom), to: fmt(row.qto) };
+  if (fromParam && toParam) {
+    const q = await cachedQuery(stableKey("nds:explicit-quarter", { fromParam, toParam }), TTL_NDS, () =>
+      query(
+        `SELECT date_trunc('quarter', $1::date)::date AS qfrom,
+                (date_trunc('quarter', $2::date) + interval '3 months' - interval '1 day')::date AS qto,
+                date_trunc('quarter', $1::date) = date_trunc('quarter', $2::date) AS same`,
+        [fromParam, toParam]
+      )
+    );
+    const qr = q.rows[0] as any;
+    if (qr.same) {
+      quarter.from = fmt(qr.qfrom);
+      quarter.to = fmt(qr.qto);
+    }
+  }
+  return { from: fromParam || fmt(row.dfrom), to: toParam || fmt(row.dto), quarter };
 }
 
 export function registerNdsRoutes(app: Express): void {
-  // Сводка за период: KPI, помесячная динамика с накопительным итогом внутри квартала,
-  // разрез по ставкам, структура начислений по типам операций, доля авансов
+  // Сводка за период: помесячная динамика с накопительным итогом внутри квартала,
+  // разрез по ставкам, структура начислений по типам операций, доля авансов.
+  // KPI: начислено/вычет — за период; «к уплате» — за квартал (currentQuarter), НДС не копится между кварталами.
   app.get("/api/di2/nds/summary", async (req, res) => {
     try {
-      const { from, to } = await resolvePeriod(req.query.dateFrom, req.query.dateTo);
+      const { from, to, quarter } = await resolvePeriod(req.query.dateFrom, req.query.dateTo);
       const params = [from, to];
+      const qParams = [quarter.from, quarter.to];
 
-      const [totals, monthly, byRate, events, advances] = await Promise.all([
+      const [totals, quarterTotals, monthly, byRate, events, advances] = await Promise.all([
         cachedQuery(stableKey("nds:summary:totals", req.query), TTL_NDS, () =>
+          query(
+            `SELECT COALESCE(SUM(vat) FILTER (WHERE direction = 'sales'), 0)::float8 AS accrued,
+                    COALESCE(SUM(vat) FILTER (WHERE direction = 'purchases'), 0)::float8 AS deducted
+             FROM nds_monthly WHERE month >= $1::date AND month <= $2::date`,
+            params
+          )
+        ),
+        cachedQuery(`nds:summary:quarter:${quarter.from}:${quarter.to}`, TTL_NDS, () =>
           query(
             `SELECT COALESCE(SUM(vat) FILTER (WHERE direction = 'sales'), 0)::float8 AS accrued,
                     COALESCE(SUM(vat) FILTER (WHERE direction = 'purchases'), 0)::float8 AS deducted,
                     (COALESCE(SUM(vat) FILTER (WHERE direction = 'sales'), 0)
                      - COALESCE(SUM(vat) FILTER (WHERE direction = 'purchases'), 0))::float8 AS "toPay"
              FROM nds_monthly WHERE month >= $1::date AND month <= $2::date`,
-            params
+            qParams
           )
         ),
         cachedQuery(stableKey("nds:summary:monthly", req.query), TTL_NDS, () =>
@@ -110,6 +142,7 @@ export function registerNdsRoutes(app: Express): void {
         dateFrom: from,
         dateTo: to,
         totals: totals.rows[0],
+        currentQuarter: { dateFrom: quarter.from, dateTo: quarter.to, ...quarterTotals.rows[0] },
         monthly: monthly.rows,
         byRate: byRate.rows,
         events: events.rows,