diff --git a/llm_normalizer/backend/dist/services/addressQueryService.js b/llm_normalizer/backend/dist/services/addressQueryService.js
index c0848ac..db1b341 100644
--- a/llm_normalizer/backend/dist/services/addressQueryService.js
+++ b/llm_normalizer/backend/dist/services/addressQueryService.js
@@ -211,6 +211,22 @@ function deriveTaxQuarterWindowForDate(value) {
         period_to: `${year}-${String(quarterEndMonth).padStart(2, "0")}-${String(quarterEndDay).padStart(2, "0")}`
     };
 }
+function isFullCalendarMonthWindow(periodFrom, periodTo) {
+    const fromIso = normalizeIsoDateForQuery(periodFrom);
+    const toIso = normalizeIsoDateForQuery(periodTo);
+    if (!fromIso || !toIso) {
+        return false;
+    }
+    const fromMatch = fromIso.match(/^(\d{4})-(\d{2})-(\d{2})$/);
+    const toMatch = toIso.match(/^(\d{4})-(\d{2})-(\d{2})$/);
+    if (!fromMatch || !toMatch || fromMatch[1] !== toMatch[1] || fromMatch[2] !== toMatch[2] || fromMatch[3] !== "01") {
+        return false;
+    }
+    const year = Number(fromMatch[1]);
+    const month = Number(fromMatch[2]);
+    const lastDay = new Date(Date.UTC(year, month, 0)).getUTCDate();
+    return toMatch[3] === String(lastDay).padStart(2, "0");
+}
 function deriveMonthWindowForDate(value) {
     const isoDate = normalizeIsoDateForQuery(value);
     if (!isoDate) {
@@ -3003,8 +3019,12 @@ class AddressQueryService {
                 })
             });
         }
+        const vatTaxPeriodFromCarriedMonth = intent.intent === "vat_liability_confirmed_for_tax_period" &&
+            (filters.warnings.includes("period_from_from_followup_context") ||
+                filters.warnings.includes("period_to_from_followup_context")) &&
+            isFullCalendarMonthWindow(filters.extracted_filters.period_from, filters.extracted_filters.period_to);
         if (intent.intent === "vat_liability_confirmed_for_tax_period" &&
-            filters.warnings.includes("period_derived_from_month_phrase")) {
+            (filters.warnings.includes("period_derived_from_month_phrase") || vatTaxPeriodFromCarriedMonth)) {
             const taxQuarterWindow = deriveTaxQuarterWindowForDate(filters.extracted_filters.period_to);
             if (taxQuarterWindow) {
                 filters.extracted_filters = {
diff --git a/llm_normalizer/backend/src/services/addressQueryService.ts b/llm_normalizer/backend/src/services/addressQueryService.ts
index b49e6a4..43099eb 100644
--- a/llm_normalizer/backend/src/services/addressQueryService.ts
+++ b/llm_normalizer/backend/src/services/addressQueryService.ts
@@ -355,6 +355,23 @@ function deriveTaxQuarterWindowForDate(value: unknown): { period_from: string; p
   };
 }
 
+function isFullCalendarMonthWindow(periodFrom: unknown, periodTo: unknown): boolean {
+  const fromIso = normalizeIsoDateForQuery(periodFrom);
+  const toIso = normalizeIsoDateForQuery(periodTo);
+  if (!fromIso || !toIso) {
+    return false;
+  }
+  const fromMatch = fromIso.match(/^(\d{4})-(\d{2})-(\d{2})$/);
+  const toMatch = toIso.match(/^(\d{4})-(\d{2})-(\d{2})$/);
+  if (!fromMatch || !toMatch || fromMatch[1] !== toMatch[1] || fromMatch[2] !== toMatch[2] || fromMatch[3] !== "01") {
+    return false;
+  }
+  const year = Number(fromMatch[1]);
+  const month = Number(fromMatch[2]);
+  const lastDay = new Date(Date.UTC(year, month, 0)).getUTCDate();
+  return toMatch[3] === String(lastDay).padStart(2, "0");
+}
+
 function deriveMonthWindowForDate(value: unknown): { period_from: string; period_to: string } | null {
   const isoDate = normalizeIsoDateForQuery(value);
   if (!isoDate) {
@@ -3716,9 +3733,14 @@ export class AddressQueryService {
         })
       });
     }
+    const vatTaxPeriodFromCarriedMonth =
+      intent.intent === "vat_liability_confirmed_for_tax_period" &&
+      (filters.warnings.includes("period_from_from_followup_context") ||
+        filters.warnings.includes("period_to_from_followup_context")) &&
+      isFullCalendarMonthWindow(filters.extracted_filters.period_from, filters.extracted_filters.period_to);
     if (
       intent.intent === "vat_liability_confirmed_for_tax_period" &&
-      filters.warnings.includes("period_derived_from_month_phrase")
+      (filters.warnings.includes("period_derived_from_month_phrase") || vatTaxPeriodFromCarriedMonth)
     ) {
       const taxQuarterWindow = deriveTaxQuarterWindowForDate(filters.extracted_filters.period_to);
       if (taxQuarterWindow) {
diff --git a/llm_normalizer/backend/tests/addressQueryRuntimeM23.test.ts b/llm_normalizer/backend/tests/addressQueryRuntimeM23.test.ts
index a417c41..e5f0de0 100644
--- a/llm_normalizer/backend/tests/addressQueryRuntimeM23.test.ts
+++ b/llm_normalizer/backend/tests/addressQueryRuntimeM23.test.ts
@@ -4102,6 +4102,33 @@ describe("address query limited taxonomy and stage diagnostics", { timeout: 9000
     expect(result?.debug.route_expectation_status).toBe("matched");
   });
 
+  it("normalizes carried monthly debt period into VAT tax quarter for same-period follow-up", async () => {
+    const service = new AddressQueryService();
+    const result = await service.tryHandle("а какой ндс мы должны примерно заплатить за этот период?", {
+      followupContext: {
+        previous_intent: "receivables_confirmed_as_of_date",
+        previous_filters: {
+          organization: 'ООО "Альтернатива Плюс"',
+          period_from: "2017-05-01",
+          period_to: "2017-05-31",
+          as_of_date: "2017-05-31"
+        },
+        previous_anchor_type: "organization",
+        previous_anchor_value: 'ООО "Альтернатива Плюс"',
+        target_intent: "vat_liability_confirmed_for_tax_period"
+      }
+    });
+
+    expect(result?.handled).toBe(true);
+    expect(result?.debug.detected_intent).toBe("vat_liability_confirmed_for_tax_period");
+    expect(result?.debug.selected_recipe).toBe("address_vat_liability_confirmed_tax_period_v1");
+    expect(result?.debug.extracted_filters.period_from).toBe("2017-04-01");
+    expect(result?.debug.extracted_filters.period_to).toBe("2017-06-30");
+    expect(result?.debug.reasons).toContain("period_from_from_followup_context");
+    expect(result?.debug.reasons).toContain("period_derived_from_tax_quarter_for_confirmed_vat_liability");
+    expect(String(result?.reply_text ?? "")).toContain("01.04.2017..30.06.2017");
+  }, 35000);
+
   it("routes customer lifecycle question into dedicated aggregate recipe", async () => {
     const service = new AddressQueryService();
     const result = await service.tryHandle("Какие заказчики работали с нами в 2020 году?");