diff --git a/src/__tests__/drafts-deferred-numbering.test.ts b/src/__tests__/drafts-deferred-numbering.test.ts
new file mode 100644
index 0000000..cb124e5
--- /dev/null
+++ b/src/__tests__/drafts-deferred-numbering.test.ts
@@ -0,0 +1,275 @@
+import { describe, it, expect, afterEach } from "vitest";
+import prisma from "../config/database";
+import {
+  previewIssuedOrderNumber,
+  previewInvoiceNumber,
+  previewOfferNumber,
+} from "../services/numbering.service";
+import {
+  createIssuedOrder,
+  updateIssuedOrder,
+  deleteIssuedOrder,
+} from "../services/issued-orders.service";
+import {
+  createInvoice,
+  updateInvoice,
+  deleteInvoice,
+} from "../services/invoices.service";
+import {
+  createOffer,
+  updateOffer,
+  deleteOffer,
+} from "../services/offers.service";
+
+// Track every row we create so the suite leaves the (real) app_test DB clean.
+const issuedOrderIds: number[] = [];
+const invoiceIds: number[] = [];
+const offerIds: number[] = [];
+
+afterEach(async () => {
+  for (const id of issuedOrderIds)
+    await prisma.issued_orders.deleteMany({ where: { id } });
+  for (const id of invoiceIds)
+    await prisma.invoices.deleteMany({ where: { id } });
+  for (const id of offerIds)
+    await prisma.quotations.deleteMany({ where: { id } });
+  issuedOrderIds.length = 0;
+  invoiceIds.length = 0;
+  offerIds.length = 0;
+  // Reset every sequence this suite may have touched so preview values are
+  // stable across tests and we don't leak consumed numbers into other files.
+  await prisma.number_sequences.deleteMany({
+    where: { type: { in: ["issued_order", "invoice", "offer"] } },
+  });
+});
+
+/* -------------------------------------------------------------------------- */
+/* Issued orders                                                              */
+/* -------------------------------------------------------------------------- */
+
+describe("issued-order drafts — deferred numbering", () => {
+  it("a draft has no number and does NOT consume the sequence", async () => {
+    const before = (await previewIssuedOrderNumber()).number;
+    const draft = await createIssuedOrder({}); // defaults to draft
+    issuedOrderIds.push(draft.id);
+    expect(draft.status).toBe("draft");
+    expect(draft.po_number).toBeNull();
+    // Preview is unchanged → the sequence was not consumed.
+    const after = (await previewIssuedOrderNumber()).number;
+    expect(after).toBe(before);
+  });
+
+  it("finalizing a draft (draft -> sent) assigns the next sequence number", async () => {
+    const expected = (await previewIssuedOrderNumber()).number;
+    const draft = await createIssuedOrder({});
+    issuedOrderIds.push(draft.id);
+
+    const res = await updateIssuedOrder(draft.id, { status: "sent" });
+    expect("error" in res).toBe(false);
+
+    const row = await prisma.issued_orders.findUnique({
+      where: { id: draft.id },
+    });
+    expect(row?.status).toBe("sent");
+    expect(row?.po_number).toBe(expected);
+    expect("po_number" in res && res.po_number).toBe(expected);
+  });
+
+  it("finalizing is idempotent — re-finalizing does not re-number", async () => {
+    const draft = await createIssuedOrder({});
+    issuedOrderIds.push(draft.id);
+
+    await updateIssuedOrder(draft.id, { status: "sent" });
+    const first = (
+      await prisma.issued_orders.findUnique({ where: { id: draft.id } })
+    )?.po_number;
+    const seqAfterFirst = await prisma.number_sequences.findFirst({
+      where: { type: "issued_order" },
+    });
+
+    // draft -> sent is no longer valid (already sent); the number must not change.
+    // Drive a second finalize-style update that keeps status sent.
+    await updateIssuedOrder(draft.id, { status: "sent" });
+    const second = (
+      await prisma.issued_orders.findUnique({ where: { id: draft.id } })
+    )?.po_number;
+    const seqAfterSecond = await prisma.number_sequences.findFirst({
+      where: { type: "issued_order" },
+    });
+
+    expect(second).toBe(first);
+    expect(seqAfterSecond?.last_number).toBe(seqAfterFirst?.last_number);
+  });
+
+  it("two drafts coexist with null numbers (no unique violation)", async () => {
+    const a = await createIssuedOrder({});
+    const b = await createIssuedOrder({});
+    issuedOrderIds.push(a.id, b.id);
+    expect(a.po_number).toBeNull();
+    expect(b.po_number).toBeNull();
+  });
+
+  it("deleting a draft releases nothing (no number was consumed)", async () => {
+    const before = (await previewIssuedOrderNumber()).number;
+    const draft = await createIssuedOrder({});
+    await deleteIssuedOrder(draft.id);
+    const after = (await previewIssuedOrderNumber()).number;
+    expect(after).toBe(before);
+  });
+});
+
+/* -------------------------------------------------------------------------- */
+/* Invoices                                                                   */
+/* -------------------------------------------------------------------------- */
+
+describe("invoice drafts — deferred numbering", () => {
+  it("a draft has no number and does NOT consume the sequence", async () => {
+    const before = (await previewInvoiceNumber()).number;
+    const draft = await createInvoice({});
+    invoiceIds.push(draft.id);
+    expect(draft.status).toBe("draft");
+    expect(draft.invoice_number).toBeNull();
+    const after = (await previewInvoiceNumber()).number;
+    expect(after).toBe(before);
+  });
+
+  it("finalizing a draft (draft -> issued) assigns the next sequence number", async () => {
+    const expected = (await previewInvoiceNumber()).number;
+    const draft = await createInvoice({});
+    invoiceIds.push(draft.id);
+
+    const res = await updateInvoice(draft.id, { status: "issued" });
+    expect("error" in res).toBe(false);
+
+    const row = await prisma.invoices.findUnique({ where: { id: draft.id } });
+    expect(row?.status).toBe("issued");
+    expect(row?.invoice_number).toBe(expected);
+    expect("invoice_number" in res && res.invoice_number).toBe(expected);
+  });
+
+  it("finalizing twice does not re-number / double-consume", async () => {
+    const draft = await createInvoice({});
+    invoiceIds.push(draft.id);
+
+    await updateInvoice(draft.id, { status: "issued" });
+    const first = (
+      await prisma.invoices.findUnique({ where: { id: draft.id } })
+    )?.invoice_number;
+    const seqAfterFirst = await prisma.number_sequences.findFirst({
+      where: { type: "invoice" },
+    });
+
+    // issued -> issued is a no-op status-wise; the number must stay put.
+    await updateInvoice(draft.id, { status: "issued" });
+    const second = (
+      await prisma.invoices.findUnique({ where: { id: draft.id } })
+    )?.invoice_number;
+    const seqAfterSecond = await prisma.number_sequences.findFirst({
+      where: { type: "invoice" },
+    });
+
+    expect(second).toBe(first);
+    expect(seqAfterSecond?.last_number).toBe(seqAfterFirst?.last_number);
+  });
+
+  it("two invoice drafts coexist with null numbers", async () => {
+    const a = await createInvoice({});
+    const b = await createInvoice({});
+    invoiceIds.push(a.id, b.id);
+    expect(a.invoice_number).toBeNull();
+    expect(b.invoice_number).toBeNull();
+  });
+
+  it("deleting a draft releases nothing", async () => {
+    const before = (await previewInvoiceNumber()).number;
+    const draft = await createInvoice({});
+    await deleteInvoice(draft.id);
+    const after = (await previewInvoiceNumber()).number;
+    expect(after).toBe(before);
+  });
+});
+
+/* -------------------------------------------------------------------------- */
+/* Offers                                                                     */
+/* -------------------------------------------------------------------------- */
+
+describe("offer drafts — deferred numbering", () => {
+  it("a draft has no number and does NOT consume the sequence", async () => {
+    const before = await previewOfferNumber();
+    const draft = await createOffer({});
+    if ("error" in draft) throw new Error(`createOffer failed: ${draft.error}`);
+    offerIds.push(draft.id);
+    expect(draft.status).toBe("draft");
+    expect(draft.quotation_number).toBeNull();
+    const after = await previewOfferNumber();
+    expect(after).toBe(before);
+  });
+
+  it("finalizing a draft (draft -> active) assigns the next sequence number", async () => {
+    const expected = await previewOfferNumber();
+    const draft = await createOffer({});
+    if ("error" in draft) throw new Error(`createOffer failed: ${draft.error}`);
+    offerIds.push(draft.id);
+
+    const res = await updateOffer(draft.id, { status: "active" });
+    expect("error" in res).toBe(false);
+
+    const row = await prisma.quotations.findUnique({ where: { id: draft.id } });
+    expect(row?.status).toBe("active");
+    expect(row?.quotation_number).toBe(expected);
+    expect("quotation_number" in res && res.quotation_number).toBe(expected);
+  });
+
+  it("finalizing twice does not re-number / double-consume", async () => {
+    const draft = await createOffer({});
+    if ("error" in draft) throw new Error(`createOffer failed: ${draft.error}`);
+    offerIds.push(draft.id);
+
+    await updateOffer(draft.id, { status: "active" });
+    const first = (
+      await prisma.quotations.findUnique({ where: { id: draft.id } })
+    )?.quotation_number;
+    const seqAfterFirst = await prisma.number_sequences.findFirst({
+      where: { type: "offer" },
+    });
+
+    // active -> active is a no-op; the number must stay put.
+    await updateOffer(draft.id, { status: "active" });
+    const second = (
+      await prisma.quotations.findUnique({ where: { id: draft.id } })
+    )?.quotation_number;
+    const seqAfterSecond = await prisma.number_sequences.findFirst({
+      where: { type: "offer" },
+    });
+
+    expect(second).toBe(first);
+    expect(seqAfterSecond?.last_number).toBe(seqAfterFirst?.last_number);
+  });
+
+  it("two offer drafts coexist with null numbers", async () => {
+    const a = await createOffer({});
+    const b = await createOffer({});
+    if ("error" in a) throw new Error(`createOffer failed: ${a.error}`);
+    if ("error" in b) throw new Error(`createOffer failed: ${b.error}`);
+    offerIds.push(a.id, b.id);
+    expect(a.quotation_number).toBeNull();
+    expect(b.quotation_number).toBeNull();
+  });
+
+  it("an offer created already-finalized (status active) numbers immediately", async () => {
+    const expected = await previewOfferNumber();
+    const offer = await createOffer({ status: "active" });
+    if ("error" in offer) throw new Error(`createOffer failed: ${offer.error}`);
+    offerIds.push(offer.id);
+    expect(offer.quotation_number).toBe(expected);
+  });
+
+  it("deleting a draft releases nothing", async () => {
+    const before = await previewOfferNumber();
+    const draft = await createOffer({});
+    if ("error" in draft) throw new Error(`createOffer failed: ${draft.error}`);
+    await deleteOffer(draft.id);
+    const after = await previewOfferNumber();
+    expect(after).toBe(before);
+  });
+});
diff --git a/src/__tests__/issued-orders.test.ts b/src/__tests__/issued-orders.test.ts
index ae99e26..becab93 100644
--- a/src/__tests__/issued-orders.test.ts
+++ b/src/__tests__/issued-orders.test.ts
@@ -120,7 +120,7 @@ describe("computeIssuedOrderTotals (NET + VAT-on-top)", () => {
 });
 
 describe("createIssuedOrder", () => {
-  it("assigns a PO number, defaults to draft, stores items", async () => {
+  it("defaults to draft with NO PO number, stores items", async () => {
     const c = await makeCustomer();
     const order = await createIssuedOrder({
       customer_id: c.id,
@@ -129,7 +129,8 @@ describe("createIssuedOrder", () => {
       ],
     });
     createdIds.push(order.id);
-    expect(order.po_number).toBeTruthy();
+    // Deferred numbering: a draft carries no number.
+    expect(order.po_number).toBeNull();
     expect(order.status).toBe("draft");
     const items = await prisma.issued_order_items.findMany({
       where: { issued_order_id: order.id },
@@ -137,6 +138,14 @@ describe("createIssuedOrder", () => {
     expect(items.length).toBe(1);
     expect(Number(items[0].unit_price)).toBe(100);
   });
+
+  it("numbers immediately when created already-finalized (status sent)", async () => {
+    const before = (await previewIssuedOrderNumber()).number;
+    const order = await createIssuedOrder({ status: "sent" });
+    createdIds.push(order.id);
+    expect(order.po_number).toBe(before);
+    expect(order.status).toBe("sent");
+  });
 });
 
 describe("updateIssuedOrder status transitions", () => {
@@ -183,7 +192,10 @@ describe("deleteIssuedOrder", () => {
     const order = await createIssuedOrder({
       items: [{ description: "X", quantity: 1, unit_price: 1 }],
     });
-    const before = order.po_number;
+    // Finalize so the order has a real (consumed) number to free on delete.
+    const finalized = await updateIssuedOrder(order.id, { status: "sent" });
+    const before = "po_number" in finalized ? finalized.po_number : null;
+    expect(before).toBeTruthy();
     await deleteIssuedOrder(order.id);
     expect(
       await prisma.issued_orders.findUnique({ where: { id: order.id } }),
diff --git a/src/schemas/invoices.schema.ts b/src/schemas/invoices.schema.ts
index e3fd6ad..e7d7cca 100644
--- a/src/schemas/invoices.schema.ts
+++ b/src/schemas/invoices.schema.ts
@@ -22,7 +22,7 @@ export const CreateInvoiceSchema = z.object({
   invoice_number: z.string().max(255).nullish(),
   order_id: nullableIntIdFromForm.nullish(),
   customer_id: nullableIntIdFromForm.nullish(),
-  status: z.string().max(20).optional().default("issued"),
+  status: z.string().max(20).optional().default("draft"),
   currency: z.string().max(20).optional().default("CZK"),
   vat_rate: numberInRange(0, 100).optional().default(21.0),
   apply_vat: booleanFromForm.optional().default(true),
diff --git a/src/schemas/offers.schema.ts b/src/schemas/offers.schema.ts
index e9d35ac..0bde5cc 100644
--- a/src/schemas/offers.schema.ts
+++ b/src/schemas/offers.schema.ts
@@ -36,9 +36,9 @@ export const CreateQuotationSchema = z.object({
   vat_rate: numberInRange(0, 100).optional().default(21.0),
   apply_vat: booleanFromForm.optional().default(true),
   status: z
-    .enum(["active", "ordered", "invalidated"])
+    .enum(["draft", "active", "ordered", "invalidated"])
     .optional()
-    .default("active"),
+    .default("draft"),
   scope_title: z.string().max(255).nullish(),
   scope_description: z.string().max(8000).nullish(),
   items: z.array(QuotationItemSchema).optional(),
@@ -54,7 +54,7 @@ export const UpdateQuotationSchema = z.object({
   language: z.string().max(20).optional(),
   vat_rate: numberInRange(0, 100).optional(),
   apply_vat: booleanFromForm.optional(),
-  status: z.enum(["active", "ordered", "invalidated"]).optional(),
+  status: z.enum(["draft", "active", "ordered", "invalidated"]).optional(),
   scope_title: z.string().max(255).nullish(),
   scope_description: z.string().max(8000).nullish(),
   items: z.array(QuotationItemSchema).optional(),
diff --git a/src/services/invoices.service.ts b/src/services/invoices.service.ts
index 4c586cc..704dc76 100644
--- a/src/services/invoices.service.ts
+++ b/src/services/invoices.service.ts
@@ -3,10 +3,13 @@ import { toCzk } from "./exchange-rates";
 import {
   generateInvoiceNumber,
   releaseInvoiceNumber,
+  assignInvoiceNumber,
 } from "./numbering.service";
 
-// Status transition rules matching PHP
+// Status transition rules matching PHP.
+// draft -> issued is the finalize step (consumes + assigns the invoice number).
 const VALID_TRANSITIONS: Record<string, string[]> = {
+  draft: ["issued"],
   issued: ["paid"],
   overdue: ["paid"],
   paid: [],
@@ -411,17 +414,26 @@ export async function getInvoice(id: number) {
 }
 
 export async function createInvoice(body: InvoiceInput) {
-  const invoiceNumber =
+  const status = body.status ? String(body.status) : "draft";
+
+  // Deferred numbering: a draft carries NO invoice_number (the column is
+  // nullable-unique so many drafts coexist). The official number is consumed
+  // only when the draft is finalized (assignInvoiceNumber on draft->issued).
+  // A caller-supplied number, or an invoice created already-finalized, numbers now.
+  const explicit =
     body.invoice_number !== undefined && body.invoice_number !== null
       ? String(body.invoice_number)
-      : (await generateInvoiceNumber()).number;
+      : null;
+  const invoiceNumber =
+    explicit ??
+    (status === "draft" ? null : (await generateInvoiceNumber()).number);
 
   const invoice = await prisma.invoices.create({
     data: {
       invoice_number: invoiceNumber,
       order_id: body.order_id ? Number(body.order_id) : null,
       customer_id: body.customer_id ? Number(body.customer_id) : null,
-      status: body.status ? String(body.status) : "issued",
+      status,
       currency: body.currency ? String(body.currency) : "CZK",
       vat_rate: body.vat_rate != null ? Number(body.vat_rate) : 21.0,
       apply_vat: body.apply_vat !== false,
@@ -479,9 +491,12 @@ export async function updateInvoice(id: number, body: InvoiceInput) {
 
   const data: Record<string, unknown> = { modified_at: new Date() };
 
-  // Allow full editing in 'issued' and 'overdue' states
-  const isDraft = currentStatus === "issued" || currentStatus === "overdue";
-  if (isDraft) {
+  // Allow full editing in 'draft', 'issued' and 'overdue' states.
+  const editable =
+    currentStatus === "draft" ||
+    currentStatus === "issued" ||
+    currentStatus === "overdue";
+  if (editable) {
     const strFields = [
       "currency",
       "payment_method",
@@ -515,8 +530,8 @@ export async function updateInvoice(id: number, body: InvoiceInput) {
       data.tax_date = body.tax_date ? new Date(String(body.tax_date)) : null;
   }
 
-  // Notes editable in issued/overdue
-  if (currentStatus === "issued" || currentStatus === "overdue") {
+  // Notes editable in draft/issued/overdue
+  if (editable) {
     if (body.notes !== undefined)
       data.notes = body.notes ? String(body.notes) : null;
     if (body.internal_notes !== undefined)
@@ -537,10 +552,27 @@ export async function updateInvoice(id: number, body: InvoiceInput) {
   if (body.paid_date !== undefined && currentStatus !== "paid")
     data.paid_date = body.paid_date ? new Date(String(body.paid_date)) : null;
 
-  await prisma.invoices.update({ where: { id }, data });
+  // Finalize transition draft -> issued: consume + write the official invoice
+  // number ATOMICALLY with the status change, so there is never a window where
+  // the invoice is "issued" but still has a null invoice_number.
+  // assignInvoiceNumber is idempotent (won't re-number an already-numbered row).
+  const finalizing =
+    currentStatus === "draft" &&
+    body.status !== undefined &&
+    String(body.status) === "issued";
 
-  // Only allow items update in draft state
-  if (isDraft && Array.isArray(body.items)) {
+  let assignedNumber: string | null = null;
+  if (finalizing) {
+    await prisma.$transaction(async (tx) => {
+      await tx.invoices.update({ where: { id }, data });
+      assignedNumber = await assignInvoiceNumber(id, tx);
+    });
+  } else {
+    await prisma.invoices.update({ where: { id }, data });
+  }
+
+  // Allow items update while editable (draft/issued/overdue).
+  if (editable && Array.isArray(body.items)) {
     await prisma.$transaction(async (tx) => {
       await tx.invoice_items.deleteMany({ where: { invoice_id: id } });
       await tx.invoice_items.createMany({
@@ -558,7 +590,12 @@ export async function updateInvoice(id: number, body: InvoiceInput) {
     });
   }
 
-  return { id, invoice_number: existing.invoice_number };
+  // Reflect the number the finalize transition just assigned (existing was read
+  // before the assign, so its invoice_number is still the pre-finalize null).
+  return {
+    id,
+    invoice_number: assignedNumber ?? existing.invoice_number,
+  };
 }
 
 export async function deleteInvoice(id: number) {
diff --git a/src/services/issued-orders.service.ts b/src/services/issued-orders.service.ts
index 040fa5b..4c3281f 100644
--- a/src/services/issued-orders.service.ts
+++ b/src/services/issued-orders.service.ts
@@ -4,6 +4,7 @@ import {
   generateIssuedOrderNumber,
   previewIssuedOrderNumber,
   releaseIssuedOrderNumber,
+  assignIssuedOrderNumber,
 } from "./numbering.service";
 
 export interface IssuedOrderItemInput {
@@ -185,20 +186,29 @@ export async function getIssuedOrder(id: number) {
 
 export async function createIssuedOrder(body: IssuedOrderInput) {
   return prisma.$transaction(async (tx) => {
-    const poNumber =
+    const status = body.status ? String(body.status) : "draft";
+
+    // Deferred numbering: a draft carries NO po_number (the column is
+    // nullable-unique so many drafts coexist). The official number is consumed
+    // only when the draft is finalized (assignIssuedOrderNumber on draft->sent).
+    // A caller-supplied number, or a doc created already-finalized, numbers now.
+    const explicit =
       body.po_number !== undefined &&
       body.po_number !== null &&
       body.po_number !== ""
         ? String(body.po_number)
-        : (await generateIssuedOrderNumber(undefined, tx)).number;
+        : null;
+    const poNumber =
+      explicit ??
+      (status === "draft"
+        ? null
+        : (await generateIssuedOrderNumber(undefined, tx)).number);
 
     const order = await tx.issued_orders.create({
       data: {
         po_number: poNumber,
         customer_id: body.customer_id ? Number(body.customer_id) : null,
-        status: (body.status
-          ? String(body.status)
-          : "draft") as $Enums.issued_orders_status,
+        status: status as $Enums.issued_orders_status,
         currency: body.currency ? String(body.currency) : "CZK",
         vat_rate: body.vat_rate != null ? Number(body.vat_rate) : 21.0,
         apply_vat: body.apply_vat !== false,
@@ -299,7 +309,23 @@ export async function updateIssuedOrder(id: number, body: IssuedOrderInput) {
 
   if (body.status !== undefined) data.status = String(body.status);
 
-  await prisma.issued_orders.update({ where: { id }, data });
+  // Finalize transition draft -> sent: consume + write the official number
+  // ATOMICALLY with the status change, so there is never a window where the
+  // order is "sent" but still has a null po_number. assignIssuedOrderNumber is
+  // idempotent (won't re-number an order that already has a number).
+  const finalizing =
+    currentStatus === "draft" &&
+    body.status !== undefined &&
+    String(body.status) === "sent";
+
+  if (finalizing) {
+    await prisma.$transaction(async (tx) => {
+      await tx.issued_orders.update({ where: { id }, data });
+      await assignIssuedOrderNumber(id, tx);
+    });
+  } else {
+    await prisma.issued_orders.update({ where: { id }, data });
+  }
 
   if (editable && Array.isArray(body.items)) {
     await prisma.$transaction(async (tx) => {
@@ -321,7 +347,18 @@ export async function updateIssuedOrder(id: number, body: IssuedOrderInput) {
     });
   }
 
-  return { id, po_number: existing.po_number };
+  // Reflect the number the finalize transition just assigned (existing was read
+  // before the assign, so its po_number is still the pre-finalize null).
+  const poNumber = finalizing
+    ? ((
+        await prisma.issued_orders.findUnique({
+          where: { id },
+          select: { po_number: true },
+        })
+      )?.po_number ?? existing.po_number)
+    : existing.po_number;
+
+  return { id, po_number: poNumber };
 }
 
 export async function deleteIssuedOrder(id: number) {
diff --git a/src/services/numbering.service.ts b/src/services/numbering.service.ts
index d050b33..efb2059 100644
--- a/src/services/numbering.service.ts
+++ b/src/services/numbering.service.ts
@@ -413,6 +413,76 @@ export async function previewIssuedOrderNumber(
   return { number, next_number: number };
 }
 
+/**
+ * Deferred-assign helpers — used when a draft (number-less) document is
+ * finalized. Each runs inside a transaction (the caller's `tx` if provided,
+ * otherwise a fresh `prisma.$transaction`), reads the row's current number, and:
+ *   - if it is already set (non-null/non-empty), returns it unchanged
+ *     (idempotent — finalizing twice never re-numbers / double-consumes); else
+ *   - calls the existing per-type generator (which consumes the sequence under
+ *     the same row lock) and writes the number onto the row.
+ * The sequence is consumed exactly once, atomically with the row write.
+ */
+export async function assignOfferNumber(
+  id: number,
+  tx?: TxClient,
+): Promise<string> {
+  const run = async (client: TxClient): Promise<string> => {
+    const row = await client.quotations.findUnique({
+      where: { id },
+      select: { quotation_number: true },
+    });
+    if (row?.quotation_number) return row.quotation_number;
+    const number = await generateOfferNumber(client);
+    await client.quotations.update({
+      where: { id },
+      data: { quotation_number: number },
+    });
+    return number;
+  };
+  return tx ? run(tx) : prisma.$transaction(run);
+}
+
+export async function assignInvoiceNumber(
+  id: number,
+  tx?: TxClient,
+): Promise<string> {
+  const run = async (client: TxClient): Promise<string> => {
+    const row = await client.invoices.findUnique({
+      where: { id },
+      select: { invoice_number: true },
+    });
+    if (row?.invoice_number) return row.invoice_number;
+    const { number } = await generateInvoiceNumber(undefined, client);
+    await client.invoices.update({
+      where: { id },
+      data: { invoice_number: number },
+    });
+    return number;
+  };
+  return tx ? run(tx) : prisma.$transaction(run);
+}
+
+export async function assignIssuedOrderNumber(
+  id: number,
+  tx?: TxClient,
+): Promise<string> {
+  const run = async (client: TxClient): Promise<string> => {
+    const row = await client.issued_orders.findUnique({
+      where: { id },
+      select: { po_number: true },
+    });
+    if (row?.po_number) return row.po_number;
+    const { number } = await generateIssuedOrderNumber(undefined, client);
+    await client.issued_orders.update({
+      where: { id },
+      data: { po_number: number },
+    });
+    return number;
+  };
+  return tx ? run(tx) : prisma.$transaction(run);
+}
+
 /** Release an issued-order number back to the pool (decrement if highest). */
 export async function releaseIssuedOrderNumber(
   year?: number,
diff --git a/src/services/offers.service.ts b/src/services/offers.service.ts
index ae78512..f81fa98 100644
--- a/src/services/offers.service.ts
+++ b/src/services/offers.service.ts
@@ -4,6 +4,7 @@ import {
   previewOfferNumber,
   releaseOfferNumber,
   isOfferNumberTaken,
+  assignOfferNumber,
 } from "./numbering.service";
 import { nasOffersManager } from "./nas-offers-manager";
 
@@ -162,20 +163,26 @@ export async function getOffer(id: number) {
 export async function createOffer(body: Record<string, any>) {
   try {
     return await prisma.$transaction(async (tx) => {
-      const quotationNumber =
+      const status = body.status ? String(body.status) : "draft";
+      const explicitNumber =
         body.quotation_number !== undefined && body.quotation_number !== null
           ? String(body.quotation_number)
-          : await generateOfferNumber(tx);
+          : null;
+
+      // Deferred numbering: a draft carries NO quotation_number (the column is
+      // nullable-unique so many drafts coexist). The official number is consumed
+      // only when the draft is finalized (assignOfferNumber on draft->active).
+      // A caller-supplied number, or an offer created already-finalized, numbers now.
+      const quotationNumber =
+        explicitNumber ??
+        (status === "draft" ? null : await generateOfferNumber(tx));
 
       // Re-check uniqueness INSIDE the transaction to close the TOCTOU window
       // between a pre-transaction check and the insert (mirrors createOrder).
       // generateOfferNumber already verifies its own generated numbers, so this
       // guards the caller-supplied path.
-      if (
-        body.quotation_number !== undefined &&
-        body.quotation_number !== null
-      ) {
-        const taken = await isOfferNumberTaken(quotationNumber);
+      if (explicitNumber !== null) {
+        const taken = await isOfferNumberTaken(explicitNumber);
         if (taken) {
           throw Object.assign(new Error("Číslo nabídky je již použito"), {
             status: 400,
@@ -198,7 +205,7 @@ export async function createOffer(body: Record<string, any>) {
           language: body.language ? String(body.language) : "cs",
           vat_rate: body.vat_rate != null ? Number(body.vat_rate) : 21.0,
           apply_vat: body.apply_vat !== false,
-          status: body.status ? String(body.status) : "active",
+          status,
           scope_title: body.scope_title ? String(body.scope_title) : null,
           scope_description: body.scope_description
             ? String(body.scope_description)
@@ -252,13 +259,25 @@ export async function updateOffer(id: number, body: Record<string, any>) {
   if (existing.status === "invalidated")
     return { error: "invalidated" as const };
 
+  // A finalized offer's number is immutable. A draft has no number yet
+  // (quotation_number === null) — it is assigned on finalize, not editable here,
+  // so an empty/absent submitted value on a draft is not a "change" and must not
+  // block the draft->active finalize.
   if (
+    existing.quotation_number !== null &&
     body.quotation_number !== undefined &&
     String(body.quotation_number) !== existing.quotation_number
   ) {
     return { error: "Číslo nabídky nelze změnit", status: 400 } as const;
   }
 
+  // Finalize transition draft -> active: assign the official number ATOMICALLY
+  // with the status change. assignOfferNumber is idempotent.
+  const finalizing =
+    existing.status === "draft" &&
+    body.status !== undefined &&
+    String(body.status) === "active";
+
   const data = {
     customer_id:
       body.customer_id !== undefined ? Number(body.customer_id) : undefined,
@@ -305,9 +324,11 @@ export async function updateOffer(id: number, body: Record<string, any>) {
     modified_at: new Date(),
   };
 
-  if (Array.isArray(body.items) || Array.isArray(body.sections)) {
+  let assignedNumber: string | null = null;
+  if (Array.isArray(body.items) || Array.isArray(body.sections) || finalizing) {
     await prisma.$transaction(async (tx) => {
       await tx.quotations.update({ where: { id }, data });
+      if (finalizing) assignedNumber = await assignOfferNumber(id, tx);
       if (Array.isArray(body.items)) {
         await tx.quotation_items.deleteMany({ where: { quotation_id: id } });
         await tx.quotation_items.createMany({
@@ -340,7 +361,12 @@ export async function updateOffer(id: number, body: Record<string, any>) {
     await prisma.quotations.update({ where: { id }, data });
   }
 
-  return { id, quotation_number: existing.quotation_number };
+  // Reflect the number the finalize transition just assigned (existing was read
+  // before the assign, so its quotation_number is still the pre-finalize null).
+  return {
+    id,
+    quotation_number: assignedNumber ?? existing.quotation_number,
+  };
 }
 
 export async function deleteOffer(id: number) {