diff --git a/apps/web/src/app/features/client/lotes/lote-transfer.page.spec.ts b/apps/web/src/app/features/client/lotes/lote-transfer.page.spec.ts
index 6585532..bd87799 100644
--- a/apps/web/src/app/features/client/lotes/lote-transfer.page.spec.ts
+++ b/apps/web/src/app/features/client/lotes/lote-transfer.page.spec.ts
@@ -43,6 +43,7 @@ describe('LoteTransferPage', () => {
     await tick();
     // catálogos de la solicitud (campos de usuario de SAP) y series
     for (const alias of Object.keys(FIELDS)) ctrl.expectOne(`/api/sapdb/user-fields/OWTQ/${alias}`).flush(FIELDS[alias]);
+    ctrl.expectOne('/api/sl/SeriesService_GetDefaultSeries').flush({ Series: 7 });
     ctrl.expectOne('/api/sl/SeriesService_GetDocumentSeries').flush({ value: [{ Series: 7, Name: 'TR-01', Locked: 'tNO' }, { Series: 8, Name: 'OLD', Locked: 'tYES' }] });
     await tick();
   }
@@ -71,6 +72,12 @@ describe('LoteTransferPage', () => {
       expect(rowOf('302').textContent).toContain('Ya inmovilizado');
     });
 
+    it('deja elegida la serie por defecto de SAP', async () => {
+      await search('2090456');
+      expect(page().form().series).toBe(7);
+      expect((el().querySelector('sbo-select-field select') as HTMLSelectElement).selectedOptions[0]?.textContent?.trim()).toBe('TR-01');
+    });
+
     it('al marcar un almacén se precarga todo el stock y no se puede superar', async () => {
       await search('2090456');
       check('201');
@@ -109,7 +116,8 @@ describe('LoteTransferPage', () => {
           { ItemCode: 'A1', Quantity: 2, WarehouseCode: '302', FromWarehouseCode: '202', BatchNumbers: [{ BatchNumber: '2090456', Quantity: 2 }] },
         ],
       });
-      expect(req.request.body).not.toHaveProperty('Series');
+      // la serie por defecto de SAP viaja elegida
+      expect(req.request.body).toHaveProperty('Series', 7);
       req.flush({ DocEntry: 480, DocNum: 4123 });
       await tick();
       // vuelve a la búsqueda con el aviso de éxito
diff --git a/apps/web/src/app/features/client/lotes/lote-transfer.page.ts b/apps/web/src/app/features/client/lotes/lote-transfer.page.ts
index ab9bd84..313e4f2 100644
--- a/apps/web/src/app/features/client/lotes/lote-transfer.page.ts
+++ b/apps/web/src/app/features/client/lotes/lote-transfer.page.ts
@@ -177,7 +177,7 @@ export class LoteTransferPage {
       if (!rows.length) throw new Error(`No se encontró stock para el lote «${lot}»`);
       if (this.config.pickFrom && !rows.some((r) => r.WarehouseCode === this.fromWarehouse())) throw new Error(`El lote «${lot}» no tiene stock en el almacén ${this.fromWarehouse()}`);
       this.result.set({ lot, rows });
-      this.form.set(initialForm(this.config, todayIso()));
+      this.form.set(initialForm(this.config, todayIso(), this.defaultSeries.value() ?? null));
       this.message.set(null);
     } catch (e) {
       this.message.set({ kind: 'err', text: e instanceof Error && !('status' in e) ? e.message : apiErrorMessage(e) });
@@ -226,6 +226,8 @@ export class LoteTransferPage {
   protected readonly catalogs = resource({ loader: () => this.api.catalogs() });
   protected readonly options = computed(() => this.catalogs.value() ?? { movimientoInventario: [], tipoOperacion: [], tipoDespacho: [], movimientoAlmacen: [] });
   protected readonly series = resource({ loader: () => this.api.series().catch(() => []) });
+  /** La serie por defecto de SAP: queda elegida al buscar el lote (se puede cambiar o dejar en blanco). */
+  private readonly defaultSeries = resource({ loader: () => this.api.defaultSeries().catch(() => null) });
 
   protected readonly problems = computed(() => {
     const f = this.form();
diff --git a/apps/web/src/app/features/client/lotes/lotes-flujo-api.ts b/apps/web/src/app/features/client/lotes/lotes-flujo-api.ts
index 4544d09..47c21e5 100644
--- a/apps/web/src/app/features/client/lotes/lotes-flujo-api.ts
+++ b/apps/web/src/app/features/client/lotes/lotes-flujo-api.ts
@@ -70,6 +70,12 @@ export class LotesFlujoApi {
     return res.value.filter((r) => r['Locked'] !== 'tYES').map((r) => ({ value: Number(r['Series']), label: String(r['Name'] ?? r['Series']) }));
   }
 
+  /** La serie que SAP usa por defecto para las solicitudes de traslado, o `null` si no se pudo saber. */
+  async defaultSeries(): Promise<number | null> {
+    const res = await firstValueFrom(this.http.post<{ Series?: number }>(`${API_URL}/sl/SeriesService_GetDefaultSeries`, { DocumentTypeParams: { Document: OBJECT_TYPE } }));
+    return typeof res.Series === 'number' ? res.Series : null;
+  }
+
   create(body: Row): Promise<Row> {
     return this.master.create(RESOURCE, body);
   }
diff --git a/apps/web/src/app/features/client/lotes/lotes-flujo.spec.ts b/apps/web/src/app/features/client/lotes/lotes-flujo.spec.ts
index 6a2ca50..b974a02 100644
--- a/apps/web/src/app/features/client/lotes/lotes-flujo.spec.ts
+++ b/apps/web/src/app/features/client/lotes/lotes-flujo.spec.ts
@@ -49,6 +49,7 @@ describe('solicitud de inmovilización', () => {
   it('parte de los valores por defecto del flujo', () => {
     expect(initialForm(cfg, '2026-10-20')).toMatchObject({ toWarehouse: '302', movimientoAlmacen: '107', movimientoInventario: 'XTD', tipoOperacion: '11', tipoDespacho: 'N', series: null });
     expect(initialForm(LOT_FLOWS.liberar, '2026-10-20')).toMatchObject({ toWarehouse: '201', movimientoAlmacen: '108' });
+    expect(initialForm(cfg, '2026-10-20', 7).series).toBe(7);
   });
 
   it('pide motivo, comentario y acción, al menos un almacén y un destino distinto del origen', () => {
diff --git a/apps/web/src/app/features/client/lotes/lotes-flujo.ts b/apps/web/src/app/features/client/lotes/lotes-flujo.ts
index 6bec3fc..a38b5e3 100644
--- a/apps/web/src/app/features/client/lotes/lotes-flujo.ts
+++ b/apps/web/src/app/features/client/lotes/lotes-flujo.ts
@@ -77,10 +77,10 @@ export interface TransferForm {
   accion: string;
 }
 
-/** Valores iniciales de la solicitud de un flujo. */
-export const initialForm = (config: LotFlowConfig, today: string): TransferForm => ({
+/** Valores iniciales de la solicitud de un flujo (`series`: la que SAP usa por defecto, si se conoce). */
+export const initialForm = (config: LotFlowConfig, today: string, series: number | null = null): TransferForm => ({
   docDate: today,
-  series: null,
+  series,
   movimientoInventario: DEFAULT_MOVIMIENTO_INVENTARIO,
   tipoOperacion: DEFAULT_TIPO_OPERACION,
   tipoDespacho: DEFAULT_TIPO_DESPACHO,