diff --git a/app/api/account/profile/route.ts b/app/api/account/profile/route.ts
index 5fba295..05d4b20 100644
--- a/app/api/account/profile/route.ts
+++ b/app/api/account/profile/route.ts
@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server";
 import { getSessionCustomer, updateCustomerProfile } from "../../../lib/customerAuth";
-import { normalizeVatId, isValidVatId } from "../../../lib/vatId";
+import { normalizeVatId, isValidVatId } from "@einfach-produktiv/invoicing";
 
 export async function GET() {
   const session = await getSessionCustomer();
diff --git a/app/api/checkout/route.ts b/app/api/checkout/route.ts
index 2ce1939..16fe40b 100644
--- a/app/api/checkout/route.ts
+++ b/app/api/checkout/route.ts
@@ -8,8 +8,8 @@ import { fetchProductsBySlug } from "../../lib/productsServer";
 import { describeBundleContents } from "../../lib/bundleContents";
 import { sendCriticalAlert } from "../../lib/alertAdmin";
 import { sendOrderConfirmationEmail } from "../../lib/orderEmail";
-import { normalizeVatId, isValidVatId } from "../../lib/vatId";
-import { checkVatIdViaVies } from "../../lib/vies";
+import { normalizeVatId, isValidVatId } from "@einfach-produktiv/invoicing";
+import { checkVatIdViaVies } from "@einfach-produktiv/invoicing/vies";
 import { computeExemptTotals, destinationCountry, isExemptionEligibleCountry } from "../../lib/vatExemption";
 import { upsertNewsletterContact } from "../../lib/brevo";
 import { paymentProvider, isPaymentTestMode } from "../../lib/payments";
diff --git a/app/api/checkout/validate-vat/route.ts b/app/api/checkout/validate-vat/route.ts
index e8e545c..ab02f16 100644
--- a/app/api/checkout/validate-vat/route.ts
+++ b/app/api/checkout/validate-vat/route.ts
@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server";
-import { normalizeVatId, isValidVatId } from "../../../lib/vatId";
-import { checkVatIdViaVies } from "../../../lib/vies";
+import { normalizeVatId, isValidVatId } from "@einfach-produktiv/invoicing";
+import { checkVatIdViaVies } from "@einfach-produktiv/invoicing/vies";
 
 // Called from CheckoutContent.tsx on the USt-IdNr. field's blur, whenever
 // the billing country is Österreich — the only cross-border-EU option this
diff --git a/app/checkout/components/CheckoutContent.tsx b/app/checkout/components/CheckoutContent.tsx
index 5f59742..f0be638 100644
--- a/app/checkout/components/CheckoutContent.tsx
+++ b/app/checkout/components/CheckoutContent.tsx
@@ -20,7 +20,7 @@ import { ORDER_KEY, PENDING_ORDER_KEY, type OrderSnapshot } from "../../lib/orde
 import { PaymentStep } from "./PaymentStep";
 import { dispatchAuthChanged } from "../../lib/auth";
 import { readCheckoutDraft, writeCheckoutDraft, clearCheckoutDraft } from "../../lib/checkoutDraft";
-import { normalizeVatId, isValidVatId } from "../../lib/vatId";
+import { normalizeVatId, isValidVatId, isValidPlz, plzInputPattern } from "@einfach-produktiv/invoicing";
 import { computeExemptTotals, destinationCountry, isExemptionEligibleCountry } from "../../lib/vatExemption";
 import { validateEmailFormat } from "../../lib/email";
 import type { ShippingMethod, ShippingCountry, PaymentMethod, TrustBadge, ShippingSettings } from "../../lib/payload";
@@ -37,8 +37,7 @@ import type { CustomerProfile } from "../../lib/customerAuth";
 // here. `?? 4` only matters if a country somehow isn't in the map at all
 // (shouldn't happen — the <select> options are built from the same list).
 function plzPattern(country: string, plzDigitsMap: Record<string, number>): string {
-  const digits = plzDigitsMap[country] ?? 4;
-  return `\\d{${digits}}`;
+  return plzInputPattern(plzDigitsMap[country] ?? 4);
 }
 
 // Same rules as the pattern/required attributes each field already
@@ -52,7 +51,7 @@ function validateRequired(label: string, value: string): string {
 function validateZip(value: string, country: string, plzDigitsMap: Record<string, number>): string {
   if (!value.trim()) return "PLZ ist erforderlich.";
   const digits = plzDigitsMap[country] ?? 4;
-  return new RegExp(`^\\d{${digits}}$`).test(value) ? "" : `PLZ muss aus ${digits} Ziffern bestehen.`;
+  return isValidPlz(value, digits) ? "" : `PLZ muss aus ${digits} Ziffern bestehen.`;
 }
 
 function validatePackstationNumber(value: string): string {
diff --git a/app/konto/bestellungen/[orderNumber]/page.tsx b/app/konto/bestellungen/[orderNumber]/page.tsx
index f35fa19..e3a9287 100644
--- a/app/konto/bestellungen/[orderNumber]/page.tsx
+++ b/app/konto/bestellungen/[orderNumber]/page.tsx
@@ -9,7 +9,7 @@ import { formatPrice, formatDate } from "../../../lib/format";
 import { getSessionCustomer, getCustomerOrderDetail, customerOrderAction } from "../../../lib/customerAuth";
 import { getProductImagesByIds, getPaymentMethods, groupPaymentMethodsForCheckout, getMediaUrlById } from "../../../lib/payload";
 import { computeTaxBreakdown } from "@einfach-produktiv/invoicing";
-import { buildTrackingUrl, CARRIER_LABELS } from "../../../lib/tracking";
+import { buildTrackingUrl, CARRIER_LABELS, type Carrier } from "@einfach-produktiv/invoicing";
 import { OrderActionButton } from "./components/OrderActionButton";
 import { SwitchPaymentButton } from "./components/SwitchPaymentButton";
 import { OrderStatusBadge } from "../../components/OrderStatusBadge";
@@ -92,7 +92,7 @@ export default async function KontoBestellungDetailPage({ params }: { params: Pr
 
           {order.trackingNumber && (
             <div className="flex flex-col gap-1 w-full">
-              <p className="text-label text-text-muted">Sendungsverfolgung{order.carrier ? ` (${CARRIER_LABELS[order.carrier] ?? order.carrier})` : ""}</p>
+              <p className="text-label text-text-muted">Sendungsverfolgung{order.carrier ? ` (${CARRIER_LABELS[order.carrier as Carrier] ?? order.carrier})` : ""}</p>
               {(() => {
                 const trackingUrl = buildTrackingUrl(order.carrier, order.trackingNumber);
                 return trackingUrl ? (
diff --git a/app/lib/shippingDhl.ts b/app/lib/shippingDhl.ts
index e8897f7..dc71080 100644
--- a/app/lib/shippingDhl.ts
+++ b/app/lib/shippingDhl.ts
@@ -1,6 +1,8 @@
 // Thin client for the backend's DHL custom endpoints (src/lib/endpoints/
 // dhlValidatePostNumber.ts, dhlAutocompleteAddress.ts) — own copy per repo,
-// same "no shared package yet" convention as app/lib/tracking.ts.
+// unlike vies.ts/vatId.ts/tracking.ts (now shared via @einfach-produktiv/invoicing),
+// since this proxies to Payload endpoints specific to this repo's own DHL wiring,
+// not portable logic.
 const PAYLOAD_URL = process.env.PAYLOAD_URL || "https://payload.mk360.de";
 const TENANT_SLUG = "einfach-produktiv";
 
diff --git a/app/lib/tracking.ts b/app/lib/tracking.ts
deleted file mode 100644
index 333fa39..0000000
--- a/app/lib/tracking.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-// Mirrors the Payload backend's own src/lib/tracking.ts — same carrier
-// set/labels/URL patterns, kept in sync by hand (two separate
-// deployments, no shared package). Used to render a clickable tracking
-// link on /konto/bestellungen/[orderNumber]; the backend's copy builds
-// the same link for the order-shipped email.
-export const CARRIER_LABELS: Record<string, string> = {
-  dhl: "DHL",
-  dpd: "DPD",
-  hermes: "Hermes",
-  ups: "UPS",
-  gls: "GLS",
-  other: "Sonstiger Versanddienstleister",
-};
-
-const CARRIER_TRACKING_URL: Record<string, (trackingNumber: string) => string> = {
-  dhl: (n) => `https://www.dhl.de/de/privatkunden/dhl-sendungsverfolgung.html?piececode=${encodeURIComponent(n)}`,
-  dpd: (n) => `https://tracking.dpd.de/status/de_DE/parcel/${encodeURIComponent(n)}`,
-  hermes: (n) => `https://www.myhermes.de/empfangen/sendungsverfolgung/sendungsinformation/#${encodeURIComponent(n)}`,
-  ups: (n) => `https://www.ups.com/track?loc=de_DE&tracknum=${encodeURIComponent(n)}`,
-  gls: (n) => `https://www.gls-pakete.de/sendungsverfolgung?trackingNumber=${encodeURIComponent(n)}`,
-};
-
-export function buildTrackingUrl(carrier: string | null | undefined, trackingNumber: string | null | undefined): string | null {
-  if (!carrier || !trackingNumber) return null;
-  return CARRIER_TRACKING_URL[carrier]?.(trackingNumber) ?? null;
-}
diff --git a/app/lib/vatId.ts b/app/lib/vatId.ts
deleted file mode 100644
index 35ea3da..0000000
--- a/app/lib/vatId.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-// Mirrors the backend's own USt-IdNr. validation exactly (Orders.ts/
-// Customers.ts/CompanySettings.ts in the Payload repo) — kept as a plain
-// client+server-safe helper here since this repo's frontend needs the same
-// check twice (checkout's instant client-side pattern + api/checkout's own
-// server-side re-validation, same "never trust the client" reasoning as
-// every other checkout field).
-const VAT_ID_PATTERN = /^[A-Z]{2}[A-Z0-9]{2,12}$/;
-
-export function normalizeVatId(value: string): string {
-  return value.toUpperCase().trim();
-}
-
-export function isValidVatId(value: string): boolean {
-  return VAT_ID_PATTERN.test(value);
-}
diff --git a/app/lib/vies.ts b/app/lib/vies.ts
deleted file mode 100644
index fa319b4..0000000
--- a/app/lib/vies.ts
+++ /dev/null
@@ -1,58 +0,0 @@
-// Server-only — calls the European Commission's public VIES REST API to
-// confirm an EU VAT ID is actually registered, not just correctly
-// formatted (see lib/vatId.ts's own comment: format alone is never
-// enough to zero-rate an invoice). Confirmed live and working against
-// the real endpoint 2026-07-23 (POST {countryCode, vatNumber} →
-// {valid: boolean, ...}) — this is the Commission's own documented REST
-// API, not a guess.
-const VIES_URL = "https://ec.europa.eu/taxation_customs/vies/rest-api/check-vat-number";
-
-export type ViesCheckResult =
-  | { ok: true; valid: boolean; name: string | null; address: string | null }
-  | { ok: false; reason: string };
-
-// `vatNumber` must NOT include the country prefix (VIES wants it split
-// out) — callers pass the full "DE123456789"-shaped id and this function
-// does the splitting, since every call site already has the normalized
-// full id (see lib/vatId.ts's normalizeVatId()) rather than the two parts
-// separately.
-export async function checkVatIdViaVies(vatId: string): Promise<ViesCheckResult> {
-  const countryCode = vatId.slice(0, 2);
-  const vatNumber = vatId.slice(2);
-  if (!countryCode || !vatNumber) return { ok: false, reason: "Ungültiges USt-IdNr.-Format." };
-
-  try {
-    // 8s timeout — VIES is a shared EU-wide government service with no
-    // uptime SLA to this shop; a slow/unreachable response must not hang
-    // checkout indefinitely. Callers treat `ok: false` as "couldn't
-    // confirm" and fail closed (no exemption), never as "confirmed invalid".
-    const res = await fetch(VIES_URL, {
-      method: "POST",
-      headers: { "Content-Type": "application/json" },
-      body: JSON.stringify({ countryCode, vatNumber }),
-      signal: AbortSignal.timeout(8000),
-    });
-    if (!res.ok) return { ok: false, reason: `VIES antwortete mit ${res.status}` };
-    const data: { actionSucceed?: boolean; valid?: boolean; name?: string; address?: string; errorWrappers?: { error?: string }[] } = await res.json();
-    // VIES answers 200 even when it couldn't actually perform the check —
-    // `actionSucceed: false` (e.g. `MS_UNAVAILABLE`, the member state's own
-    // national gateway being temporarily down — Germany's in particular is
-    // known to do this) means "couldn't confirm", not "confirmed invalid".
-    // Without this check a `MS_UNAVAILABLE` response fell through to
-    // `Boolean(data.valid)` on a body that has no `valid` field at all,
-    // silently reading as `valid: false` — a real, currently-registered VAT
-    // ID would then look rejected instead of "VIES unavailable, try again".
-    if (data.actionSucceed === false) {
-      const reason = data.errorWrappers?.[0]?.error ?? "VIES konnte die Anfrage nicht bearbeiten.";
-      return { ok: false, reason: `VIES: ${reason}` };
-    }
-    return {
-      ok: true,
-      valid: Boolean(data.valid),
-      name: data.name && data.name !== "---" ? data.name : null,
-      address: data.address && data.address !== "---" ? data.address : null,
-    };
-  } catch (err) {
-    return { ok: false, reason: err instanceof Error ? err.message : "VIES ist gerade nicht erreichbar." };
-  }
-}
diff --git a/package-lock.json b/package-lock.json
index 197311d..7088095 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -455,8 +455,8 @@
       }
     },
     "node_modules/@einfach-produktiv/invoicing": {
-      "version": "0.2.9",
-      "resolved": "git+https://git.mk360.de/Marco/einfach-produktiv-invoicing.git#87cf1db330e6a415fbcd31b83c6c4470a73b07a9",
+      "version": "0.3.0",
+      "resolved": "git+https://git.mk360.de/Marco/einfach-produktiv-invoicing.git#2b4b2eb91fa78d2a5e7e9e0fdb87f9947e32c41f",
       "dependencies": {
         "@e-invoice-eu/core": "^3.1.1"
       },