diff --git a/apps/bff/src/integrations/whmcs/services/whmcs-client.service.ts b/apps/bff/src/integrations/whmcs/services/whmcs-client.service.ts
index 74b5fe80..072f5182 100644
--- a/apps/bff/src/integrations/whmcs/services/whmcs-client.service.ts
+++ b/apps/bff/src/integrations/whmcs/services/whmcs-client.service.ts
@@ -10,10 +10,7 @@ import type {
   WhmcsAddClientResponse,
   WhmcsValidateLoginResponse,
 } from "@customer-portal/domain/customer";
-import {
-  Providers as CustomerProviders,
-  type WhmcsClient,
-} from "@customer-portal/domain/customer";
+import { Providers as CustomerProviders, type WhmcsClient } from "@customer-portal/domain/customer";
 
 @Injectable()
 export class WhmcsClientService {
diff --git a/apps/bff/src/integrations/whmcs/services/whmcs-subscription.service.ts b/apps/bff/src/integrations/whmcs/services/whmcs-subscription.service.ts
index 06d660b0..4f69e441 100644
--- a/apps/bff/src/integrations/whmcs/services/whmcs-subscription.service.ts
+++ b/apps/bff/src/integrations/whmcs/services/whmcs-subscription.service.ts
@@ -85,7 +85,9 @@ export class WhmcsSubscriptionService {
       // Cache the result
       await this.cacheService.setSubscriptionsList(userId, result);
 
-      this.logger.log(`Fetched ${result.subscriptions.length} subscriptions for client ${clientId}`);
+      this.logger.log(
+        `Fetched ${result.subscriptions.length} subscriptions for client ${clientId}`
+      );
 
       // Apply status filter if needed
       if (filters.status) {
diff --git a/apps/bff/src/integrations/whmcs/whmcs.service.ts b/apps/bff/src/integrations/whmcs/whmcs.service.ts
index c7126b01..30cb89b6 100644
--- a/apps/bff/src/integrations/whmcs/whmcs.service.ts
+++ b/apps/bff/src/integrations/whmcs/whmcs.service.ts
@@ -2,7 +2,12 @@ import { Injectable, Inject } from "@nestjs/common";
 import type { Invoice, InvoiceList } from "@customer-portal/domain/billing";
 import type { Subscription, SubscriptionList } from "@customer-portal/domain/subscriptions";
 import type { PaymentMethodList, PaymentGatewayList } from "@customer-portal/domain/payments";
-import { Providers as CustomerProviders, type Address, type WhmcsClient } from "@customer-portal/domain/customer";
+import {
+  Providers as CustomerProviders,
+  addressSchema,
+  type Address,
+  type WhmcsClient,
+} from "@customer-portal/domain/customer";
 import { WhmcsConnectionOrchestratorService } from "./connection/services/whmcs-connection-orchestrator.service";
 import { WhmcsInvoiceService, InvoiceFilters } from "./services/whmcs-invoice.service";
 import {
@@ -150,7 +155,7 @@ export class WhmcsService {
    */
   async getClientAddress(clientId: number): Promise<Address> {
     const customer = await this.clientService.getClientDetails(clientId);
-    return (customer.address ?? {}) as Address;
+    return addressSchema.parse(customer.address ?? {});
   }
 
   async updateClientAddress(clientId: number, address: Partial<Address>): Promise<void> {
diff --git a/apps/bff/src/modules/orders/services/order-builder.service.ts b/apps/bff/src/modules/orders/services/order-builder.service.ts
index 04c7e60c..c7a5c8e4 100644
--- a/apps/bff/src/modules/orders/services/order-builder.service.ts
+++ b/apps/bff/src/modules/orders/services/order-builder.service.ts
@@ -118,15 +118,13 @@ export class OrderBuilder {
         | undefined;
       const addressChanged = !!orderAddress;
       const addressToUse = orderAddress || address;
-
       const address1 = typeof addressToUse?.address1 === "string" ? addressToUse.address1 : "";
       const address2 = typeof addressToUse?.address2 === "string" ? addressToUse.address2 : "";
       const fullStreet = [address1, address2].filter(Boolean).join(", ");
 
       orderFields.BillingStreet = fullStreet;
       orderFields.BillingCity = typeof addressToUse?.city === "string" ? addressToUse.city : "";
-      orderFields.BillingState =
-        typeof addressToUse?.state === "string" ? addressToUse.state : "";
+      orderFields.BillingState = typeof addressToUse?.state === "string" ? addressToUse.state : "";
       orderFields.BillingPostalCode =
         typeof addressToUse?.postcode === "string" ? addressToUse.postcode : "";
       orderFields.BillingCountry =
diff --git a/apps/portal/src/features/account/views/ProfileContainer.tsx b/apps/portal/src/features/account/views/ProfileContainer.tsx
index f2f893cb..389a87ae 100644
--- a/apps/portal/src/features/account/views/ProfileContainer.tsx
+++ b/apps/portal/src/features/account/views/ProfileContainer.tsx
@@ -178,9 +178,9 @@ export default function ProfileContainer() {
                 <h2 className="text-xl font-semibold text-gray-900">Personal Information</h2>
               </div>
               {!editingProfile && (
-                <Button 
-                  variant="outline" 
-                  size="sm" 
+                <Button
+                  variant="outline"
+                  size="sm"
                   onClick={() => setEditingProfile(true)}
                   leftIcon={<PencilIcon className="h-4 w-4" />}
                 >
@@ -296,9 +296,9 @@ export default function ProfileContainer() {
                 <h2 className="text-xl font-semibold text-gray-900">Address Information</h2>
               </div>
               {!editingAddress && (
-                <Button 
-                  variant="outline" 
-                  size="sm" 
+                <Button
+                  variant="outline"
+                  size="sm"
                   onClick={() => setEditingAddress(true)}
                   leftIcon={<PencilIcon className="h-4 w-4" />}
                 >
@@ -378,7 +378,9 @@ export default function ProfileContainer() {
                       {address.values.address1 && (
                         <p className="font-medium text-base">{address.values.address1}</p>
                       )}
-                      {address.values.address2 && <p className="text-gray-700">{address.values.address2}</p>}
+                      {address.values.address2 && (
+                        <p className="text-gray-700">{address.values.address2}</p>
+                      )}
                       <p className="text-gray-700">
                         {[address.values.city, address.values.state, address.values.postcode]
                           .filter(Boolean)
@@ -391,7 +393,7 @@ export default function ProfileContainer() {
                   <div className="text-center py-12">
                     <MapPinIcon className="h-12 w-12 text-gray-400 mx-auto mb-4" />
                     <p className="text-gray-600 mb-4">No address on file</p>
-                    <Button 
+                    <Button
                       onClick={() => setEditingAddress(true)}
                       leftIcon={<PencilIcon className="h-4 w-4" />}
                     >
diff --git a/apps/portal/src/features/auth/components/SignupForm/SignupForm.tsx b/apps/portal/src/features/auth/components/SignupForm/SignupForm.tsx
index 9587730e..45d17674 100644
--- a/apps/portal/src/features/auth/components/SignupForm/SignupForm.tsx
+++ b/apps/portal/src/features/auth/components/SignupForm/SignupForm.tsx
@@ -9,7 +9,11 @@ import { useState, useCallback, useMemo } from "react";
 import Link from "next/link";
 import { ErrorMessage } from "@/components/atoms";
 import { useSignup } from "../../hooks/use-auth";
-import { type SignupRequest, signupInputSchema } from "@customer-portal/domain/auth";
+import {
+  type SignupRequest,
+  signupInputSchema,
+  buildSignupRequest,
+} from "@customer-portal/domain/auth";
 import { useZodForm } from "@customer-portal/validation";
 import { z } from "zod";
 
@@ -84,17 +88,10 @@ export function SignupForm({
             })()
           : undefined;
 
-        // Remove confirmPassword and create SignupRequest
-        // The signup hook will handle API format transformation
-        const request: SignupRequest = {
+        const request: SignupRequest = buildSignupRequest({
           ...formData,
           ...(normalizedAddress ? { address: normalizedAddress } : {}),
-          // API expects both camelCase and snake_case (for WHMCS compatibility)
-          firstname: formData.firstName,
-          lastname: formData.lastName,
-          companyname: formData.company,
-          phonenumber: formData.phone,
-        };
+        });
         await signup(request);
         onSuccess?.();
       } catch (err) {
diff --git a/apps/portal/src/features/auth/hooks/use-auth.ts b/apps/portal/src/features/auth/hooks/use-auth.ts
index 624b4f03..cc1ff97b 100644
--- a/apps/portal/src/features/auth/hooks/use-auth.ts
+++ b/apps/portal/src/features/auth/hooks/use-auth.ts
@@ -187,9 +187,12 @@ export function useSession() {
       return undefined;
     }
 
-    const interval = setInterval(() => {
-      void refreshSession();
-    }, 5 * 60 * 1000); // Check every 5 minutes
+    const interval = setInterval(
+      () => {
+        void refreshSession();
+      },
+      5 * 60 * 1000
+    ); // Check every 5 minutes
 
     return () => clearInterval(interval);
   }, [isAuthenticated, refreshSession]);
diff --git a/apps/portal/src/features/auth/views/LoginView.tsx b/apps/portal/src/features/auth/views/LoginView.tsx
index afecf259..21d11170 100644
--- a/apps/portal/src/features/auth/views/LoginView.tsx
+++ b/apps/portal/src/features/auth/views/LoginView.tsx
@@ -18,10 +18,7 @@ import {
 export function LoginView() {
   const { loading, isAuthenticated } = useAuthStore();
   const searchParams = useSearchParams();
-  const reasonParam = useMemo(
-    () => searchParams?.get("reason"),
-    [searchParams]
-  );
+  const reasonParam = useMemo(() => searchParams?.get("reason"), [searchParams]);
   const [logoutReason, setLogoutReason] = useState<LogoutReason | null>(null);
   const [dismissed, setDismissed] = useState(false);
 
diff --git a/apps/portal/src/features/orders/components/OrderCard.tsx b/apps/portal/src/features/orders/components/OrderCard.tsx
index 5580d335..ad41bd98 100644
--- a/apps/portal/src/features/orders/components/OrderCard.tsx
+++ b/apps/portal/src/features/orders/components/OrderCard.tsx
@@ -118,7 +118,9 @@ export function OrderCard({ order, onClick, footer, className }: OrderCardProps)
       <div className="flex flex-col gap-4">
         <div className="flex flex-col gap-4 sm:flex-row sm:items-start sm:justify-between">
           <div className="flex min-w-0 flex-1 items-start gap-4">
-            <div className={cn("flex h-12 w-12 items-center justify-center rounded-xl", iconStyles)}>
+            <div
+              className={cn("flex h-12 w-12 items-center justify-center rounded-xl", iconStyles)}
+            >
               {serviceIcon}
             </div>
             <div className="min-w-0 space-y-2">
@@ -128,7 +130,9 @@ export function OrderCard({ order, onClick, footer, className }: OrderCardProps)
                   Order #{order.orderNumber || String(order.id).slice(-8)}
                 </span>
                 <span className="hidden text-gray-300 sm:inline">•</span>
-                <span>{formattedCreatedDate ? `Placed ${formattedCreatedDate}` : "Created date —"}</span>
+                <span>
+                  {formattedCreatedDate ? `Placed ${formattedCreatedDate}` : "Created date —"}
+                </span>
               </div>
               <p className="text-sm text-gray-600 line-clamp-2">{statusDescriptor.description}</p>
             </div>
diff --git a/apps/portal/src/features/orders/utils/order-presenters.ts b/apps/portal/src/features/orders/utils/order-presenters.ts
index 5437779f..34aedc5d 100644
--- a/apps/portal/src/features/orders/utils/order-presenters.ts
+++ b/apps/portal/src/features/orders/utils/order-presenters.ts
@@ -1,3 +1,7 @@
+import { normalizeBillingCycle } from "@customer-portal/domain/orders";
+
+export { normalizeBillingCycle } from "@customer-portal/domain/orders";
+
 export type OrderServiceCategory = "internet" | "sim" | "vpn" | "default";
 
 export type StatusTone = "success" | "info" | "warning" | "neutral";
@@ -128,12 +132,16 @@ export function calculateOrderTotals(
     for (const item of items) {
       const total = item.totalPrice ?? 0;
       const billingCycle = normalizeBillingCycle(item.billingCycle);
-      if (billingCycle === "monthly") {
-        monthlyTotal += total;
-      } else if (billingCycle === "onetime") {
-        oneTimeTotal += total;
-      } else {
-        monthlyTotal += total;
+      switch (billingCycle) {
+        case "monthly":
+          monthlyTotal += total;
+          break;
+        case "onetime":
+        case "free":
+          oneTimeTotal += total;
+          break;
+        default:
+          monthlyTotal += total;
       }
     }
   } else if (typeof fallbackTotal === "number") {
@@ -143,14 +151,6 @@ export function calculateOrderTotals(
   return { monthlyTotal, oneTimeTotal };
 }
 
-export function normalizeBillingCycle(value?: string): "monthly" | "onetime" | null {
-  if (!value) return null;
-  const normalized = value.trim().toLowerCase();
-  if (normalized === "monthly") return "monthly";
-  if (normalized === "onetime" || normalized === "one-time") return "onetime";
-  return null;
-}
-
 export function formatScheduledDate(scheduledAt?: string): string | undefined {
   if (!scheduledAt) return undefined;
   const date = new Date(scheduledAt);
diff --git a/apps/portal/src/features/orders/views/OrderDetail.tsx b/apps/portal/src/features/orders/views/OrderDetail.tsx
index 2c93f85b..8c5f9ad5 100644
--- a/apps/portal/src/features/orders/views/OrderDetail.tsx
+++ b/apps/portal/src/features/orders/views/OrderDetail.tsx
@@ -121,12 +121,9 @@ interface PresentedItem {
 }
 
 const determineItemType = (item: OrderItemSummary): ItemPresentationType => {
-  const candidates = [
-    item.itemClass,
-    item.status,
-    item.productName,
-    item.name,
-  ].map(value => value?.toLowerCase() ?? "");
+  const candidates = [item.itemClass, item.status, item.productName, item.name].map(
+    value => value?.toLowerCase() ?? ""
+  );
 
   if (candidates.some(value => value.includes("install"))) {
     return "installation";
@@ -379,9 +376,7 @@ export function OrderDetailContainer() {
                             </div>
                             <div className="min-w-0 space-y-2">
                               <div className="flex flex-wrap items-baseline gap-2">
-                                <p className="text-base font-semibold text-gray-900">
-                                  {item.name}
-                                </p>
+                                <p className="text-base font-semibold text-gray-900">{item.name}</p>
                                 {item.sku && (
                                   <span className="text-xs font-medium text-gray-400">
                                     SKU {item.sku}
diff --git a/apps/portal/src/features/orders/views/OrdersList.tsx b/apps/portal/src/features/orders/views/OrdersList.tsx
index 9feb6a4f..7d47d1ed 100644
--- a/apps/portal/src/features/orders/views/OrdersList.tsx
+++ b/apps/portal/src/features/orders/views/OrdersList.tsx
@@ -36,14 +36,7 @@ function OrdersSuccessBanner() {
 
 export function OrdersListContainer() {
   const router = useRouter();
-  const {
-    data: orders = [],
-    isLoading,
-    isError,
-    error,
-    refetch,
-    isFetching,
-  } = useOrdersList();
+  const { data: orders = [], isLoading, isError, error, refetch, isFetching } = useOrdersList();
 
   const { errorMessage, showRetry } = useMemo(() => {
     if (!isError) {
@@ -82,7 +75,7 @@ export function OrdersListContainer() {
             {showRetry && (
               <button
                 type="button"
-                onClick={() => refetch()}
+                onClick={() => void refetch()}
                 className="inline-flex items-center rounded-lg border border-blue-200 px-3 py-1.5 text-sm font-medium text-blue-700 transition hover:bg-blue-50 disabled:cursor-not-allowed disabled:opacity-60"
                 disabled={isFetching}
               >
diff --git a/apps/portal/src/features/subscriptions/components/SubscriptionTable/SubscriptionTable.tsx b/apps/portal/src/features/subscriptions/components/SubscriptionTable/SubscriptionTable.tsx
index 9c778361..63cc43fc 100644
--- a/apps/portal/src/features/subscriptions/components/SubscriptionTable/SubscriptionTable.tsx
+++ b/apps/portal/src/features/subscriptions/components/SubscriptionTable/SubscriptionTable.tsx
@@ -22,7 +22,6 @@ interface SubscriptionTableProps {
   subscriptions: Subscription[];
   loading?: boolean;
   onSubscriptionClick?: (subscription: Subscription) => void;
-  compact?: boolean;
   className?: string;
 }
 
@@ -89,7 +88,6 @@ export function SubscriptionTable({
   subscriptions,
   loading = false,
   onSubscriptionClick,
-  compact = false,
   className,
 }: SubscriptionTableProps) {
   const router = useRouter();
@@ -163,7 +161,7 @@ export function SubscriptionTable({
         ),
       },
     ];
-  }, [compact]);
+  }, []);
 
   const emptyState = {
     icon: <ServerIcon className="h-12 w-12" />,
@@ -240,5 +238,3 @@ export function SubscriptionTable({
 }
 
 export type { SubscriptionTableProps };
-
-
diff --git a/apps/portal/src/features/subscriptions/components/SubscriptionTable/index.ts b/apps/portal/src/features/subscriptions/components/SubscriptionTable/index.ts
index e0fba768..51cea480 100644
--- a/apps/portal/src/features/subscriptions/components/SubscriptionTable/index.ts
+++ b/apps/portal/src/features/subscriptions/components/SubscriptionTable/index.ts
@@ -1,3 +1,2 @@
-export { SubscriptionTable } from './SubscriptionTable';
-export type { SubscriptionTableProps } from './SubscriptionTable';
-
+export { SubscriptionTable } from "./SubscriptionTable";
+export type { SubscriptionTableProps } from "./SubscriptionTable";
diff --git a/apps/portal/src/features/subscriptions/views/SubscriptionDetail.tsx b/apps/portal/src/features/subscriptions/views/SubscriptionDetail.tsx
index 40f72673..6b5a28b2 100644
--- a/apps/portal/src/features/subscriptions/views/SubscriptionDetail.tsx
+++ b/apps/portal/src/features/subscriptions/views/SubscriptionDetail.tsx
@@ -185,7 +185,9 @@ export function SubscriptionDetailContainer() {
                 </h4>
                 <div className="flex items-center mt-2">
                   <CalendarIcon className="h-4 w-4 text-gray-400 mr-2" />
-                  <p className="text-lg font-medium text-gray-900">{formatDate(subscription.nextDue)}</p>
+                  <p className="text-lg font-medium text-gray-900">
+                    {formatDate(subscription.nextDue)}
+                  </p>
                 </div>
               </div>
               <div>
diff --git a/apps/portal/src/features/subscriptions/views/SubscriptionsList.tsx b/apps/portal/src/features/subscriptions/views/SubscriptionsList.tsx
index 778d8d6c..28c0cd8a 100644
--- a/apps/portal/src/features/subscriptions/views/SubscriptionsList.tsx
+++ b/apps/portal/src/features/subscriptions/views/SubscriptionsList.tsx
@@ -9,11 +9,7 @@ import { SearchFilterBar } from "@/components/molecules/SearchFilterBar/SearchFi
 import { LoadingTable } from "@/components/atoms/loading-skeleton";
 import { AsyncBlock } from "@/components/molecules/AsyncBlock/AsyncBlock";
 import { SubscriptionTable } from "@/features/subscriptions/components/SubscriptionTable";
-import {
-  ServerIcon,
-  CheckCircleIcon,
-  XCircleIcon,
-} from "@heroicons/react/24/outline";
+import { ServerIcon, CheckCircleIcon, XCircleIcon } from "@heroicons/react/24/outline";
 import { useSubscriptions, useSubscriptionStats } from "@/features/subscriptions/hooks";
 import type { Subscription } from "@customer-portal/domain/subscriptions";
 
diff --git a/packages/domain/auth/helpers.ts b/packages/domain/auth/helpers.ts
new file mode 100644
index 00000000..23cc0351
--- /dev/null
+++ b/packages/domain/auth/helpers.ts
@@ -0,0 +1,14 @@
+import type { z } from "zod";
+
+import { signupRequestSchema } from "./schema";
+
+type SignupRequestInput = z.input<typeof signupRequestSchema>;
+
+/**
+ * Convert signup form input into the canonical API payload.
+ * Reuses domain schema transformation to avoid frontend duplication.
+ */
+export function buildSignupRequest(input: SignupRequestInput) {
+  return signupRequestSchema.parse(input);
+}
+
diff --git a/packages/domain/auth/index.ts b/packages/domain/auth/index.ts
index 652b1cf8..734a7825 100644
--- a/packages/domain/auth/index.ts
+++ b/packages/domain/auth/index.ts
@@ -82,3 +82,5 @@ export {
   ssoLinkResponseSchema,
   checkPasswordNeededResponseSchema,
 } from "./schema";
+
+export { buildSignupRequest } from "./helpers";
diff --git a/packages/domain/customer/schema.ts b/packages/domain/customer/schema.ts
index 8ff6024c..711fef23 100644
--- a/packages/domain/customer/schema.ts
+++ b/packages/domain/customer/schema.ts
@@ -13,6 +13,7 @@
 import { z } from "zod";
 
 import { countryCodeSchema } from "../common/schema";
+import { whmcsClientSchema as whmcsRawClientSchema, whmcsCustomFieldSchema } from "./providers/whmcs/raw.types";
 
 // ============================================================================
 // Helper Schemas
@@ -166,16 +167,7 @@ const statsSchema = z.record(
   z.union([z.string(), z.number(), z.boolean()])
 ).optional();
 
-const whmcsRawCustomFieldSchema = z
-  .object({
-    id: numberLike.optional(),
-    value: z.string().optional().nullable(),
-    name: z.string().optional(),
-    type: z.string().optional(),
-  })
-  .passthrough();
-
-const whmcsRawCustomFieldsArraySchema = z.array(whmcsRawCustomFieldSchema);
+const whmcsRawCustomFieldsArraySchema = z.array(whmcsCustomFieldSchema);
 
 const whmcsCustomFieldsSchema = z
   .union([
@@ -184,7 +176,7 @@ const whmcsCustomFieldsSchema = z
     z
       .object({
         customfield: z
-          .union([whmcsRawCustomFieldSchema, whmcsRawCustomFieldsArraySchema])
+          .union([whmcsCustomFieldSchema, whmcsRawCustomFieldsArraySchema])
           .optional(),
       })
       .passthrough(),
@@ -214,54 +206,69 @@ const whmcsUsersSchema = z
  * - Preferences (email_preferences, allowSingleSignOn)
  * - Relations (users, stats, customfields)
  */
-export const whmcsClientSchema = z.object({
-  id: numberLike,
-  email: z.string(),
-  
-  // Profile (raw WHMCS field names)
-  firstname: z.string().nullable().optional(),
-  lastname: z.string().nullable().optional(),
-  fullname: z.string().nullable().optional(),
-  companyname: z.string().nullable().optional(),
-  phonenumber: z.string().nullable().optional(),
-  phonenumberformatted: z.string().nullable().optional(),
-  telephoneNumber: z.string().nullable().optional(),
-  
-  // Billing & Payment (raw WHMCS field names)
-  status: z.string().nullable().optional(),
-  language: z.string().nullable().optional(),
-  defaultgateway: z.string().nullable().optional(),
-  defaultpaymethodid: numberLike.nullable().optional(),
-  currency: numberLike.nullable().optional(),
-  currency_code: z.string().nullable().optional(), // snake_case from WHMCS
-  tax_id: z.string().nullable().optional(),
-  
-  // Preferences (raw WHMCS field names)
-  allowSingleSignOn: booleanLike.nullable().optional(),
-  email_verified: booleanLike.nullable().optional(), // snake_case from WHMCS
-  marketing_emails_opt_in: booleanLike.nullable().optional(), // snake_case from WHMCS
-  
-  // Metadata (raw WHMCS field names)
-  notes: z.string().nullable().optional(),
-  datecreated: z.string().nullable().optional(),
-  lastlogin: z.string().nullable().optional(),
-  
-  // Relations
-  address: addressSchema.nullable().optional(),
-  email_preferences: emailPreferencesSchema.nullable().optional(), // snake_case from WHMCS
-  customfields: whmcsCustomFieldsSchema,
-  users: whmcsUsersSchema,
-  stats: statsSchema.optional(),
-}).transform(data => ({
-  ...data,
-  // Normalize types only, keep field names as-is
-  id: typeof data.id === 'number' ? data.id : Number(data.id),
-  allowSingleSignOn: normalizeBoolean(data.allowSingleSignOn),
-  email_verified: normalizeBoolean(data.email_verified),
-  marketing_emails_opt_in: normalizeBoolean(data.marketing_emails_opt_in),
-  defaultpaymethodid: data.defaultpaymethodid ? Number(data.defaultpaymethodid) : null,
-  currency: data.currency ? Number(data.currency) : null,
-}));
+const nullableProfileFields = [
+  "firstname",
+  "lastname",
+  "fullname",
+  "companyname",
+  "phonenumber",
+  "phonenumberformatted",
+  "telephoneNumber",
+  "status",
+  "language",
+  "defaultgateway",
+  "currency_code",
+  "tax_id",
+  "notes",
+  "datecreated",
+  "lastlogin",
+] as const;
+
+type NullableProfileKey = (typeof nullableProfileFields)[number];
+
+const nullableProfileOverrides = nullableProfileFields.reduce<Record<string, z.ZodTypeAny>>(
+  (acc, field) => {
+    acc[field] = z.string().nullable().optional();
+    return acc;
+  },
+  {}
+);
+
+export const whmcsClientSchema = whmcsRawClientSchema
+  .extend({
+    ...nullableProfileOverrides,
+    // Allow nullable numeric strings
+    defaultpaymethodid: numberLike.nullable().optional(),
+    currency: numberLike.nullable().optional(),
+    allowSingleSignOn: booleanLike.nullable().optional(),
+    email_verified: booleanLike.nullable().optional(),
+    marketing_emails_opt_in: booleanLike.nullable().optional(),
+    address: addressSchema.nullable().optional(),
+    email_preferences: emailPreferencesSchema.nullable().optional(),
+    customfields: whmcsCustomFieldsSchema,
+    users: whmcsUsersSchema,
+    stats: statsSchema.optional(),
+  })
+  .transform(raw => {
+    const coerceNumber = (value: unknown) =>
+      value === null || value === undefined ? null : Number(value);
+
+    const coerceOptionalNumber = (value: unknown) =>
+      value === null || value === undefined ? undefined : Number(value);
+
+    return {
+      ...raw,
+      id: Number(raw.id),
+      client_id: coerceOptionalNumber((raw as Record<string, unknown>).client_id),
+      owner_user_id: coerceOptionalNumber((raw as Record<string, unknown>).owner_user_id),
+      userid: coerceOptionalNumber((raw as Record<string, unknown>).userid),
+      allowSingleSignOn: normalizeBoolean(raw.allowSingleSignOn),
+      email_verified: normalizeBoolean(raw.email_verified),
+      marketing_emails_opt_in: normalizeBoolean(raw.marketing_emails_opt_in),
+      defaultpaymethodid: coerceNumber(raw.defaultpaymethodid),
+      currency: coerceNumber(raw.currency),
+    };
+  });
 
 // ============================================================================
 // User Schema (API Response - Normalized camelCase)
diff --git a/packages/domain/orders/helpers.ts b/packages/domain/orders/helpers.ts
index 3a2b0d2e..ab30a2e6 100644
--- a/packages/domain/orders/helpers.ts
+++ b/packages/domain/orders/helpers.ts
@@ -5,6 +5,7 @@ import {
   type OrderSelections,
 } from "./schema";
 import type { SimConfigureFormData } from "../sim";
+import type { WhmcsOrderItem } from "./providers/whmcs/raw.types";
 
 export interface BuildSimOrderConfigurationsOptions {
   /**
@@ -26,6 +27,65 @@ const normalizeDate = (value: unknown): string | undefined => {
   return str.replace(/-/g, "");
 };
 
+type BillingCycle = WhmcsOrderItem["billingCycle"];
+
+const BILLING_CYCLE_ALIASES: Record<string, BillingCycle> = {
+  monthly: "monthly",
+  month: "monthly",
+  onetime: "onetime",
+  once: "onetime",
+  singlepayment: "onetime",
+  annual: "annually",
+  annually: "annually",
+  yearly: "annually",
+  year: "annually",
+  quarterly: "quarterly",
+  quarter: "quarterly",
+  qtr: "quarterly",
+  semiannual: "semiannually",
+  semiannually: "semiannually",
+  semiannualy: "semiannually",
+  semiannualpayment: "semiannually",
+  semiannualbilling: "semiannually",
+  biannual: "semiannually",
+  biannually: "semiannually",
+  biennial: "biennially",
+  biennially: "biennially",
+  triennial: "triennially",
+  triennially: "triennially",
+  free: "free",
+};
+
+const normalizeBillingCycleKey = (value: string): string =>
+  value.trim().toLowerCase().replace(/[\s_-]+/g, "");
+
+const DEFAULT_BILLING_CYCLE: BillingCycle = "monthly";
+
+export interface NormalizeBillingCycleOptions {
+  defaultValue?: BillingCycle;
+}
+
+/**
+ * Normalize arbitrary billing cycle strings to the canonical WHMCS values.
+ * Keeps mapping logic in the domain so both BFF and UI stay in sync.
+ */
+export function normalizeBillingCycle(
+  value: unknown,
+  options: NormalizeBillingCycleOptions = {}
+): BillingCycle {
+  if (typeof value !== "string") {
+    return options.defaultValue ?? DEFAULT_BILLING_CYCLE;
+  }
+
+  const directKey = normalizeBillingCycleKey(value);
+  const matched = BILLING_CYCLE_ALIASES[directKey];
+  if (matched) {
+    return matched;
+  }
+
+  return options.defaultValue ?? DEFAULT_BILLING_CYCLE;
+}
+
 /**
  * Build an OrderConfigurations object for SIM orders from the shared SimConfigureFormData.
  * Ensures the resulting payload conforms to the domain schema before it is sent to the BFF.
diff --git a/packages/domain/orders/index.ts b/packages/domain/orders/index.ts
index a030d18a..5c25a53c 100644
--- a/packages/domain/orders/index.ts
+++ b/packages/domain/orders/index.ts
@@ -42,6 +42,7 @@ export * from "./validation";
 export * from "./utils";
 export {
   buildSimOrderConfigurations,
+  normalizeBillingCycle,
   normalizeOrderSelections,
   type BuildSimOrderConfigurationsOptions,
 } from "./helpers";
diff --git a/packages/domain/orders/providers/salesforce/mapper.ts b/packages/domain/orders/providers/salesforce/mapper.ts
index f8ab535d..3bdf8e7e 100644
--- a/packages/domain/orders/providers/salesforce/mapper.ts
+++ b/packages/domain/orders/providers/salesforce/mapper.ts
@@ -10,6 +10,7 @@ import type {
   OrderItemSummary,
   OrderSummary,
 } from "../../contract";
+import { normalizeBillingCycle } from "../../helpers";
 import { orderDetailsSchema, orderSummarySchema, orderItemDetailsSchema } from "../../schema";
 import type {
   SalesforceOrderItemRecord,
@@ -26,7 +27,10 @@ export function transformSalesforceOrderItem(
   const pricebookEntry = record.PricebookEntry as Record<string, any> | null | undefined;
   const product = pricebookEntry?.Product2 as Record<string, any> | undefined;
   const productBillingCycle = product?.Billing_Cycle__c ?? undefined;
-  const billingCycle = record.Billing_Cycle__c ?? productBillingCycle ?? undefined;
+  const billingCycleRaw = record.Billing_Cycle__c ?? productBillingCycle ?? undefined;
+  const billingCycle = billingCycleRaw
+    ? normalizeBillingCycle(billingCycleRaw)
+    : undefined;
 
   const details = orderItemDetailsSchema.parse({
     id: record.Id,
diff --git a/packages/domain/orders/providers/whmcs/mapper.ts b/packages/domain/orders/providers/whmcs/mapper.ts
index 4157034a..1eb5b4f1 100644
--- a/packages/domain/orders/providers/whmcs/mapper.ts
+++ b/packages/domain/orders/providers/whmcs/mapper.ts
@@ -5,6 +5,7 @@
  */
 
 import type { OrderDetails, OrderItemDetails } from "../../contract";
+import { normalizeBillingCycle } from "../../helpers";
 import {
   type WhmcsOrderItem,
   type WhmcsAddOrderParams,
@@ -20,18 +21,6 @@ export interface OrderItemMappingResult {
   };
 }
 
-function normalizeBillingCycle(cycle: string | undefined): WhmcsOrderItem["billingCycle"] {
-  if (!cycle) return "monthly"; // Default
-  
-  const normalized = cycle.trim().toLowerCase();
-  if (normalized.includes("monthly")) return "monthly";
-  if (normalized.includes("one")) return "onetime";
-  if (normalized.includes("annual")) return "annually";
-  if (normalized.includes("quarter")) return "quarterly";
-  // Default to monthly if unrecognized
-  return "monthly";
-}
-
 /**
  * Map a single order item to WHMCS format
  */