diff --git a/adminfront/src/features/tenants/routes/TenantUsersPage.tsx b/adminfront/src/features/tenants/routes/TenantUsersPage.tsx
index e2956a68..8850dcfc 100644
--- a/adminfront/src/features/tenants/routes/TenantUsersPage.tsx
+++ b/adminfront/src/features/tenants/routes/TenantUsersPage.tsx
@@ -23,20 +23,20 @@ function TenantUsersPage() {
   const params = useParams<{ tenantId: string }>();
   const tenantId = params.tenantId ?? "";
 
-  // 테넌트의 슬러그(companyCode)를 먼저 가져옴
+  // 테넌트의 슬러그(tenantSlug)를 먼저 가져옴
   const tenantQuery = useQuery({
     queryKey: ["tenant", tenantId],
     queryFn: () => fetchTenant(tenantId),
     enabled: tenantId.length > 0,
   });
 
-  const companyCode = tenantQuery.data?.slug;
+  const tenantSlug = tenantQuery.data?.slug;
 
   // 해당 슬러그로 사용자 검색
   const usersQuery = useQuery({
-    queryKey: ["users", { companyCode }],
-    queryFn: () => fetchUsers(100, 0, companyCode),
-    enabled: !!companyCode,
+    queryKey: ["users", { tenantSlug }],
+    queryFn: () => fetchUsers(100, 0, tenantSlug),
+    enabled: !!tenantSlug,
   });
 
   const users = usersQuery.data?.items ?? [];
diff --git a/adminfront/src/features/user-groups/routes/TenantUserGroupsTab.tsx b/adminfront/src/features/user-groups/routes/TenantUserGroupsTab.tsx
index d7f73e79..75f3602b 100644
--- a/adminfront/src/features/user-groups/routes/TenantUserGroupsTab.tsx
+++ b/adminfront/src/features/user-groups/routes/TenantUserGroupsTab.tsx
@@ -290,7 +290,7 @@ const MemberTable: React.FC<{
               {showTenant && (
                 <TableCell className="py-2">
                   <Badge variant="outline" className="text-[10px] h-5">
-                    {user.companyCode}
+                    {user.tenantSlug}
                   </Badge>
                 </TableCell>
               )}
@@ -360,7 +360,7 @@ const UserAddDialog: React.FC<{
       const res = await createUser({
         email,
         name,
-        companyCode: tenantSlug,
+        tenantSlug: tenantSlug,
         role: "user",
       });
       toast.success(
@@ -394,7 +394,7 @@ const UserAddDialog: React.FC<{
     if (!selectedUserId) return;
     setIsSubmitting(true);
     try {
-      await updateUser(selectedUserId, { companyCode: tenantSlug });
+      await updateUser(selectedUserId, { tenantSlug: tenantSlug });
       toast.success(
         t("msg.info.saved_success", "사용자가 테넌트에 배정되었습니다."),
       );
@@ -504,12 +504,12 @@ const UserAddDialog: React.FC<{
                             <div className="text-xs text-muted-foreground">
                               {user.email}
                             </div>
-                            {user.companyCode && (
+                            {user.tenantSlug && (
                               <Badge
                                 variant="outline"
                                 className="text-[10px] mt-1"
                               >
-                                {user.companyCode}
+                                {user.tenantSlug}
                               </Badge>
                             )}
                           </div>
diff --git a/adminfront/src/features/users/UserCreatePage.tsx b/adminfront/src/features/users/UserCreatePage.tsx
index d9018d2f..5e80926e 100644
--- a/adminfront/src/features/users/UserCreatePage.tsx
+++ b/adminfront/src/features/users/UserCreatePage.tsx
@@ -69,7 +69,7 @@ function UserCreatePage() {
       name: "",
       phone: "",
       role: "user",
-      companyCode: "",
+      tenantSlug: "",
       department: "",
       position: "",
       jobTitle: "",
@@ -80,13 +80,13 @@ function UserCreatePage() {
   // Lock company for tenant_admin
   React.useEffect(() => {
     const p = profile as any;
-    if (p?.role === "tenant_admin" && p.companyCode) {
-      setValue("companyCode", p.companyCode);
+    if (p?.role === "tenant_admin" && p.tenantSlug) {
+      setValue("tenantSlug", p.tenantSlug);
     }
   }, [profile, setValue]);
 
-  const selectedCompanyCode = watch("companyCode");
-  const selectedTenant = tenants.find((t) => t.slug === selectedCompanyCode);
+  const selectedTenantSlug = watch("tenantSlug");
+  const selectedTenant = tenants.find((t) => t.slug === selectedTenantSlug);
 
   const selectedTenantId = selectedTenant?.id ?? "";
 
@@ -353,15 +353,15 @@ function UserCreatePage() {
 
             <div className="grid gap-4 md:grid-cols-2">
               <div className="space-y-2">
-                <Label htmlFor="companyCode">
+                <Label htmlFor="tenantSlug">
                   {t("ui.admin.users.create.form.tenant", "테넌트 (Tenant)")}
                 </Label>
 
                 <div className="relative">
                   <select
-                    id="companyCode"
+                    id="tenantSlug"
                     className="flex h-9 w-full rounded-md border border-input bg-transparent px-3 py-1 text-sm shadow-sm transition-colors file:border-0 file:bg-transparent file:text-sm file:font-medium placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50"
-                    {...register("companyCode")}
+                    {...register("tenantSlug")}
                     disabled={(profile as any)?.role === "tenant_admin"}
                   >
                     <option value="">
diff --git a/adminfront/src/features/users/UserDetailPage.tsx b/adminfront/src/features/users/UserDetailPage.tsx
index 0c678c87..62655e2f 100644
--- a/adminfront/src/features/users/UserDetailPage.tsx
+++ b/adminfront/src/features/users/UserDetailPage.tsx
@@ -202,7 +202,7 @@ function UserDetailPage() {
       phone: "",
       role: "user",
       status: "active",
-      companyCode: "",
+      tenantSlug: "",
       department: "",
       position: "",
       jobTitle: "",
@@ -243,7 +243,7 @@ function UserDetailPage() {
         phone: user.phone || "",
         role: user.role,
         status: user.status,
-        companyCode: user.companyCode || "",
+        tenantSlug: user.tenantSlug || "",
         department: user.department || "",
         position: user.position || "",
         jobTitle: user.jobTitle || "",
@@ -377,7 +377,7 @@ function UserDetailPage() {
                     <div className="relative">
                       <select
                         className="flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-sm shadow-sm transition-colors focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-primary disabled:opacity-50"
-                        {...register("companyCode")}
+                        {...register("tenantSlug")}
                         disabled={
                           profile?.role === "tenant_admin" &&
                           userAffiliatedTenants.length <= 1
@@ -428,7 +428,7 @@ function UserDetailPage() {
                           to={`/tenants/${jt.id}`}
                           className={`inline-flex items-center gap-1 px-2 py-0.5 rounded border text-[11px] transition-colors ${
                             jt.id ===
-                            tenants.find((t) => t.slug === watch("companyCode"))
+                            tenants.find((t) => t.slug === watch("tenantSlug"))
                               ?.id
                               ? "bg-primary/10 border-primary/30 text-primary font-bold"
                               : "bg-background border-border text-muted-foreground hover:border-primary/50"
diff --git a/adminfront/src/features/users/UserListPage.tsx b/adminfront/src/features/users/UserListPage.tsx
index b4aa475c..dbc86498 100644
--- a/adminfront/src/features/users/UserListPage.tsx
+++ b/adminfront/src/features/users/UserListPage.tsx
@@ -88,8 +88,8 @@ function UserListPage() {
 
   // Lock company for tenant_admin
   React.useEffect(() => {
-    if (profile?.role === "tenant_admin" && profile.companyCode) {
-      setSelectedCompany(profile.companyCode);
+    if (profile?.role === "tenant_admin" && profile.tenantSlug) {
+      setSelectedCompany(profile.tenantSlug);
     }
   }, [profile]);
 
@@ -134,7 +134,7 @@ function UserListPage() {
   const query = useQuery({
     queryKey: [
       "users",
-      { limit, offset, search, companyCode: selectedCompany },
+      { limit, offset, search, tenantSlug: selectedCompany },
     ],
     queryFn: () => fetchUsers(limit, offset, search, selectedCompany),
     placeholderData: (previousData) => previousData,
@@ -531,7 +531,7 @@ function UserListPage() {
                       <TableCell>
                         <div className="flex flex-col text-sm">
                           <span className="font-medium text-blue-600">
-                            {user.tenant?.name || user.companyCode || "-"}
+                            {user.tenant?.name || user.tenantSlug || "-"}
                           </span>
                           <span className="text-xs text-muted-foreground">
                             {user.department || "-"}
diff --git a/adminfront/src/features/users/components/UserBulkMoveGroupModal.tsx b/adminfront/src/features/users/components/UserBulkMoveGroupModal.tsx
index 4334fe5c..c3f91f8b 100644
--- a/adminfront/src/features/users/components/UserBulkMoveGroupModal.tsx
+++ b/adminfront/src/features/users/components/UserBulkMoveGroupModal.tsx
@@ -138,7 +138,7 @@ export function UserBulkMoveGroupModal({
     if (!selectedTenantSlug) return;
     mutation.mutate({
       userIds,
-      companyCode: selectedTenantSlug,
+      tenantSlug: selectedTenantSlug,
       department: selectedGroupName, // can be empty for "No Department"
     } as any);
   };
diff --git a/adminfront/src/features/users/components/UserBulkUploadModal.tsx b/adminfront/src/features/users/components/UserBulkUploadModal.tsx
index 789b66b5..cf978162 100644
--- a/adminfront/src/features/users/components/UserBulkUploadModal.tsx
+++ b/adminfront/src/features/users/components/UserBulkUploadModal.tsx
@@ -74,7 +74,7 @@ export function UserBulkUploadModal({ onSuccess }: UserBulkUploadModalProps) {
   };
 
   const downloadTemplate = () => {
-    const headers = "email,name,phone,role,companyCode,department,employee_id";
+    const headers = "email,name,phone,role,tenant,department,employee_id";
     const example =
       "user1@example.com,홍길동,010-1234-5678,user,tenant-slug,개발팀,EMP001";
     const blob = new Blob(
@@ -203,7 +203,7 @@ ${example}`,
                       <tr key={u.email} className="border-t">
                         <td className="p-2">{u.email}</td>
                         <td className="p-2">{u.name}</td>
-                        <td className="p-2">{u.companyCode || "-"}</td>
+                        <td className="p-2">{u.tenantSlug || "-"}</td>
                       </tr>
                     ))}
                     {previewData.length > 10 && (
diff --git a/adminfront/src/features/users/utils/csvParser.test.ts b/adminfront/src/features/users/utils/csvParser.test.ts
index 019f0b83..f31bc396 100644
--- a/adminfront/src/features/users/utils/csvParser.test.ts
+++ b/adminfront/src/features/users/utils/csvParser.test.ts
@@ -3,7 +3,7 @@ import { parseUserCSV } from "./csvParser";
 
 describe("parseUserCSV", () => {
   it("should parse valid CSV correctly", () => {
-    const csv = `email,name,phone,role,companyCode,department,emp_id
+    const csv = `email,name,phone,role,tenant,department,emp_id
 user1@test.com,Hong Gil Dong,010-1111-2222,user,baron,HR,E001
 user2@test.com,Kim Cheol Su,,admin,baron,IT,E002`;
 
@@ -15,7 +15,7 @@ user2@test.com,Kim Cheol Su,,admin,baron,IT,E002`;
       name: "Hong Gil Dong",
       phone: "010-1111-2222",
       role: "user",
-      companyCode: "baron",
+      tenantSlug: "baron",
       department: "HR",
       metadata: {
         emp_id: "E001",
@@ -37,10 +37,10 @@ no-name@test.com,`;
   });
 
   it("should handle mixed case headers", () => {
-    const csv = `EMAIL,Name,CompanyCode
+    const csv = `EMAIL,Name,Tenant
 test@test.com,Test,baron`;
     const result = parseUserCSV(csv);
     expect(result[0].email).toBe("test@test.com");
-    expect(result[0].companyCode).toBe("baron");
+    expect(result[0].tenantSlug).toBe("baron");
   });
 });
diff --git a/adminfront/src/features/users/utils/csvParser.ts b/adminfront/src/features/users/utils/csvParser.ts
index f4ce6543..601eb762 100644
--- a/adminfront/src/features/users/utils/csvParser.ts
+++ b/adminfront/src/features/users/utils/csvParser.ts
@@ -30,8 +30,8 @@ export function parseUserCSV(text: string): BulkUserItem[] {
         item.phone = value;
       } else if (header === "role") {
         item.role = value;
-      } else if (header === "companycode") {
-        item.companyCode = value;
+      } else if (header === "tenant") {
+        item.tenantSlug = value;
       } else if (header === "department") {
         item.department = value;
       } else {
diff --git a/adminfront/src/lib/adminApi.ts b/adminfront/src/lib/adminApi.ts
index a390501c..fe885349 100644
--- a/adminfront/src/lib/adminApi.ts
+++ b/adminfront/src/lib/adminApi.ts
@@ -352,7 +352,7 @@ export type UserSummary = {
   phone?: string;
   role: string;
   status: string;
-  companyCode?: string;
+  tenantSlug?: string;
   tenant?: TenantSummary;
   joinedTenants?: TenantSummary[]; // [New] 다중 소속 테넌트 목록
   metadata?: Record<string, unknown>;
@@ -376,7 +376,7 @@ export type UserCreateRequest = {
   name: string;
   phone?: string;
   role?: string;
-  companyCode?: string;
+  tenantSlug?: string;
   department?: string;
   position?: string;
   jobTitle?: string;
@@ -392,7 +392,7 @@ export type UserUpdateRequest = {
   phone?: string;
   role?: string;
   status?: string;
-  companyCode?: string;
+  tenantSlug?: string;
   department?: string;
   position?: string;
   jobTitle?: string;
@@ -403,7 +403,7 @@ export type BulkUserItem = {
   name: string;
   phone?: string;
   role?: string;
-  companyCode?: string;
+  tenantSlug?: string;
   department?: string;
   metadata?: Record<string, unknown>;
 };
@@ -423,10 +423,10 @@ export async function fetchUsers(
   limit = 50,
   offset = 0,
   search?: string,
-  companyCode?: string,
+  tenantSlug?: string,
 ) {
   const { data } = await apiClient.get<UserListResponse>("/v1/admin/users", {
-    params: { limit, offset, search, companyCode },
+    params: { limit, offset, search, tenantSlug },
   });
   return data;
 }
@@ -446,10 +446,10 @@ export async function createUser(payload: UserCreateRequest) {
   return data;
 }
 
-export function exportUsersCSVUrl(search?: string, companyCode?: string) {
+export function exportUsersCSVUrl(search?: string, tenantSlug?: string) {
   const params = new URLSearchParams();
   if (search) params.append("search", search);
-  if (companyCode) params.append("companyCode", companyCode);
+  if (tenantSlug) params.append("tenantSlug", tenantSlug);
 
   // Get mock role from storage if exists for dev environment
   const mockRole = window.localStorage.getItem("X-Mock-Role");
@@ -503,7 +503,7 @@ export type UserProfileResponse = {
   role: string;
   department: string;
   affiliationType: string;
-  companyCode?: string;
+  tenantSlug?: string;
   tenantId?: string;
   metadata?: Record<string, unknown>;
   tenant?: TenantSummary;
diff --git a/adminfront/src/lib/i18n.test.ts b/adminfront/src/lib/i18n.test.ts
index cd5b5f0a..250e097f 100644
--- a/adminfront/src/lib/i18n.test.ts
+++ b/adminfront/src/lib/i18n.test.ts
@@ -8,15 +8,15 @@ describe("i18n utility", () => {
   });
 
   it("returns fallback if key not found", () => {
-    expect(t("non.existent.key", "Fallback")).toBe("Fallback");
+    expect(t("this.key.truly.does.not.exist", "Fallback")).toBe("Fallback");
   });
 
   it("returns key if fallback not provided and key not found", () => {
-    expect(t("non.existent.key")).toBe("non.existent.key");
+    expect(t("this.key.truly.does.not.exist")).toBe("this.key.truly.does.not.exist");
   });
 
   it("replaces variables in template", () => {
-    expect(t("test.key", "Hello {{ name }}", { name: "World" })).toBe(
+    expect(t("this.test.key", "Hello {{ name }}", { name: "World" })).toBe(
       "Hello World",
     );
   });
diff --git a/adminfront/tests/users_schema.spec.ts b/adminfront/tests/users_schema.spec.ts
index 88db0d7b..2450d7c8 100644
--- a/adminfront/tests/users_schema.spec.ts
+++ b/adminfront/tests/users_schema.spec.ts
@@ -70,7 +70,7 @@ test.describe("User Schema Dynamic Form", () => {
             id: "u-1",
             name: "John Doe",
             email: "john@test.com",
-            companyCode: "test-tenant",
+            tenantSlug: "test-tenant",
             tenant: { id: "t-1", name: "Test Tenant", slug: "test-tenant" },
             joinedTenants: [
               { id: "t-1", name: "Test Tenant", slug: "test-tenant" },