diff --git a/app/Console/Commands/InitLookup.php b/app/Console/Commands/InitLookup.php
index aa52ec4f4a35..f37de078be2f 100644
--- a/app/Console/Commands/InitLookup.php
+++ b/app/Console/Commands/InitLookup.php
@@ -21,7 +21,7 @@ class InitLookup extends Command
      *
      * @var string
      */
-    protected $signature = 'ninja:init-lookup {--truncate=} {--validate=} {--update=} {--company_id=} {--page_size=100} {--database=db-ninja-1}';
+    protected $signature = 'ninja:init-lookup {--truncate=} {--subdomain} {--validate=} {--update=} {--company_id=} {--page_size=100} {--database=db-ninja-1}';
 
     /**
      * The console command description.
@@ -57,9 +57,12 @@ class InitLookup extends Command
         $database = $this->option('database');
         $dbServer = DbServer::whereName($database)->first();
 
-        if ($this->option('truncate')) {
+        if ($this->option('subdomain')) {
+            $this->logMessage('Updating subdomains...');
+            $this->popuplateSubdomains();
+        } else if ($this->option('truncate')) {
+            $this->logMessage('Truncating data...');
             $this->truncateTables();
-            $this->logMessage('Truncated');
         } else {
             config(['database.default' => $this->option('database')]);
 
@@ -87,6 +90,30 @@ class InitLookup extends Command
         }
     }
 
+    private function popuplateSubdomains()
+    {
+        $data = [];
+
+        config(['database.default' => $this->option('database')]);
+
+        $accounts = DB::table('accounts')
+                        ->orderBy('id')
+                        ->where('subdomain', '!=', '')
+                        ->get(['account_key', 'subdomain']);
+        foreach ($accounts as $account) {
+            $data[$account->account_key] = $account->subdomain;
+        }
+
+        config(['database.default' => DB_NINJA_LOOKUP]);
+
+        $validate = $this->option('validate');
+        $update = $this->option('update');
+
+        foreach ($data as $accountKey => $subdomain) {
+            LookupAccount::whereAccountKey($accountKey)->update(['subdomain' => $subdomain]);
+        }
+    }
+
     private function initCompanies($dbServerId, $offset = 0)
     {
         $data = [];
@@ -340,6 +367,7 @@ class InitLookup extends Command
     protected function getOptions()
     {
         return [
+            ['subdomain', null, InputOption::VALUE_OPTIONAL, 'Subdomain', null],
             ['truncate', null, InputOption::VALUE_OPTIONAL, 'Truncate', null],
             ['company_id', null, InputOption::VALUE_OPTIONAL, 'Company Id', null],
             ['page_size', null, InputOption::VALUE_OPTIONAL, 'Page Size', null],
diff --git a/app/Http/Controllers/AccountController.php b/app/Http/Controllers/AccountController.php
index f41b9e4cadf3..64b553e58732 100644
--- a/app/Http/Controllers/AccountController.php
+++ b/app/Http/Controllers/AccountController.php
@@ -769,11 +769,20 @@ class AccountController extends BaseController
      */
     public function saveClientPortalSettings(SaveClientPortalSettings $request)
     {
-
         $account = $request->user()->account;
 
-        if($account->subdomain !== $request->subdomain)
+        // check subdomain is unique in the lookup tables
+        if (request()->subdomain) {
+            if (! \App\Models\LookupAccount::validateField('subdomain', request()->subdomain, $account)) {
+                return Redirect::to('settings/' . ACCOUNT_CLIENT_PORTAL)
+                    ->withError(trans('texts.subdomain_taken'))
+                    ->withInput();
+            }
+        }
+
+        if ($account->subdomain !== $request->subdomain) {
             event(new SubdomainWasUpdated($account));
+        }
 
         $account->fill($request->all());
         $account->client_view_css = $request->client_view_css;
diff --git a/app/Models/LookupAccount.php b/app/Models/LookupAccount.php
index 7d5cd8e8c12d..605769de00c6 100644
--- a/app/Models/LookupAccount.php
+++ b/app/Models/LookupAccount.php
@@ -55,4 +55,26 @@ class LookupAccount extends LookupModel
         return $this->lookupCompany->dbServer->name;
     }
 
+    public static function validateField($field, $value, $account = false)
+    {
+        if (! env('MULTI_DB_ENABLED')) {
+            return true;
+        }
+
+        $current = config('database.default');
+        
+        config(['database.default' => DB_NINJA_LOOKUP]);
+
+        $lookupAccount = LookupAccount::where($field, '=', $value)->first();
+
+        if ($account) {
+            $isValid = ! $lookupAccount || ($lookupAccount->account_key == $account->account_key);
+        } else {
+            $isValid = ! $lookupAccount;
+        }
+
+        config(['database.default' => $current]);
+
+        return $isValid;
+    }
 }
diff --git a/database/migrations/2017_11_15_114422_add_subdomain_to_lookups.php b/database/migrations/2017_11_15_114422_add_subdomain_to_lookups.php
new file mode 100644
index 000000000000..ce88a26b08e4
--- /dev/null
+++ b/database/migrations/2017_11_15_114422_add_subdomain_to_lookups.php
@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class AddSubdomainToLookups extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('lookup_accounts', function ($table) {
+            $table->string('subdomain')->nullable()->unique();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('lookup_accounts', function ($table) {
+            $table->dropColumn('subdomain');
+        });
+    }
+}
diff --git a/resources/lang/en/texts.php b/resources/lang/en/texts.php
index 315cbc56786c..cda9b7ff7225 100644
--- a/resources/lang/en/texts.php
+++ b/resources/lang/en/texts.php
@@ -2522,6 +2522,7 @@ $LANG = array(
     'set_self_hoat_url' => 'Self-Host URL',
     'local_storage_required' => 'Error: local storage is not available.',
     'your_password_reset_link' => 'Your Password Reset Link',
+    'subdomain_taken' => 'The subdomain is already in use',
 
 );