diff --git a/app/app/Console/Commands/ResetMonthlyCountersCommand.php b/app/app/Console/Commands/ResetMonthlyCountersCommand.php
new file mode 100644
index 00000000..ce84c3bf
--- /dev/null
+++ b/app/app/Console/Commands/ResetMonthlyCountersCommand.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Console\Commands;
+
+use Illuminate\Console\Command;
+use Illuminate\Support\Facades\DB;
+
+/**
+ * Сброс tenants.delivered_in_month + projects.delivered_in_month = 0.
+ *
+ * Spec: docs/superpowers/specs/2026-05-11-plan4-billing-csv-admin-design.md §4.1
+ * Расписание: 1-го числа каждого месяца в 00:00 Europe/Moscow.
+ *
+ * Идёт через connection `pgsql_supplier` (BYPASSRLS-роль crm_supplier_worker) —
+ * паттерн ResetDeliveredTodayCommand. Один statement на таблицу, без SET LOCAL.
+ */
+class ResetMonthlyCountersCommand extends Command
+{
+    protected $signature = 'projects:reset-monthly';
+
+    protected $description = 'Сброс tenants.delivered_in_month + projects.delivered_in_month = 0 (1-го числа в 00:00 МСК, Plan 4)';
+
+    public function handle(): int
+    {
+        // Без оборачивающего DB::transaction: два UPDATE'а независимо идемпотентны
+        // (WHERE delivered_in_month <> 0). Если один упадёт, следующий cron-запуск
+        // довершит сброс. Атомарность не требуется. Дополнительно — оборачивание
+        // ломает тесты с shared PDO (SharesSupplierPdo trait): PostgreSQL не
+        // допускает nested transactions без savepoints, см. precedent
+        // ResetDeliveredTodayCommand (тоже без обёртки).
+        $tenants = DB::connection('pgsql_supplier')
+            ->update('UPDATE tenants  SET delivered_in_month = 0 WHERE delivered_in_month <> 0');
+        $projects = DB::connection('pgsql_supplier')
+            ->update('UPDATE projects SET delivered_in_month = 0 WHERE delivered_in_month <> 0');
+
+        $this->info("Monthly reset: {$tenants} tenants, {$projects} projects.");
+
+        return self::SUCCESS;
+    }
+}
diff --git a/app/phpstan-baseline.neon b/app/phpstan-baseline.neon
index bbf0d6aa..1077fac6 100644
--- a/app/phpstan-baseline.neon
+++ b/app/phpstan-baseline.neon
@@ -414,6 +414,18 @@ parameters:
 			count: 2
 			path: tests/Feature/Console/ResetDeliveredTodayCommandTest.php
 
+		-
+			message: '#^Access to an undefined property App\\Models\\Tenant\:\:\$delivered_in_month\.$#'
+			identifier: property.notFound
+			count: 3
+			path: tests/Feature/Console/ResetMonthlyCountersCommandTest.php
+
+		-
+			message: '#^Call to an undefined method Pest\\PendingCalls\\TestCall\:\:artisan\(\)\.$#'
+			identifier: method.notFound
+			count: 1
+			path: tests/Feature/Console/ResetMonthlyCountersCommandTest.php
+
 		-
 			message: '#^Access to an undefined property Pest\\PendingCalls\\TestCall\:\:\$tenant\.$#'
 			identifier: property.notFound
diff --git a/app/routes/console.php b/app/routes/console.php
index e7d6874b..6bfd070b 100644
--- a/app/routes/console.php
+++ b/app/routes/console.php
@@ -22,6 +22,11 @@ Schedule::command('projects:reset-delivered-today')
     ->dailyAt('00:00')
     ->timezone('Europe/Moscow');
 
+// Plan 4: monthly reset 1-го числа в 00:00 МСК для tier-lookup в LedgerService.
+Schedule::command('projects:reset-monthly')
+    ->monthlyOn(1, '00:00')
+    ->timezone('Europe/Moscow');
+
 // Plan 3 Task 8: 5 Schedule entries для supplier-flow.
 //
 // NB: ->onOneServer() требует cache_locks таблицу, которой у нас нет
diff --git a/app/tests/Feature/Console/ResetMonthlyCountersCommandTest.php b/app/tests/Feature/Console/ResetMonthlyCountersCommandTest.php
new file mode 100644
index 00000000..3d472376
--- /dev/null
+++ b/app/tests/Feature/Console/ResetMonthlyCountersCommandTest.php
@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Project;
+use App\Models\Tenant;
+use Illuminate\Console\Scheduling\Schedule;
+use Illuminate\Foundation\Testing\DatabaseTransactions;
+use Illuminate\Support\Facades\Artisan;
+use Illuminate\Support\Facades\DB;
+use Tests\Concerns\SharesSupplierPdo;
+
+uses(DatabaseTransactions::class);
+uses(SharesSupplierPdo::class);
+
+beforeEach(function () {
+    DB::statement("SELECT set_config('app.current_tenant_id', '0', true)");
+});
+
+it('resets tenants.delivered_in_month and projects.delivered_in_month to 0', function () {
+    $tenantA = Tenant::factory()->create(['delivered_in_month' => 100]);
+    $tenantB = Tenant::factory()->create(['delivered_in_month' => 5]);
+    $tenantC = Tenant::factory()->create(['delivered_in_month' => 0]);
+
+    Project::factory()->create(['tenant_id' => $tenantA->id, 'delivered_in_month' => 50]);
+    Project::factory()->create(['tenant_id' => $tenantA->id, 'delivered_in_month' => 50]);
+    Project::factory()->create(['tenant_id' => $tenantB->id, 'delivered_in_month' => 5]);
+
+    Artisan::call('projects:reset-monthly');
+
+    expect($tenantA->fresh()->delivered_in_month)->toBe(0);
+    expect($tenantB->fresh()->delivered_in_month)->toBe(0);
+    expect($tenantC->fresh()->delivered_in_month)->toBe(0);
+
+    expect(Project::sum('delivered_in_month'))->toBe(0);
+});
+
+it('is idempotent — second run reports 0 affected', function () {
+    $tenant = Tenant::factory()->create(['delivered_in_month' => 10]);
+    Project::factory()->create(['tenant_id' => $tenant->id, 'delivered_in_month' => 10]);
+
+    // Первый прогон сбрасывает оба счётчика.
+    Artisan::call('projects:reset-monthly');
+
+    // Второй прогон должен сообщить о 0 затронутых строках (WHERE delivered_in_month <> 0).
+    // info() пишет ОДНУ строку «Monthly reset: 0 tenants, 0 projects.» —
+    // expectsOutputToContain в Laravel 13 line-by-line, поэтому проверяем
+    // обе подстроки одним substring'ом.
+    $this->artisan('projects:reset-monthly')
+        ->expectsOutputToContain('0 tenants, 0 projects')
+        ->assertExitCode(0);
+});
+
+it('Schedule entry registered for monthly on 1st 00:00 Europe/Moscow', function () {
+    /** @var Schedule $schedule */
+    $schedule = app(Schedule::class);
+
+    $found = collect($schedule->events())->first(
+        fn ($event) => str_contains($event->command ?? '', 'projects:reset-monthly')
+    );
+
+    expect($found)->not->toBeNull();
+    expect($found->expression)->toBe('0 0 1 * *');
+    expect($found->timezone)->toBe('Europe/Moscow');
+});
+
+it('uses pgsql_supplier BYPASSRLS connection (touches all tenants without SET LOCAL)', function () {
+    Tenant::factory()->count(3)->create(['delivered_in_month' => 7]);
+
+    // Без SET LOCAL app.current_tenant_id reset должен затронуть всех 3 tenant'ов.
+    // Это тест на использование pgsql_supplier (BYPASSRLS), не default pgsql.
+    Artisan::call('projects:reset-monthly');
+
+    expect(Tenant::where('delivered_in_month', '>', 0)->count())->toBe(0);
+});