diff --git a/backend/controllers/parking/bookings.controller.ts b/backend/controllers/parking/bookings.controller.ts
index 57bbd82e..9cb52ec5 100644
--- a/backend/controllers/parking/bookings.controller.ts
+++ b/backend/controllers/parking/bookings.controller.ts
@@ -440,6 +440,15 @@ class ParkingBookingsController {
         return
       }
 
+      if (errorMessage === ERROR_CODES.PARKING_INVALID_DATES) {
+        res.status(400).json({
+          success: false,
+          error: ERROR_CODES.PARKING_INVALID_DATES,
+          code: ERROR_CODES.PARKING_INVALID_DATES,
+        })
+        return
+      }
+
       if (errorMessage.includes('No se puede hacer check-out')) {
         res.status(400).json({
           success: false,
diff --git a/backend/repositories/parking/bookings.repository.ts b/backend/repositories/parking/bookings.repository.ts
index b7b134e7..d2d56325 100644
--- a/backend/repositories/parking/bookings.repository.ts
+++ b/backend/repositories/parking/bookings.repository.ts
@@ -3,6 +3,7 @@
 // Versión profesional con booking_code
 // ============================================
 import pool from '../../config/db.js'
+import { ERROR_CODES } from '../../config/error-codes.js'
 import { targetSpot, type SpotRef } from '../../services/parking/target-spot.js'
 import { ResultSetHeader, RowDataPacket, type PoolConnection } from 'mysql2/promise'
 import type {
@@ -467,6 +468,12 @@ class ParkingBookingsRepository {
         throw new Error(`No se puede hacer check-out: estado actual es '${booking[0].status}'`)
       }
 
+      // The check-out cannot be earlier than the check-in it closes
+      const checkin = booking[0].actual_checkin
+      if (checkin && actual_checkout.getTime() < new Date(checkin).getTime()) {
+        throw new Error(ERROR_CODES.PARKING_INVALID_DATES)
+      }
+
       const payment_date = payment_amount ? new Date() : null
 
       await connection.query(
diff --git a/backend/tests/parking/checkout-dates.test.ts b/backend/tests/parking/checkout-dates.test.ts
new file mode 100644
index 00000000..70257a2e
--- /dev/null
+++ b/backend/tests/parking/checkout-dates.test.ts
@@ -0,0 +1,53 @@
+// tests/parking/checkout-dates.test.ts
+// Regression tests for PUT /api/parking/bookings/:code/checkout: the real
+// check-out date was only checked for being readable, so a check-out earlier
+// than its check-in was stored. It is now refused with PARKING_INVALID_DATES.
+
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+
+const connection = {
+  beginTransaction: vi.fn(),
+  commit: vi.fn(),
+  rollback: vi.fn(),
+  release: vi.fn(),
+  query: vi.fn(),
+}
+
+vi.mock('../../config/db.js', () => ({
+  default: { getConnection: vi.fn(async () => connection), query: vi.fn() },
+}))
+
+const { default: repository } = await import('../../repositories/parking/bookings.repository.js')
+const { ERROR_CODES } = await import('../../config/error-codes.js')
+
+const checkin = new Date('2026-10-10T12:00:00Z')
+const booked = [[{ id: 7, status: 'checked_in', actual_checkin: checkin }]]
+
+describe('checkOut dates', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    connection.query.mockReset()
+    vi.restoreAllMocks()
+  })
+
+  it('refuses a check-out earlier than the check-in and writes nothing', async () => {
+    connection.query.mockResolvedValueOnce(booked)
+
+    await expect(
+      repository.checkOut(7, { actual_checkout: new Date('2026-10-10T11:59:00Z') })
+    ).rejects.toThrow(ERROR_CODES.PARKING_INVALID_DATES)
+    expect(connection.query).toHaveBeenCalledOnce() // only the SELECT
+    expect(connection.rollback).toHaveBeenCalledOnce()
+    expect(connection.commit).not.toHaveBeenCalled()
+  })
+
+  it('accepts a check-out equal to or later than the check-in', async () => {
+    vi.spyOn(repository, 'findById').mockResolvedValue(null)
+    for (const at of ['2026-10-10T12:00:00Z', '2026-10-12T09:00:00Z']) {
+      connection.query.mockResolvedValueOnce(booked).mockResolvedValueOnce([{ affectedRows: 1 }])
+      await repository.checkOut(7, { actual_checkout: new Date(at) })
+    }
+    expect(connection.commit).toHaveBeenCalledTimes(2)
+    expect(connection.rollback).not.toHaveBeenCalled()
+  })
+})
diff --git a/docs/TODO.md b/docs/TODO.md
index 473ba85c..a7da927e 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -145,10 +145,6 @@ preview.
 - [ ] **Logbook: la fecha de una entrada admite cualquier día** — pasado o
       futuro, sin límite. Decidir qué rango tiene sentido. _Comprobado por mí el
       2026-09-28._
-- [ ] **Parking: entrada y salida aceptan fechas reales arbitrarias** — el
-      cuerpo del `PUT` ya se valida con Zod (2026-10-02), pero las fechas de
-      entrada y salida reales no. _Según la revisión `security` L3 del
-      2026-09-28 (fichero y línea en el informe); no repasado por mí._
 - [ ] **Parking: `GET /vehicles` vuelca todos los vehículos** (matrícula y
       titular) sin paginar ni filtrar. _Según la revisión `security` L3 del
       2026-09-28 (fichero y línea en el informe); no repasado por mí._