diff --git a/tienda_ilusion/don_confiao/migrations/0039_sale_external_id.py b/tienda_ilusion/don_confiao/migrations/0039_sale_external_id.py
new file mode 100644
index 0000000..f1d8dbd
--- /dev/null
+++ b/tienda_ilusion/don_confiao/migrations/0039_sale_external_id.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.0.6 on 2025-07-19 15:56
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('don_confiao', '0038_alter_saleline_quantity'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='sale',
+            name='external_id',
+            field=models.CharField(blank=True, max_length=100, null=True),
+        ),
+    ]
diff --git a/tienda_ilusion/don_confiao/models.py b/tienda_ilusion/don_confiao/models.py
index 4b6c2c9..1b30425 100644
--- a/tienda_ilusion/don_confiao/models.py
+++ b/tienda_ilusion/don_confiao/models.py
@@ -105,6 +105,7 @@ class Sale(models.Model):
         related_name='Sales',
         null=True
     )
+    external_id = models.CharField(max_length=100, null=True, blank=True)
 
     def __str__(self):
         return f"{self.date} {self.customer}"
diff --git a/tienda_ilusion/don_confiao/tests/test_api.py b/tienda_ilusion/don_confiao/tests/test_api.py
index 642bf80..30bd4e0 100644
--- a/tienda_ilusion/don_confiao/tests/test_api.py
+++ b/tienda_ilusion/don_confiao/tests/test_api.py
@@ -27,12 +27,13 @@ class TestAPI(APITestCase):
         sale = Sale.objects.all()[0]
         self.assertEqual(
             sale.customer.name,
-            self.customer.name
+            self.customer.name,
         )
         self.assertEqual(
             sale.id,
             content['id']
         )
+        self.assertIsNone(sale.external_id)
 
     def test_create_sale_with_decimal(self):
         response = self._create_sale_with_decimal()