diff --git a/domain/marketplace/classified_ad.py b/domain/marketplace/classified_ad.py
index 22ab7ec..ab9ec4e 100644
--- a/domain/marketplace/classified_ad.py
+++ b/domain/marketplace/classified_ad.py
@@ -11,4 +11,4 @@ class ClassifiedAd:
     _ownerId: UserId
     title: str
     text: str
-    _price: Decimal
+    _price: Decimal = Decimal("0.00")
diff --git a/tests/test_classified_ad.py b/tests/test_classified_ad.py
index 0d3b884..5775d51 100644
--- a/tests/test_classified_ad.py
+++ b/tests/test_classified_ad.py
@@ -1,6 +1,8 @@
 from decimal import Decimal
 from uuid import uuid4
 
+import pytest
+
 from domain.marketplace.classified_ad import ClassifiedAd
 from domain.marketplace.user_id import UserId
 
@@ -24,6 +26,41 @@ def test_classified_ad_creation():
     assert ad._price == Decimal("99.99")
 
 
+def test_classified_ad_can_not_be_created_without_id():
+    with pytest.raises(TypeError):
+        ad = ClassifiedAd(
+            _ownerId=UserId(value=uuid4()),
+            title="Title",
+            text="Text",
+            _price=Decimal("10.00"),
+        )
+
+def test_classified_ad_can_not_be_created_without_owner_id():
+    with pytest.raises(TypeError):
+        ad = ClassifiedAd(
+            id=UserId(value=uuid4()),
+            title="Title",
+            text="Text",
+            _price=Decimal("10.00"),
+        )
+
+def test_classified_ad_can_be_created_without_price():
+    ad_id = uuid4()
+    owner_id = UserId(value=uuid4())
+
+    ad = ClassifiedAd(
+        id=ad_id,
+        _ownerId=owner_id,
+        title="Test Title",
+        text="Test text content",
+    )
+
+    assert ad.id == ad_id
+    assert ad._ownerId == owner_id
+    assert ad.title == "Test Title"
+    assert ad.text == "Test text content"
+    assert ad._price == Decimal("0.00")
+
 def test_classified_ad_is_immutable():
     ad = ClassifiedAd(
         id=uuid4(),