diff --git a/src/models.py b/src/models.py
index 9bcdde5..e3e8c04 100644
--- a/src/models.py
+++ b/src/models.py
@@ -46,7 +46,15 @@ class B4wExport(BaseModel):
     reference: str = Field(alias="RmtInf")
     other_name: str = Field(alias="RmtdNm")
     other_iban: str = Field(alias="RmtdAcctIBAN")
-    category: Category | None = Field(alias="Category")
+    category: Category | None = Field(
+        alias="Category",
+        examples=[
+            "Freizeit",
+            "Beruf:Gehalt:super Firma",
+            "Lebenshaltung:Lebensmitteleinkäuft",
+            "",
+        ],
+    )
     notes: str = Field(alias="Notes")
 
     @property
diff --git a/tests/factories.py b/tests/factories.py
index 5108063..f31a6fb 100644
--- a/tests/factories.py
+++ b/tests/factories.py
@@ -5,4 +5,5 @@ from src.models import B4wExport
 DEFAULT_CATEGORY = "root_category:parent_category:leaf_category"
 
 
-class B4wExportFactory(ModelFactory[B4wExport]): ...
+class B4wExportFactory(ModelFactory[B4wExport]):
+    __use_examples__ = True
diff --git a/tests/test_model_b4wexport.py b/tests/test_model_b4wexport.py
index dcff718..866fd44 100644
--- a/tests/test_model_b4wexport.py
+++ b/tests/test_model_b4wexport.py
@@ -1,13 +1,31 @@
+import pytest
+from pydantic import ValidationError
+
 from src.models import B4wExport, Category
 from tests.factories import B4wExportFactory
 
 
-def test_b4wexport_simple():
+def test_b4w_export_simple():
     data = B4wExportFactory.build()
     assert isinstance(data, B4wExport)
 
 
-def test_b4export_category():
+def test_b4w_export_category():
     data = B4wExportFactory.build(Category="fun:stuff")
     assert isinstance(data.category, Category)
     assert data.category.to_str() == "fun:stuff"
+
+
+def test_b4w_export_account_iban_invalid():
+    with pytest.raises(ValidationError):
+        _ = B4wExportFactory.build(OwnrAcctIBAN="not an IBAN")
+
+
+def test_b4w_export_account_iban_to_long():
+    with pytest.raises(ValidationError):
+        _ = B4wExportFactory.build(OwnrAcctIBAN="DE990123456789012345678901234567890")
+
+
+def test_b4w_export_account_iban_to_short():
+    with pytest.raises(ValidationError):
+        _ = B4wExportFactory.build(OwnrAcctIBAN="DE123")