diff --git a/ihatemoney/forms.py b/ihatemoney/forms.py
index 11ce57a9..ec5bd0df 100644
--- a/ihatemoney/forms.py
+++ b/ihatemoney/forms.py
@@ -364,7 +364,7 @@ class BillForm(FlaskForm):
     payed_for = SelectMultipleField(
         _("For whom?"), validators=[DataRequired()], coerce=int
     )
-    bill_type = SelectField(_("Bill Type"), validators=[DataRequired()], choices=BillType.choices(), coerce=BillType)
+    bill_type = SelectField(_("Bill Type"), choices=BillType.choices(), coerce=BillType, default=BillType.EXPENSE)
     submit = SubmitField(_("Submit"))
     submit2 = SubmitField(_("Submit and add a new one"))
 
diff --git a/ihatemoney/tests/api_test.py b/ihatemoney/tests/api_test.py
index f3f1d61a..ff94ebe7 100644
--- a/ihatemoney/tests/api_test.py
+++ b/ihatemoney/tests/api_test.py
@@ -1047,4 +1047,33 @@ class TestAPI(IhatemoneyTestCase):
             headers=self.get_auth("raclette")
         )
 
-        self.assertStatus(201, req)
\ No newline at end of file
+        self.assertStatus(201, req)
+
+    def test_default_bill_type(self):
+        self.api_create("raclette")
+        self.api_add_member("raclette", "zorglub")
+
+        # Post a bill without adding a bill type
+        req = self.client.post(
+            "/api/projects/raclette/bills",
+            data={
+                "date": "2011-08-10",
+                "what": "fromage",
+                "payer": "1",
+                "payed_for": ["1"],
+                "amount": "50",
+            },
+            headers=self.get_auth("raclette")
+        )
+
+        self.assertStatus(201, req)
+
+        req = self.client.get(
+            "/api/projects/raclette/bills/1", headers=self.get_auth("raclette")
+        )
+        self.assertStatus(200, req)
+
+        # Bill type should now be "Expense"
+        got = json.loads(req.data.decode("utf-8"))
+        assert got["bill_type"] == "Expense"
+