diff --git a/accountant/models/accounts.py b/accountant/models/accounts.py
index d7640d8..27d7647 100644
--- a/accountant/models/accounts.py
+++ b/accountant/models/accounts.py
@@ -85,6 +85,45 @@ class Account(db.Model):
 
         return query.one()
 
+    def category_incomes(self, begin=None, end=None):
+        """Return a query for categories with expenses, revenues and income for
+        this account and an optional specific time period."""
+
+        query = db.session.query(
+            Operation.category.label('category'),
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).filter(
+                    db.func.sign(Operation.value) == -1
+                ),
+                0
+            ).label("expenses"),
+            db.func.coalesce(
+                db.func.sum(
+                    Operation.value
+                ).filter(
+                    db.func.sign(Operation.value) == 1
+                ),
+                0
+            ).label("revenues"),
+            db.func.sum(Operation.value).label("income")
+        ).filter(
+            Operation.account_id == self.id
+        ).order_by(
+            Operation.category
+        ).group_by(
+            Operation.category
+        )
+
+        if begin:
+            query = query.filter(Operation.operation_date >= str(begin))
+
+        if end:
+            query = query.filter(Operation.operation_date <= str(end))
+
+        return query
+
     @db.validates('authorized_overdraft')
     def validate_authorized_overdraft(self, key, authorized_overdraft):
         """Validator for authorized_overdraft : must be negative."""
diff --git a/accountant/models/operations.py b/accountant/models/operations.py
index 4a2d7ec..ae8ff06 100644
--- a/accountant/models/operations.py
+++ b/accountant/models/operations.py
@@ -133,50 +133,6 @@ class Operation(db.Model):
 
         return query
 
-    @classmethod
-    def query_category_incomes(cls, account, begin=None, end=None):
-        """Return a query for categories with expenses, revenues and income for
-        a specific account and a specific time period."""
-        if isinstance(account, (int, str)):
-            account_id = account
-        else:
-            account_id = account.id
-
-        query = db.session.query(
-            cls.category.label('category'),
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).filter(
-                    db.func.sign(cls.value) == -1
-                ),
-                0
-            ).label("expenses"),
-            db.func.coalesce(
-                db.func.sum(
-                    cls.value
-                ).filter(
-                    db.func.sign(cls.value) == 1
-                ),
-                0
-            ).label("revenues"),
-            db.func.sum(cls.value).label("income")
-        ).filter(
-            cls.account_id == account_id
-        ).order_by(
-            cls.category
-        ).group_by(
-            cls.category
-        )
-
-        if begin:
-            query = query.filter(cls.operation_date >= str(begin))
-
-        if end:
-            query = query.filter(cls.operation_date <= str(end))
-
-        return query
-
     @classmethod
     def query_daily_balances(cls, account, begin=None, end=None):
         """Get expenses, revenues, income and balance per day for a specific
diff --git a/accountant/views/accounts.py b/accountant/views/accounts.py
index 5714afb..f769c7d 100644
--- a/accountant/views/accounts.py
+++ b/accountant/views/accounts.py
@@ -328,8 +328,13 @@ class CategoryResource(Resource):
         data = range_parser.parse_args()
         # FIXME Alexis Lahouze 2017-05-23 check data.
 
+        account = Account.query().get(account_id)
+
+        if not account:
+            ns.abort(404, 'Account with id %d not found.' % account_id)
+
         return list(result_as_dicts(
-            Operation.query_category_incomes(account_id, **data)
+            account.category_incomes(**data)
         )), 200