diff --git a/addons/at_accounting/models/executive_summary_report.py b/addons/at_accounting/models/executive_summary_report.py
new file mode 100644
index 0000000..f048a4f
--- /dev/null
+++ b/addons/at_accounting/models/executive_summary_report.py
@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import fields, models
+from odoo.exceptions import UserError
+
+class ExecutiveSummaryReport(models.Model):
+    _inherit = 'account.report'
+
+    def _report_custom_engine_executive_summary_ndays(self, expressions, options, date_scope, current_groupby, next_groupby, offset=0, limit=None, warnings=None):
+        if current_groupby or next_groupby:
+            raise UserError("NDays expressions of executive summary report don't support the 'group by' feature.")
+
+        date_diff = fields.Date.from_string(options['date']['date_to']) - fields.Date.from_string(options['date']['date_from'])
+        return {'result': date_diff.days}