diff --git a/addons/project/models/project_task_recurrence.py b/addons/project/models/project_task_recurrence.py
index 1b05d2c49bd..fe5b3737a12 100644
--- a/addons/project/models/project_task_recurrence.py
+++ b/addons/project/models/project_task_recurrence.py
@@ -8,6 +8,8 @@ from calendar import monthrange
 from dateutil.relativedelta import relativedelta
 from dateutil.rrule import rrule, rruleset, DAILY, WEEKLY, MONTHLY, YEARLY, MO, TU, WE, TH, FR, SA, SU
 
+import math
+
 MONTHS = {
     'january': 31,
     'february': 28,
@@ -179,7 +181,7 @@ class ProjectTaskRecurrence(models.Model):
                 start = date_start - relativedelta(days=1)
                 if repeat_type == 'until' and repeat_until > date_start:
                     delta = relativedelta(repeat_until, date_start)
-                    count = delta.years * 12 + delta.months
+                    count = math.floor((delta.years * 12 + delta.months) / repeat_interval)
                 for i in range(count):
                     start = start.replace(day=min(repeat_day, monthrange(start.year, start.month)[1]))
                     if i == 0 and start < date_start:
diff --git a/addons/project/tests/test_project_recurrence.py b/addons/project/tests/test_project_recurrence.py
index 4508545ec3f..216673e7360 100644
--- a/addons/project/tests/test_project_recurrence.py
+++ b/addons/project/tests/test_project_recurrence.py
@@ -437,6 +437,24 @@ class TestProjectrecurrence(TransactionCase):
         self.assertEqual(dates[3], datetime(2020, 4, 25))
         self.assertEqual(dates[4], datetime(2020, 5, 23))
 
+        dates = self.env['project.task.recurrence']._get_next_recurring_dates(
+            date_start=datetime(2020, 1, 10),
+            repeat_interval=6, # twice a year
+            repeat_unit='month',
+            repeat_type='until',
+            repeat_until=datetime(2021, 1, 11),
+            repeat_on_month='date',
+            repeat_on_year=False,
+            weekdays=[TH(+1)],
+            repeat_day='3', # the 3rd of the month
+            repeat_week=False,
+            repeat_month=False,
+            count=1)
+
+        self.assertEqual(len(dates), 2)
+        self.assertEqual(dates[0], datetime(2020, 7, 3))
+        self.assertEqual(dates[1], datetime(2021, 1, 3))
+
     def test_recurrence_next_dates_year(self):
         dates = self.env['project.task.recurrence']._get_next_recurring_dates(
             date_start=date(2020, 12, 1),