diff --git a/course/lib.php b/course/lib.php
index c255e555347..a20a219577c 100644
--- a/course/lib.php
+++ b/course/lib.php
@@ -3710,6 +3710,41 @@ function core_course_inplace_editable($itemtype, $itemid, $newvalue) {
     }
 }
 
+/**
+ * This function calculates the minimum and maximum cutoff values for the timestart of
+ * the given event.
+ *
+ * It will return an array with two values, the first being the minimum cutoff value and
+ * the second being the maximum cutoff value. Either or both values can be null, which
+ * indicates there is no minimum or maximum, respectively.
+ *
+ * If a cutoff is required then the function must return an array containing the cutoff
+ * timestamp and error string to display to the user if the cutoff value is violated.
+ *
+ * A minimum and maximum cutoff return value will look like:
+ * [
+ *     [1505704373, 'The date must be after this date'],
+ *     [1506741172, 'The date must be before this date']
+ * ]
+ *
+ * @param calendar_event $event The calendar event to get the time range for
+ * @param stdClass $course The course object to get the range from
+ * @return array Returns an array with min and max date.
+ */
+function core_course_core_calendar_get_valid_event_timestart_range(\calendar_event $event, $course) {
+    $mindate = null;
+    $maxdate = null;
+
+    if ($course->startdate) {
+        $mindate = [
+            $course->startdate,
+            get_string('errorbeforecoursestart', 'calendar')
+        ];
+    }
+
+    return [$mindate, $maxdate];
+}
+
 /**
  * Returns course modules tagged with a specified tag ready for output on tag/index.php page
  *
diff --git a/course/tests/courselib_test.php b/course/tests/courselib_test.php
index 297e54b4c85..1bdf3b52d25 100644
--- a/course/tests/courselib_test.php
+++ b/course/tests/courselib_test.php
@@ -4717,4 +4717,55 @@ class core_course_courselib_testcase extends advanced_testcase {
         $this->assertEquals($expectedcourses, $actual);
         $this->assertEquals($expectedprocessedcount, $processedcount);
     }
+
+
+    /**
+     * Testing core_course_core_calendar_get_valid_event_timestart_range when the course has no end date.
+     */
+    public function test_core_course_core_calendar_get_valid_event_timestart_range_no_enddate() {
+        global $CFG;
+        require_once($CFG->dirroot . "/calendar/lib.php");
+
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+        $generator = $this->getDataGenerator();
+        $now = time();
+        $course = $generator->create_course(['startdate' => $now - 86400]);
+
+        // Create a course event.
+        $event = new \calendar_event([
+            'name' => 'Test course event',
+            'eventtype' => 'course',
+            'courseid' => $course->id,
+        ]);
+
+        list ($min, $max) = core_course_core_calendar_get_valid_event_timestart_range($event, $course);
+        $this->assertEquals($course->startdate, $min[0]);
+        $this->assertNull($max);
+    }
+
+    /**
+     * Testing core_course_core_calendar_get_valid_event_timestart_range when the course has end date.
+     */
+    public function test_core_course_core_calendar_get_valid_event_timestart_range_with_enddate() {
+        global $CFG;
+        require_once($CFG->dirroot . "/calendar/lib.php");
+
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+        $generator = $this->getDataGenerator();
+        $now = time();
+        $course = $generator->create_course(['startdate' => $now - 86400, 'enddate' => $now + 86400]);
+
+        // Create a course event.
+        $event = new \calendar_event([
+            'name' => 'Test course event',
+            'eventtype' => 'course',
+            'courseid' => $course->id,
+        ]);
+
+        list ($min, $max) = core_course_core_calendar_get_valid_event_timestart_range($event, $course);
+        $this->assertEquals($course->startdate, $min[0]);
+        $this->assertNull($max);
+    }
 }