diff --git a/app/Models/Activity.php b/app/Models/Activity.php
index 49bcc1e..7e06d88 100644
--- a/app/Models/Activity.php
+++ b/app/Models/Activity.php
@@ -63,6 +63,9 @@ class Activity extends Model
 				$data->updatePersentaseProgress();
 				$data->updateCostActual();
 			}
+			if($this->start_date != request()->start_date || $this->end_date != request()->end_date) {
+				$data->updateStartEndDateHeader();
+			}
 		});
 
 		static::deleted(function($data) {
@@ -75,6 +78,9 @@ class Activity extends Model
 				$data->updatePersentaseProgress();
 				$data->updateCostActual();
 			}
+			if($this->start_date != request()->start_date || $this->end_date != request()->end_date) {
+				$data->updateStartEndDateHeader();
+			}
 		});
 
 	}
@@ -160,6 +166,18 @@ class Activity extends Model
 		]);
 	}
 
+	private function updateStartEndDateHeader()
+	{
+		$earliestStartDate = Activity::where('version_gantt_id', $this->version_gantt_id)->oldest('start_date')->pluck('start_date')->first();
+		$latestEndDate = Activity::where('version_gantt_id', $this->version_gantt_id)->latest('end_date')->pluck('end_date')->first();
+		if($header = Activity::where('version_gantt_id', $this->version_gantt_id)->whereNull('parent_id')->first()) {
+			$header->update([
+				"start_date" => $earliestStartDate,
+				"end_date" => $latestEndDate
+			]);
+		}
+	}
+
 	public function getJobsDoneAttribute()
 	{
         if(!ReportActivityMaterial::where('activity_id', $this->id)->first())