diff --git a/lib/Db/Card.php b/lib/Db/Card.php
index 674ee8f8a..ed710d716 100644
--- a/lib/Db/Card.php
+++ b/lib/Db/Card.php
@@ -108,7 +108,7 @@ class Card extends RelationalEntity {
 		$this->addType('archived', 'boolean');
 		$this->addType('notified', 'boolean');
 		$this->addType('deletedAt', 'integer');
-		$this->addType('duedate', 'string');
+		$this->addType('duedate', 'datetime');
 		$this->addRelation('labels');
 		$this->addRelation('assignedUsers');
 		$this->addRelation('attachments');
@@ -126,20 +126,6 @@ class Card extends RelationalEntity {
 		$this->databaseType = $type;
 	}
 
-	public function getDueDateTime(): ?DateTime {
-		return $this->duedate ? new DateTime($this->duedate) : null;
-	}
-
-	public function getDuedate($isoFormat = false): ?string {
-		$dt = $this->getDueDateTime();
-		$format = 'c';
-		if (!$isoFormat && $this->databaseType === 'mysql') {
-			$format = 'Y-m-d H:i:s';
-		}
-
-		return $dt ? $dt->format($format) : null;
-	}
-
 	public function getCalendarObject(): VCalendar {
 		$calendar = new VCalendar();
 		$event = $calendar->createComponent('VTODO');
@@ -148,7 +134,7 @@ class Card extends RelationalEntity {
 			$creationDate = new DateTime();
 			$creationDate->setTimestamp($this->createdAt);
 			$event->DTSTAMP = $creationDate;
-			$event->DUE = new DateTime($this->getDuedate(true), new DateTimeZone('UTC'));
+			$event->DUE = new DateTime($this->getDuedate()->format('c'), new DateTimeZone('UTC'));
 		}
 		$event->add('RELATED-TO', 'deck-stack-' . $this->getStackId());
 
diff --git a/lib/Db/RelationalEntity.php b/lib/Db/RelationalEntity.php
index 6e2a19ef5..8ac6ef456 100644
--- a/lib/Db/RelationalEntity.php
+++ b/lib/Db/RelationalEntity.php
@@ -72,6 +72,9 @@ class RelationalEntity extends Entity implements \JsonSerializable {
 				$propertyReflection = $reflection->getProperty($property);
 				if (!$propertyReflection->isPrivate() && !in_array($property, $this->_resolvedProperties, true)) {
 					$json[$property] = $this->getter($property);
+					if ($json[$property] instanceof \DateTimeInterface) {
+						$json[$property] = $json[$property]->format('c');
+					}
 				}
 			}
 		}
diff --git a/lib/Model/CardDetails.php b/lib/Model/CardDetails.php
index 6c51ef841..58523ab14 100644
--- a/lib/Model/CardDetails.php
+++ b/lib/Model/CardDetails.php
@@ -54,7 +54,7 @@ class CardDetails extends Card {
 		$today = new DateTime();
 		$today->setTime(0, 0);
 
-		$match_date = $this->card->getDueDateTime();
+		$match_date = $this->card->getDuedate();
 		if (!$match_date) {
 			return Card::DUEDATE_FUTURE;
 		}
diff --git a/lib/Notification/NotificationHelper.php b/lib/Notification/NotificationHelper.php
index 97b900c73..0105c03f0 100644
--- a/lib/Notification/NotificationHelper.php
+++ b/lib/Notification/NotificationHelper.php
@@ -129,7 +129,7 @@ class NotificationHelper {
 					->setSubject('card-overdue', [
 						$card->getTitle(), $board->getTitle()
 					])
-					->setDateTime(new DateTime($card->getDuedate()));
+					->setDateTime($card->getDuedate());
 				$this->notificationManager->notify($notification);
 			}
 		}
@@ -242,7 +242,7 @@ class NotificationHelper {
 		}
 		return $this->boards[$boardId];
 	}
-	
+
 	private function generateBoardShared(Board $board, string $userId): INotification {
 		$notification = $this->notificationManager->createNotification();
 		$notification
diff --git a/lib/Service/CardService.php b/lib/Service/CardService.php
index 6ee4cf081..cd45ca129 100644
--- a/lib/Service/CardService.php
+++ b/lib/Service/CardService.php
@@ -337,11 +337,11 @@ class CardService {
 		$card->setType($type);
 		$card->setOrder($order);
 		$card->setOwner($owner);
-		$card->setDuedate($duedate);
+		$card->setDuedate(new \DateTime($duedate));
 		$resetDuedateNotification = false;
 		if (
 			$card->getDuedate() === null ||
-			(new \DateTime($card->getDuedate())) != (new \DateTime($changes->getBefore()->getDuedate() ?? ''))
+			($card->getDuedate()) != ($changes->getBefore()->getDuedate())
 		) {
 			$card->setNotified(false);
 			$resetDuedateNotification = true;