diff --git a/apps/dav/appinfo/application.php b/apps/dav/appinfo/application.php
index df3bd34d47..7a201e1dd7 100644
--- a/apps/dav/appinfo/application.php
+++ b/apps/dav/appinfo/application.php
@@ -111,6 +111,15 @@ class Application extends App {
 				$c->query('CalDavBackend')
 			);
 		});
+
+		$container->registerService('BirthdayService', function($c) {
+			/** @var IAppContainer $c */
+			return new BirthdayService(
+				$c->query('CalDavBackend'),
+				$c->query('CardDavBackend')
+			);
+
+		});
 	}
 
 	/**
@@ -130,10 +139,7 @@ class Application extends App {
 
 		$listener = function($event) {
 			if ($event instanceof GenericEvent) {
-				$b = new BirthdayService(
-					$this->getContainer()->query('CalDavBackend'),
-					$this->getContainer()->query('CardDavBackend')
-				);
+				$b = $this->getContainer()->query('BirthdayService');
 				$b->onCardChanged(
 					$event->getArgument('addressBookId'),
 					$event->getArgument('cardUri'),
@@ -147,10 +153,7 @@ class Application extends App {
 		$dispatcher->addListener('\OCA\DAV\CardDAV\CardDavBackend::updateCard', $listener);
 		$dispatcher->addListener('\OCA\DAV\CardDAV\CardDavBackend::deleteCard', function($event) {
 			if ($event instanceof GenericEvent) {
-				$b = new BirthdayService(
-					$this->getContainer()->query('CalDavBackend'),
-					$this->getContainer()->query('CardDavBackend')
-				);
+				$b = $this->getContainer()->query('BirthdayService');
 				$b->onCardDeleted(
 					$event->getArgument('addressBookId'),
 					$event->getArgument('cardUri')
diff --git a/apps/dav/appinfo/register_command.php b/apps/dav/appinfo/register_command.php
index 963bea16ca..e07f6b4a25 100644
--- a/apps/dav/appinfo/register_command.php
+++ b/apps/dav/appinfo/register_command.php
@@ -24,6 +24,7 @@ use OCA\DAV\Command\CreateAddressBook;
 use OCA\DAV\Command\CreateCalendar;
 use OCA\Dav\Command\MigrateAddressbooks;
 use OCA\Dav\Command\MigrateCalendars;
+use OCA\DAV\Command\SyncBirthdayCalendar;
 use OCA\DAV\Command\SyncSystemAddressBook;
 
 $dbConnection = \OC::$server->getDatabaseConnection();
@@ -37,6 +38,7 @@ $app = new Application();
 $application->add(new CreateCalendar($userManager, $groupManager, $dbConnection));
 $application->add(new CreateAddressBook($userManager, $app->getContainer()->query('CardDavBackend')));
 $application->add(new SyncSystemAddressBook($app->getSyncService()));
+$application->add(new SyncBirthdayCalendar($userManager, $app->getContainer()->query('BirthdayService')));
 
 // the occ tool is *for now* only available in debug mode for developers to test
 if ($config->getSystemValue('debug', false)){
diff --git a/apps/dav/command/syncbirthdaycalendar.php b/apps/dav/command/syncbirthdaycalendar.php
new file mode 100644
index 0000000000..66ab540b9a
--- /dev/null
+++ b/apps/dav/command/syncbirthdaycalendar.php
@@ -0,0 +1,85 @@
+<?php
+/**
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace OCA\DAV\Command;
+
+use OCA\DAV\CalDAV\BirthdayService;
+use OCP\IUser;
+use OCP\IUserManager;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Helper\ProgressBar;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class SyncBirthdayCalendar extends Command {
+
+	/** @var BirthdayService */
+	private $birthdayService;
+
+	/** @var IUserManager */
+	private $userManager;
+
+	/**
+	 * @param IUserManager $userManager
+	 * @param BirthdayService $birthdayService
+	 */
+	function __construct(IUserManager $userManager, BirthdayService $birthdayService) {
+		parent::__construct();
+		$this->birthdayService = $birthdayService;
+		$this->userManager = $userManager;
+	}
+
+	protected function configure() {
+		$this
+			->setName('dav:sync-birthday-calendar')
+			->setDescription('Synchronizes the birthday calendar')
+			->addArgument('user',
+				InputArgument::OPTIONAL,
+				'User for whom the birthday calendar will be synchronized');
+	}
+
+	/**
+	 * @param InputInterface $input
+	 * @param OutputInterface $output
+	 */
+	protected function execute(InputInterface $input, OutputInterface $output) {
+		if ($input->hasArgument('user')) {
+			$user = $input->getArgument('user');
+			if (!$this->userManager->userExists($user)) {
+				throw new \InvalidArgumentException("User <$user> in unknown.");
+			}
+			$output->writeln("Start birthday calendar sync for $user");
+			$this->birthdayService->syncUser($user);
+			return;
+		}
+		$output->writeln("Start birthday calendar sync for all users ...");
+		$p = new ProgressBar($output);
+		$p->start();
+		$this->userManager->callForAllUsers(function($user) use ($p)  {
+			$p->advance();
+			/** @var IUser $user */
+			$this->birthdayService->syncUser($user->getUID());
+		});
+
+		$p->finish();
+		$output->writeln('');
+	}
+}
diff --git a/apps/dav/command/syncsystemaddressbook.php b/apps/dav/command/syncsystemaddressbook.php
index b83a37131c..b62a42d7b9 100644
--- a/apps/dav/command/syncsystemaddressbook.php
+++ b/apps/dav/command/syncsystemaddressbook.php
@@ -34,7 +34,6 @@ class SyncSystemAddressBook extends Command {
 	private $syncService;
 
 	/**
-	 * @param IUserManager $userManager
 	 * @param SyncService $syncService
 	 */
 	function __construct(SyncService $syncService) {
diff --git a/apps/dav/lib/caldav/birthdayservice.php b/apps/dav/lib/caldav/birthdayservice.php
index 5a0dfb6992..3b0a2a10e1 100644
--- a/apps/dav/lib/caldav/birthdayservice.php
+++ b/apps/dav/lib/caldav/birthdayservice.php
@@ -54,14 +54,18 @@ class BirthdayService {
 		$calendar = $this->ensureCalendarExists($principalUri, $calendarUri, []);
 		$objectUri = $book['uri'] . '-' . $cardUri. '.ics';
 		$calendarData = $this->buildBirthdayFromContact($cardData);
+		$existing = $this->calDavBackEnd->getCalendarObject($calendar['id'], $objectUri);
 		if (is_null($calendarData)) {
-			$this->calDavBackEnd->deleteCalendarObject($calendar['id'], $objectUri);
+			if (!is_null($existing)) {
+				$this->calDavBackEnd->deleteCalendarObject($calendar['id'], $objectUri);
+			}
 		} else {
-			$existing = $this->calDavBackEnd->getCalendarObject($calendar['id'], $objectUri);
 			if (is_null($existing)) {
 				$this->calDavBackEnd->createCalendarObject($calendar['id'], $objectUri, $calendarData->serialize());
 			} else {
-				$this->calDavBackEnd->updateCalendarObject($calendar['id'], $objectUri, $calendarData->serialize());
+				if ($this->birthdayEvenChanged($existing['calendardata'], $calendarData)) {
+					$this->calDavBackEnd->updateCalendarObject($calendar['id'], $objectUri, $calendarData->serialize());
+				}
 			}
 		}
 	}
@@ -148,4 +152,36 @@ class BirthdayService {
 		return $vCal;
 	}
 
+	/**
+	 * @param string $user
+	 */
+	public function syncUser($user) {
+		$books = $this->cardDavBackEnd->getAddressBooksForUser('principals/users/'.$user);
+		foreach($books as $book) {
+			$cards = $this->cardDavBackEnd->getCards($book['id']);
+			foreach($cards as $card) {
+				$this->onCardChanged($book['id'], $card['uri'], $card['carddata']);
+			}
+		}
+	}
+
+	/**
+	 * @param string $existingCalendarData
+	 * @param VCalendar $newCalendarData
+	 * @return bool
+	 */
+	public function birthdayEvenChanged($existingCalendarData, $newCalendarData) {
+		try {
+			$existingBirthday = Reader::read($existingCalendarData);
+		} catch (Exception $ex) {
+			return true;
+		}
+		if ($newCalendarData->VEVENT->DTSTART->getValue() !== $existingBirthday->VEVENT->DTSTART->getValue() ||
+			$newCalendarData->VEVENT->SUMMARY->getValue() !== $existingBirthday->VEVENT->SUMMARY->getValue()
+		) {
+			return true;
+		}
+		return false;
+	}
+
 }
diff --git a/apps/dav/tests/unit/carddav/birthdayservicetest.php b/apps/dav/tests/unit/carddav/birthdayservicetest.php
index ab10ab26c1..faf42d9e1b 100644
--- a/apps/dav/tests/unit/carddav/birthdayservicetest.php
+++ b/apps/dav/tests/unit/carddav/birthdayservicetest.php
@@ -25,6 +25,7 @@ use OCA\DAV\CalDAV\BirthdayService;
 use OCA\DAV\CalDAV\CalDavBackend;
 use OCA\DAV\CardDAV\CardDavBackend;
 use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Reader;
 use Test\TestCase;
 
 class BirthdayServiceTest extends TestCase {
@@ -98,9 +99,10 @@ class BirthdayServiceTest extends TestCase {
 
 		/** @var BirthdayService | \PHPUnit_Framework_MockObject_MockObject $service */
 		$service = $this->getMock('\OCA\DAV\CalDAV\BirthdayService',
-			['buildBirthdayFromContact'], [$this->calDav, $this->cardDav]);
+			['buildBirthdayFromContact', 'birthdayEvenChanged'], [$this->calDav, $this->cardDav]);
 
 		if ($expectedOp === 'delete') {
+			$this->calDav->expects($this->once())->method('getCalendarObject')->willReturn('');
 			$service->expects($this->once())->method('buildBirthdayFromContact')->willReturn(null);
 			$this->calDav->expects($this->once())->method('deleteCalendarObject')->with(1234, 'default-gump.vcf.ics');
 		}
@@ -110,13 +112,43 @@ class BirthdayServiceTest extends TestCase {
 		}
 		if ($expectedOp === 'update') {
 			$service->expects($this->once())->method('buildBirthdayFromContact')->willReturn(new VCalendar());
-			$this->calDav->expects($this->once())->method('getCalendarObject')->willReturn('');
+			$service->expects($this->once())->method('birthdayEvenChanged')->willReturn(true);
+			$this->calDav->expects($this->once())->method('getCalendarObject')->willReturn([
+				'calendardata' => '']);
 			$this->calDav->expects($this->once())->method('updateCalendarObject')->with(1234, 'default-gump.vcf.ics', "BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nEND:VCALENDAR\r\n");
 		}
 
 		$service->onCardChanged(666, 'gump.vcf', '');
 	}
 
+	/**
+	 * @dataProvider providesBirthday
+	 * @param $expected
+	 * @param $old
+	 * @param $new
+	 */
+	public function testBirthdayEvenChanged($expected, $old, $new) {
+		$new = Reader::read($new);
+		$this->assertEquals($expected, $this->service->birthdayEvenChanged($old, $new));
+	}
+
+	public function providesBirthday() {
+		return [
+			[true,
+				'',
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n"],
+			[false,
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n",
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n"],
+			[true,
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:4567's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n",
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n"],
+			[true,
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000101\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n",
+				"BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nCALSCALE:GREGORIAN\r\nBEGIN:VEVENT\r\nUID:12345\r\nDTSTAMP:20160218T133704Z\r\nDTSTART;VALUE=DATE:19000102\r\nDTEND;VALUE=DATE:19000102\r\nRRULE:FREQ=YEARLY\r\nSUMMARY:12345's Birthday (1900)\r\nTRANSP:TRANSPARENT\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n"]
+		];
+	}
+
 	public function providesCardChanges(){
 		return[
 			['delete'],