diff --git a/apps/dav/lib/CalDAV/BirthdayService.php b/apps/dav/lib/CalDAV/BirthdayService.php
index 0f6e819bcc..9629a62e7c 100644
--- a/apps/dav/lib/CalDAV/BirthdayService.php
+++ b/apps/dav/lib/CalDAV/BirthdayService.php
@@ -191,10 +191,26 @@ class BirthdayService {
 		}
 
 		$unknownYear = false;
+		$originalYear = null;
 		if (!$dateParts['year']) {
-			$birthday = '1900-' . $dateParts['month'] . '-' . $dateParts['date'];
+			$birthday = '1970-' . $dateParts['month'] . '-' . $dateParts['date'];
 
 			$unknownYear = true;
+		} else {
+			$parameters = $birthday->parameters();
+			if (isset($parameters['X-APPLE-OMIT-YEAR'])) {
+				$omitYear = $parameters['X-APPLE-OMIT-YEAR'];
+				if ($dateParts['year'] === $omitYear) {
+					$birthday = '1970-' . $dateParts['month'] . '-' . $dateParts['date'];
+					$unknownYear = true;
+				}
+			} else {
+				$originalYear = (int)$dateParts['year'];
+
+				if ($originalYear < 1970) {
+					$birthday = '1970-' . $dateParts['month'] . '-' . $dateParts['date'];
+				}
+			}
 		}
 
 		try {
@@ -205,8 +221,7 @@ class BirthdayService {
 		if ($unknownYear) {
 			$summary = $doc->FN->getValue() . ' ' . $summarySymbol;
 		} else {
-			$year = (int)$date->format('Y');
-			$summary = $doc->FN->getValue() . " ($summarySymbol$year)";
+			$summary = $doc->FN->getValue() . " ($summarySymbol$originalYear)";
 		}
 		$vCal = new VCalendar();
 		$vCal->VERSION = '2.0';
@@ -226,6 +241,11 @@ class BirthdayService {
 		$vEvent->{'RRULE'} = 'FREQ=YEARLY';
 		$vEvent->{'SUMMARY'} = $summary;
 		$vEvent->{'TRANSP'} = 'TRANSPARENT';
+		$vEvent->{'X-NEXTCLOUD-BC-FIELD-TYPE'} = $dateField;
+		$vEvent->{'X-NEXTCLOUD-BC-UNKNOWN-YEAR'} = $unknownYear ? '1' : '0';
+		if ($originalYear !== null) {
+			$vEvent->{'X-NEXTCLOUD-BC-YEAR'} = (string) $originalYear;
+		}
 		$alarm = $vCal->createComponent('VALARM');
 		$alarm->add($vCal->createProperty('TRIGGER', '-PT0M', ['VALUE' => 'DURATION']));
 		$alarm->add($vCal->createProperty('ACTION', 'DISPLAY'));
diff --git a/apps/dav/tests/unit/CardDAV/BirthdayServiceTest.php b/apps/dav/tests/unit/CardDAV/BirthdayServiceTest.php
index 651fbf5eaf..3461c4af3b 100644
--- a/apps/dav/tests/unit/CardDAV/BirthdayServiceTest.php
+++ b/apps/dav/tests/unit/CardDAV/BirthdayServiceTest.php
@@ -60,10 +60,14 @@ class BirthdayServiceTest extends TestCase {
 
 	/**
 	 * @dataProvider providesVCards
-	 * @param boolean $expectedSummary
+	 * @param string $expectedSummary
+	 * @param string $expectedDTStart
+	 * @param string $expectedFieldType
+	 * @param string $expectedUnknownYear
+	 * @param string $expectedOriginalYear
 	 * @param string | null $data
 	 */
-	public function testBuildBirthdayFromContact($expectedSummary, $data) {
+	public function testBuildBirthdayFromContact($expectedSummary, $expectedDTStart, $expectedFieldType, $expectedUnknownYear, $expectedOriginalYear, $data) {
 		$cal = $this->service->buildDateFromContact($data, 'BDAY', '', '*');
 		if ($expectedSummary === null) {
 			$this->assertNull($cal);
@@ -72,6 +76,14 @@ class BirthdayServiceTest extends TestCase {
 			$this->assertTrue(isset($cal->VEVENT));
 			$this->assertEquals('FREQ=YEARLY', $cal->VEVENT->RRULE->getValue());
 			$this->assertEquals($expectedSummary, $cal->VEVENT->SUMMARY->getValue());
+			$this->assertEquals($expectedDTStart, $cal->VEVENT->DTSTART->getValue());
+			$this->assertEquals($expectedFieldType, $cal->VEVENT->{'X-NEXTCLOUD-BC-FIELD-TYPE'}->getValue());
+			$this->assertEquals($expectedUnknownYear, $cal->VEVENT->{'X-NEXTCLOUD-BC-UNKNOWN-YEAR'}->getValue());
+
+			if ($expectedOriginalYear) {
+				$this->assertEquals($expectedOriginalYear, $cal->VEVENT->{'X-NEXTCLOUD-BC-YEAR'}->getValue());
+			}
+
 			$this->assertEquals('TRANSPARENT', $cal->VEVENT->TRANSP->getValue());
 		}
 	}
@@ -338,19 +350,20 @@ class BirthdayServiceTest extends TestCase {
 
 	public function providesVCards() {
 		return [
-			[null, null],
-			[null, ''],
-			[null, 'yasfewf'],
-			[null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			[null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			[null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:someday\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			['12345 (*1900)', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:19000101\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			['12345 (*1900)', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:19001231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			['12345 *', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:--1231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			['12345 *', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY;X-APPLE-OMIT-YEAR=1604:16041231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			[null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:;VALUE=text:circa 1800\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			[null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nN:12345;;;;\r\nBDAY:20031231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
-			['12345 (*900)', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:09001231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			// $expectedSummary, $expectedDTStart, $expectedFieldType, $expectedUnknownYear, $expectedOriginalYear, $data
+			[null, null, null, null, null, null],
+			[null, null, null, null, null, ''],
+			[null, null, null, null, null, 'yasfewf'],
+			[null, null, null, null, null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			[null, null, null, null, null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			[null, null, null, null, null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:someday\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			['12345 (*1900)', '19700101', 'BDAY', '0', '1900', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:19000101\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			['12345 (*1900)', '19701231', 'BDAY', '0', '1900', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:19001231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			['12345 *', '19701231', 'BDAY', '1', null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:--1231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			['12345 *', '19701231', 'BDAY', '1', null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY;X-APPLE-OMIT-YEAR=1604:16041231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			[null, null, null, null, null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:;VALUE=text:circa 1800\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			[null, null, null, null, null, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nN:12345;;;;\r\nBDAY:20031231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
+			['12345 (*900)', '19701231', 'BDAY', '0', '900', "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 4.1.1//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nBDAY:09001231\r\nEND:VCARD\r\n", "Dr. Foo Bar"],
 		];
 	}
 }