diff --git a/modules/rtp_rtcp/source/rtp_packet.cc b/modules/rtp_rtcp/source/rtp_packet.cc
index 3835452759..bd5a4c25a4 100644
--- a/modules/rtp_rtcp/source/rtp_packet.cc
+++ b/modules/rtp_rtcp/source/rtp_packet.cc
@@ -617,4 +617,13 @@ bool RtpPacket::HasExtension(ExtensionType type) const {
   return !FindExtension(type).empty();
 }
 
+bool RtpPacket::IsExtensionReserved(ExtensionType type) const {
+  uint8_t id = extensions_.GetId(type);
+  if (id == ExtensionManager::kInvalidId) {
+    // Extension not registered.
+    return false;
+  }
+  return FindExtensionInfo(id) != nullptr;
+}
+
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/rtp_packet.h b/modules/rtp_rtcp/source/rtp_packet.h
index 8c4ddf318e..67d8df4894 100644
--- a/modules/rtp_rtcp/source/rtp_packet.h
+++ b/modules/rtp_rtcp/source/rtp_packet.h
@@ -99,6 +99,10 @@ class RtpPacket {
   bool HasExtension() const;
   bool HasExtension(ExtensionType type) const;
 
+  template <typename Extension>
+  bool IsExtensionReserved() const;
+  bool IsExtensionReserved(ExtensionType type) const;
+
   template <typename Extension, typename FirstValue, typename... Values>
   bool GetExtension(FirstValue, Values...) const;
 
@@ -186,6 +190,11 @@ bool RtpPacket::HasExtension() const {
   return HasExtension(Extension::kId);
 }
 
+template <typename Extension>
+bool RtpPacket::IsExtensionReserved() const {
+  return IsExtensionReserved(Extension::kId);
+}
+
 template <typename Extension, typename FirstValue, typename... Values>
 bool RtpPacket::GetExtension(FirstValue first, Values... values) const {
   auto raw = FindExtension(Extension::kId);
diff --git a/modules/rtp_rtcp/source/rtp_packet_unittest.cc b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
index 84f5020ec3..86fdc500ff 100644
--- a/modules/rtp_rtcp/source/rtp_packet_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
@@ -952,4 +952,25 @@ TEST(RtpPacketTest,
             kFeedbackRequest->sequence_count);
 }
 
+TEST(RtpPacketTest, IsExtensionReserved) {
+  // Register two extensions.
+  RtpPacketToSend::ExtensionManager extensions;
+  extensions.Register(kRtpExtensionTransmissionTimeOffset,
+                      kTransmissionOffsetExtensionId);
+  extensions.Register(kRtpExtensionAudioLevel, kAudioLevelExtensionId);
+
+  RtpPacketReceived packet(&extensions);
+
+  // Reserve slot for only one of them.
+  EXPECT_TRUE(packet.ReserveExtension<TransmissionOffset>());
+  // Non-registered extension cannot be reserved.
+  EXPECT_FALSE(packet.ReserveExtension<VideoContentTypeExtension>());
+
+  // Only the extension that is both registered and reserved matches
+  // IsExtensionReserved().
+  EXPECT_FALSE(packet.IsExtensionReserved<VideoContentTypeExtension>());
+  EXPECT_FALSE(packet.IsExtensionReserved<AudioLevel>());
+  EXPECT_TRUE(packet.IsExtensionReserved<TransmissionOffset>());
+}
+
 }  // namespace webrtc