diff --git a/watchtower/wtwire/create_session_reply.go b/watchtower/wtwire/create_session_reply.go
new file mode 100644
index 00000000..b1224cb8
--- /dev/null
+++ b/watchtower/wtwire/create_session_reply.go
@@ -0,0 +1,91 @@
+package wtwire
+
+import "io"
+
+// CreateSessionCode is an error code returned by a watchtower in response to a
+// CreateSession message. The code directs the client in interpreting the payload
+// in the reply.
+type CreateSessionCode = ErrorCode
+
+const (
+	// CreateSessionCodeAlreadyExists is returned when a session is already
+	// active for the public key used to connect to the watchtower. The
+	// response includes the serialized reward address in case the original
+	// reply was never received and/or processed by the client.
+	CreateSessionCodeAlreadyExists CreateSessionCode = 60
+
+	// CreateSessionCodeRejectRejectMaxUpdates the tower rejected the maximum
+	// number of state updates proposed by the client.
+	CreateSessionCodeRejectRejectMaxUpdates CreateSessionCode = 61
+
+	// CreateSessionCodeRejectRewardRate the tower rejected the reward rate
+	// proposed by the client.
+	CreateSessionCodeRejectRewardRate CreateSessionCode = 62
+
+	// CreateSessionCodeRejectSweepFeeRate the tower rejected the sweep fee
+	// rate proposed by the client.
+	CreateSessionCodeRejectSweepFeeRate CreateSessionCode = 63
+)
+
+// MaxCreateSessionReplyDataLength is the maximum size of the Data payload
+// returned in a CreateSessionReply message. This does not include the length of
+// the Data field, which is a varint up to 3 bytes in size.
+const MaxCreateSessionReplyDataLength = 1024
+
+// CreateSessionReply is a message sent from watchtower to client in response to a
+// CreateSession message, and signals either an acceptance or rejection of the
+// proposed session parameters.
+type CreateSessionReply struct {
+	// Code will be non-zero if the watchtower rejected the session init.
+	Code CreateSessionCode
+
+	// Data is a byte slice returned the caller of the message, and is to be
+	// interpreted according to the error Code. When the response is
+	// CreateSessionCodeOK, data encodes the reward address to be included in
+	// any sweep transactions if the reward is not dusty. Otherwise, it may
+	// encode the watchtowers configured parameters for any policy
+	// rejections.
+	Data []byte
+}
+
+// A compile time check to ensure CreateSessionReply implements the wtwire.Message
+// interface.
+var _ Message = (*CreateSessionReply)(nil)
+
+// Decode deserializes a serialized CreateSessionReply message stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSessionReply) Decode(r io.Reader, pver uint32) error {
+	return ReadElements(r,
+		&m.Code,
+		&m.Data,
+	)
+}
+
+// Encode serializes the target CreateSessionReply into the passed io.Writer
+// observing the protocol version specified.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSessionReply) Encode(w io.Writer, pver uint32) error {
+	return WriteElements(w,
+		m.Code,
+		m.Data,
+	)
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSessionReply) MsgType() MessageType {
+	return MsgCreateSessionReply
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a CreateSessionReply
+// complete message observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSessionReply) MaxPayloadLength(uint32) uint32 {
+	return 2 + 3 + MaxCreateSessionReplyDataLength
+}