diff --git a/pkg/apis/core/annotation_key_constants.go b/pkg/apis/core/annotation_key_constants.go
index a1e6daae496..bef73c0db0b 100644
--- a/pkg/apis/core/annotation_key_constants.go
+++ b/pkg/apis/core/annotation_key_constants.go
@@ -82,4 +82,23 @@ const (
 	//
 	// Not all cloud providers support this annotation, though AWS & GCE do.
 	AnnotationLoadBalancerSourceRangesKey = "service.beta.kubernetes.io/load-balancer-source-ranges"
+
+	// EndpointsLastChangeTriggerTime is the annotation key, set for endpoints objects, that
+	// represents the timestamp (stored as RFC 3339 date-time string, e.g. '2018-10-22T19:32:52.1Z')
+	// of the last change, of some Pod or Service object, that triggered the endpoints object change.
+	// In other words, if a Pod / Service changed at time T0, that change was observed by endpoints
+	// controller at T1, and the Endpoints object was changed at T2, the
+	// EndpointsLastChangeTriggerTime would be set to T0.
+	//
+	// The "endpoints change trigger" here means any Pod or Service change that resulted in the
+	// Endpoints object change.
+	//
+	// Given the definition of the "endpoints change trigger", please note that this annotation will
+	// be set ONLY for endpoints object changes triggered by either Pod or Service change. If the
+	// Endpoints object changes due to other reasons, this annotation won't be set (or updated if it's
+	// already set).
+	//
+	// This annotation will be used to compute the in-cluster network programming latency SLI, see
+	// https://github.com/kubernetes/community/blob/master/sig-scalability/slos/network_programming_latency.md
+	EndpointsLastChangeTriggerTime = "endpoints.kubernetes.io/last-change-trigger-time"
 )
diff --git a/staging/src/k8s.io/api/core/v1/annotation_key_constants.go b/staging/src/k8s.io/api/core/v1/annotation_key_constants.go
index 16a0cfced13..2c72ec2df2d 100644
--- a/staging/src/k8s.io/api/core/v1/annotation_key_constants.go
+++ b/staging/src/k8s.io/api/core/v1/annotation_key_constants.go
@@ -78,4 +78,23 @@ const (
 	//
 	// Not all cloud providers support this annotation, though AWS & GCE do.
 	AnnotationLoadBalancerSourceRangesKey = "service.beta.kubernetes.io/load-balancer-source-ranges"
+
+	// EndpointsLastChangeTriggerTime is the annotation key, set for endpoints objects, that
+	// represents the timestamp (stored as RFC 3339 date-time string, e.g. '2018-10-22T19:32:52.1Z')
+	// of the last change, of some Pod or Service object, that triggered the endpoints object change.
+	// In other words, if a Pod / Service changed at time T0, that change was observed by endpoints
+	// controller at T1, and the Endpoints object was changed at T2, the
+	// EndpointsLastChangeTriggerTime would be set to T0.
+	//
+	// The "endpoints change trigger" here means any Pod or Service change that resulted in the
+	// Endpoints object change.
+	//
+	// Given the definition of the "endpoints change trigger", please note that this annotation will
+	// be set ONLY for endpoints object changes triggered by either Pod or Service change. If the
+	// Endpoints object changes due to other reasons, this annotation won't be set (or updated if it's
+	// already set).
+	//
+	// This annotation will be used to compute the in-cluster network programming latency SLI, see
+	// https://github.com/kubernetes/community/blob/master/sig-scalability/slos/network_programming_latency.md
+	EndpointsLastChangeTriggerTime = "endpoints.kubernetes.io/last-change-trigger-time"
 )