diff --git a/mercurial/obsutil.py b/mercurial/obsutil.py
--- a/mercurial/obsutil.py
+++ b/mercurial/obsutil.py
@@ -310,6 +310,7 @@ EFFECTFLAGFIELD = "ef1"
 
 DESCCHANGED = 1 << 0 # action changed the description
 USERCHANGED = 1 << 4 # the user changed
+DATECHANGED = 1 << 5 # the date changed
 
 def geteffectflag(relation):
     """ From an obs-marker relation, compute what changed between the
@@ -328,6 +329,10 @@ def geteffectflag(relation):
         if changectx.user() != source.user():
             effects |= USERCHANGED
 
+        # Check if date has changed
+        if changectx.date() != source.date():
+            effects |= DATECHANGED
+
     return effects
 
 def getobsoleted(repo, tr):
diff --git a/tests/test-obsmarkers-effectflag.t b/tests/test-obsmarkers-effectflag.t
--- a/tests/test-obsmarkers-effectflag.t
+++ b/tests/test-obsmarkers-effectflag.t
@@ -51,7 +51,7 @@ amend touching the date only
 check result
 
   $ hg debugobsolete --rev .
-  2ef0680ff45038ac28c9f1ff3644341f54487280 4dd84345082e9e5291c2e6b3f335bbf8bf389378 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '0', 'operation': 'amend', 'user': 'test'}
+  2ef0680ff45038ac28c9f1ff3644341f54487280 4dd84345082e9e5291c2e6b3f335bbf8bf389378 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '32', 'operation': 'amend', 'user': 'test'}
 
 amend touching the branch only
 ----------------------------
@@ -106,7 +106,7 @@ amend with multiple effect (desc and met
 check result
 
   $ hg debugobsolete --rev .
-  fad47e5bd78e6aa4db1b5a0a1751bc12563655ff a94e0fd5f1c81d969381a76eb0d37ce499a44fae 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '17', 'operation': 'amend', 'user': 'test'}
+  fad47e5bd78e6aa4db1b5a0a1751bc12563655ff a94e0fd5f1c81d969381a76eb0d37ce499a44fae 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '49', 'operation': 'amend', 'user': 'test'}
 
 rebase not touching the diff
 ----------------------------