diff --git a/changelog.d/6044.feature b/changelog.d/6044.feature
new file mode 100644
index 000000000000..7dc05d4845fe
--- /dev/null
+++ b/changelog.d/6044.feature
@@ -0,0 +1 @@
+Add an unstable feature flag for separate add/bind 3pid APIs.
\ No newline at end of file
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index fdab0ddb42b3..1044ae7b4e9f 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -63,6 +63,8 @@ def on_GET(self, request):
                     # verification itself, there is no need to ask the user for `id_server` to
                     # be supplied.
                     "m.require_identity_server": False,
+                    # as per MSC2290
+                    "m.separate_add_and_bind": True,
                 },
             },
         )