diff --git a/group_vars/matrix_servers b/group_vars/matrix_servers
index b76b38fff..d222ded5e 100755
--- a/group_vars/matrix_servers
+++ b/group_vars/matrix_servers
@@ -850,7 +850,7 @@ devture_systemd_service_manager_services_list_auto: |
     ([{
       'name': 'matrix-synapse-s3-storage-provider-migrate.timer',
       'priority': 5000,
-      'restart_necessary': true,
+      'restart_necessary': (matrix_synapse_s3_storage_provider_restart_necessary | bool),
       'groups': ['matrix'],
     }] if (matrix_synapse_enabled and matrix_synapse_ext_synapse_s3_storage_provider_enabled) else [])
     +
diff --git a/roles/custom/matrix-synapse/defaults/main.yml b/roles/custom/matrix-synapse/defaults/main.yml
index 4bdf7571d..0a240a81f 100644
--- a/roles/custom/matrix-synapse/defaults/main.yml
+++ b/roles/custom/matrix-synapse/defaults/main.yml
@@ -125,6 +125,17 @@ matrix_synapse_ext_s3_storage_provider_data_path: "{{ matrix_synapse_ext_s3_stor
 # extra arguments to pass to s3-storage-provider script when starting Synapse container
 matrix_synapse_ext_s3_storage_provider_container_arguments: []
 
+# matrix_synapse_s3_storage_provider_restart_necessary controls whether the
+# s3-storage-provider migrate timer will be restarted (when true) or merely
+# started (when false) by the systemd service manager role (when conditional
+# restart is enabled).
+#
+# This value is automatically computed during installation based on whether
+# any configuration files or the systemd service/timer files changed.
+# The default of `false` means "no restart needed" — appropriate when the role's
+# installation tasks haven't run (e.g., due to --tags skipping them).
+matrix_synapse_s3_storage_provider_restart_necessary: false
+
 matrix_synapse_container_client_api_port: 8008
 
 # Controls the `x_forwarded` setting for the "Insecure HTTP listener (Client API)".
diff --git a/roles/custom/matrix-synapse/tasks/ext/s3-storage-provider/setup_install.yml b/roles/custom/matrix-synapse/tasks/ext/s3-storage-provider/setup_install.yml
index cd900b306..4fef06601 100644
--- a/roles/custom/matrix-synapse/tasks/ext/s3-storage-provider/setup_install.yml
+++ b/roles/custom/matrix-synapse/tasks/ext/s3-storage-provider/setup_install.yml
@@ -27,12 +27,14 @@
     src: "{{ role_path }}/templates/synapse/ext/s3-storage-provider/env.j2"
     dest: "{{ matrix_synapse_ext_s3_storage_provider_base_path }}/env"
     mode: '0640'
+  register: matrix_synapse_s3_storage_provider_env_result
 
 - name: Ensure s3-storage-provider database.yaml file installed
   ansible.builtin.template:
     src: "{{ role_path }}/templates/synapse/ext/s3-storage-provider/database.yaml.j2"
     dest: "{{ matrix_synapse_ext_s3_storage_provider_data_path }}/database.yaml"
     mode: '0640'
+  register: matrix_synapse_s3_storage_provider_database_config_result
 
 - name: Ensure s3-storage-provider scripts installed
   ansible.builtin.template:
@@ -42,6 +44,7 @@
   with_items:
     - shell
     - migrate
+  register: matrix_synapse_s3_storage_provider_scripts_result
 
 - name: Ensure matrix-synapse-s3-storage-provider-migrate.service and timer are installed
   ansible.builtin.template:
@@ -52,3 +55,13 @@
     - matrix-synapse-s3-storage-provider-migrate.service
     - matrix-synapse-s3-storage-provider-migrate.timer
   register: matrix_synapse_s3_storage_provider_systemd_service_result
+
+- name: Determine whether s3-storage-provider migrate timer needs a restart
+  ansible.builtin.set_fact:
+    matrix_synapse_s3_storage_provider_restart_necessary: >-
+      {{
+        matrix_synapse_s3_storage_provider_env_result.changed | default(false)
+        or matrix_synapse_s3_storage_provider_database_config_result.changed | default(false)
+        or matrix_synapse_s3_storage_provider_scripts_result.changed | default(false)
+        or matrix_synapse_s3_storage_provider_systemd_service_result.changed | default(false)
+      }}