diff --git a/db/migrate/20250721111034_add_highest_access_level_to_seat_assignments.rb b/db/migrate/20250721111034_add_highest_access_level_to_seat_assignments.rb
new file mode 100644
index 0000000000000000000000000000000000000000..14d2b087ecb7d31ef3da3006d5e3cffc17c5dd49
--- /dev/null
+++ b/db/migrate/20250721111034_add_highest_access_level_to_seat_assignments.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AddHighestAccessLevelToSeatAssignments < Gitlab::Database::Migration[2.3]
+  milestone '18.3'
+
+  def change
+    add_column :subscription_seat_assignments, :highest_access_level, :integer
+  end
+end
diff --git a/db/schema_migrations/20250721111034 b/db/schema_migrations/20250721111034
new file mode 100644
index 0000000000000000000000000000000000000000..2db2bb9d4873e839bf2836c6cadae81e85dd1253
--- /dev/null
+++ b/db/schema_migrations/20250721111034
@@ -0,0 +1 @@
+2195f874da176acf513bcb52aa7a73c22e37d37364db8130073bd32ad57eb367
\ No newline at end of file
diff --git a/db/structure.sql b/db/structure.sql
index 9fbf0a27e071ceab799c47eae7e9c57205718a75..aa498d58a24a7fb37f7c916f9833473dfa956843 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -24028,7 +24028,8 @@ CREATE TABLE subscription_seat_assignments (
     created_at timestamp with time zone NOT NULL,
     updated_at timestamp with time zone NOT NULL,
     organization_id bigint NOT NULL,
-    seat_type smallint
+    seat_type smallint,
+    highest_access_level integer
 );
 
 CREATE SEQUENCE subscription_seat_assignments_id_seq
diff --git a/ee/app/services/gitlab_subscriptions/members/added_service.rb b/ee/app/services/gitlab_subscriptions/members/added_service.rb
index 1659e5c54b70e4e37740f3178c1b528c3fe3ecbd..0bce23b6e67204858ed54df99724c59e7931cea3 100644
--- a/ee/app/services/gitlab_subscriptions/members/added_service.rb
+++ b/ee/app/services/gitlab_subscriptions/members/added_service.rb
@@ -16,16 +16,20 @@ def execute
         namespace_id = source.root_ancestor.id
         organization_id = source.root_ancestor.organization_id
 
-        recently_added_members_user_ids.each_slice(BATCH_SIZE) do |batch|
-          seat_assignments = batch.map do |user_id|
+        recently_added_members_users.each_batch(of: BATCH_SIZE) do |batch|
+          seat_assignments = batch.map do |group_member|
+            user = group_member.user
+            highest_access_level = user.current_highest_access_level
+
             {
+              highest_access_level: highest_access_level,
               namespace_id: namespace_id,
-              user_id: user_id,
-              organization_id: organization_id
+              organization_id: organization_id,
+              user_id: user.id
             }
           end
 
-          GitlabSubscriptions::SeatAssignment.insert_all(
+          GitlabSubscriptions::SeatAssignment.upsert_all(
             seat_assignments,
             unique_by: [:namespace_id, :user_id]
           )
@@ -38,8 +42,8 @@ def execute
 
       attr_reader :source, :invited_user_ids
 
-      def recently_added_members_user_ids
-        source.members.connected_to_user.including_user_ids(invited_user_ids).pluck_user_ids
+      def recently_added_members_users
+        source.members.connected_to_user.including_user_ids(invited_user_ids).including_user
       end
     end
   end
diff --git a/ee/spec/services/gitlab_subscriptions/members/added_service_spec.rb b/ee/spec/services/gitlab_subscriptions/members/added_service_spec.rb
index 7876eaedfdab90b0ab0777c05e1f6b94ef415df6..954a4f2fc420b48d8a064deeb6d02c203a92fc24 100644
--- a/ee/spec/services/gitlab_subscriptions/members/added_service_spec.rb
+++ b/ee/spec/services/gitlab_subscriptions/members/added_service_spec.rb
@@ -15,29 +15,54 @@
     describe 'with valid params' do
       let(:source) { create(:group, parent: namespace) }
 
-      it 'create a new seat assignment record' do
+      before do
         source.add_developer(user)
+      end
 
+      it 'create a new seat assignment record' do
         expect do
           expect(execute).to be_success
         end.to change { GitlabSubscriptions::SeatAssignment.where(user: user, namespace: namespace).count }
           .by(1)
       end
 
-      it 'does not create new seat_assignment record, if one already exists' do
-        create(:gitlab_subscription_seat_assignment, namespace: namespace, user: user)
+      it "saves user's highest access level" do
+        create(:group, parent: namespace).add_maintainer(user)
 
-        expect do
-          expect(execute).to be_success
-        end.not_to change { GitlabSubscriptions::SeatAssignment.count }
+        execute
+
+        expect(GitlabSubscriptions::SeatAssignment.last.highest_access_level).to eq Gitlab::Access::MAINTAINER
+      end
+
+      context 'with existing seat assignment record' do
+        before do
+          create(
+            :gitlab_subscription_seat_assignment,
+            namespace: namespace,
+            user: user,
+            highest_access_level: Gitlab::Access::DEVELOPER
+          )
+        end
+
+        it 'does not create new seat_assignment record' do
+          expect do
+            expect(execute).to be_success
+          end.not_to change { GitlabSubscriptions::SeatAssignment.count }
+        end
+
+        it 'updates seat assigment record' do
+          create(:group, parent: namespace).add_maintainer(user)
+
+          expect { execute }
+            .to change { GitlabSubscriptions::SeatAssignment.last.highest_access_level }
+            .from(Gitlab::Access::DEVELOPER).to(Gitlab::Access::MAINTAINER)
+        end
       end
 
       context "when source is of type 'Project'" do
         let(:source) { build(:project, namespace: namespace) }
 
         it 'creates new seat assignment record' do
-          source.add_developer(user)
-
           expect do
             expect(execute).to be_success
           end.to change { GitlabSubscriptions::SeatAssignment.where(user: user, namespace: namespace).count }.by(1)