diff --git a/lib/tasks/set_renttype_detail.rake b/lib/tasks/set_renttype_detail.rake
new file mode 100644
index 000000000..76dd178b1
--- /dev/null
+++ b/lib/tasks/set_renttype_detail.rake
@@ -0,0 +1,9 @@
+desc "Set lettings renttype_detail depending on rent_type"
+task set_renttype_detail: :environment do
+  LettingsLog.where(rent_type: 0).update_all(renttype_detail: 1)
+  LettingsLog.where(rent_type: 1).update_all(renttype_detail: 2)
+  LettingsLog.where(rent_type: 2).update_all(renttype_detail: 3)
+  LettingsLog.where(rent_type: 3).update_all(renttype_detail: 4)
+  LettingsLog.where(rent_type: 4).update_all(renttype_detail: 5)
+  LettingsLog.where(rent_type: 5).update_all(renttype_detail: 6)
+end
diff --git a/spec/lib/tasks/set_renttype_detail_spec.rb b/spec/lib/tasks/set_renttype_detail_spec.rb
new file mode 100644
index 000000000..c9f972d0f
--- /dev/null
+++ b/spec/lib/tasks/set_renttype_detail_spec.rb
@@ -0,0 +1,98 @@
+require "rails_helper"
+require "rake"
+
+RSpec.describe "set_renttype_detail" do
+  describe ":set_renttype_detail", type: :task do
+    subject(:task) { Rake::Task["set_renttype_detail"] }
+
+    before do
+      Rake.application.rake_require("tasks/set_renttype_detail")
+      Rake::Task.define_task(:environment)
+      task.reenable
+    end
+
+    context "when the rake task is run and rent_type is 0" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 0) }
+
+      it "sets lettings log renttype_detail to 1" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(1)
+      end
+    end
+
+    context "when the rake task is run and rent_type is 1" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 1) }
+
+      it "sets lettings log renttype_detail to 2" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(2)
+      end
+    end
+
+    context "when the rake task is run and rent_type is 2" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 2) }
+
+      it "sets lettings log renttype_detail to 3" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(3)
+      end
+    end
+
+    context "when the rake task is run and rent_type is 3" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 3) }
+
+      it "sets lettings log renttype_detail to 4" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(4)
+      end
+    end
+
+    context "when the rake task is run and rent_type is 4" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 4) }
+
+      it "sets lettings log renttype_detail to 5" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(5)
+      end
+    end
+
+    context "when the rake task is run and rent_type is 5" do
+      let!(:lettings_log) { create(:lettings_log, :completed, rent_type: 5, irproduct_other: "sum") }
+
+      it "sets lettings log renttype_detail to 6" do
+        expect(lettings_log.renttype_detail).to eq(nil)
+        expected_updated_at = lettings_log.updated_at
+        task.invoke
+        lettings_log.reload
+        expect(lettings_log.values_updated_at).to eq(nil)
+        expect(lettings_log.updated_at).to eq(expected_updated_at)
+        expect(lettings_log.renttype_detail).to eq(6)
+      end
+    end
+  end
+end