diff --git a/lib/tasks/set_sales_managing_organisation.rake b/lib/tasks/set_sales_managing_organisation.rake
new file mode 100644
index 000000000..85e2ced22
--- /dev/null
+++ b/lib/tasks/set_sales_managing_organisation.rake
@@ -0,0 +1,4 @@
+desc "Set sales managing organisation id to owning organisation id"
+task set_sales_managing_organisation: :environment do
+  SalesLog.where.not(owning_organisation_id: nil).update_all("managing_organisation_id = owning_organisation_id")
+end
diff --git a/spec/lib/tasks/set_sales_managing_organisation_spec.rb b/spec/lib/tasks/set_sales_managing_organisation_spec.rb
new file mode 100644
index 000000000..c8e304d9f
--- /dev/null
+++ b/spec/lib/tasks/set_sales_managing_organisation_spec.rb
@@ -0,0 +1,48 @@
+require "rails_helper"
+require "rake"
+
+RSpec.describe "set_sales_managing_organisation" do
+  describe ":set_sales_managing_organisation", type: :task do
+    subject(:task) { Rake::Task["set_sales_managing_organisation"] }
+
+    before do
+      Rake.application.rake_require("tasks/set_sales_managing_organisation")
+      Rake::Task.define_task(:environment)
+      task.reenable
+    end
+
+    context "when the rake task is run" do
+      let!(:sales_log) { create(:sales_log, :completed, managing_organisation_id: nil) }
+
+      it "updates sales log managing_organisation_id with owning_organisation_id" do
+        expect(sales_log.managing_organisation_id).to eq(nil)
+        expect(sales_log.status).to eq("completed")
+        task.invoke
+        sales_log.reload
+        expect(sales_log.managing_organisation_id).to eq(sales_log.owning_organisation_id)
+        expect(sales_log.status).to eq("completed")
+      end
+
+      it "does not update sales log managing_organisation_id if owning_organisation_id is nil" do
+        sales_log.update!(owning_organisation_id: nil)
+        expect(sales_log.status).to eq("in_progress")
+        expect(sales_log.managing_organisation_id).to eq(nil)
+        task.invoke
+        sales_log.reload
+        expect(sales_log.managing_organisation_id).to eq(nil)
+        expect(sales_log.status).to eq("in_progress")
+      end
+
+      it "skips validations" do
+        sales_log.saledate = Time.zone.local(2021, 3, 3)
+        sales_log.save!(validate: false)
+        expect(sales_log.managing_organisation_id).to eq(nil)
+        expect(sales_log.status).to eq("in_progress")
+        task.invoke
+        sales_log.reload
+        expect(sales_log.managing_organisation_id).to eq(sales_log.owning_organisation_id)
+        expect(sales_log.status).to eq("in_progress")
+      end
+    end
+  end
+end