diff --git a/app/models/lettings_log.rb b/app/models/lettings_log.rb
index d193fc70c..8eadd4e54 100644
--- a/app/models/lettings_log.rb
+++ b/app/models/lettings_log.rb
@@ -690,6 +690,16 @@ class LettingsLog < Log
     address_line1_input.present? && postcode_full_input.present?
   end
 
+  def process_postcode_changes!
+    self.postcode_full = upcase_and_remove_whitespace(postcode_full)
+    return if postcode_full.blank?
+
+    self.postcode_known = 1
+    inferred_la = get_inferred_la(postcode_full)
+    self.is_la_inferred = inferred_la.present?
+    self.la = inferred_la if inferred_la.present?
+  end
+
 private
 
   def reset_invalid_unresolved_log_fields!
@@ -744,16 +754,6 @@ private
     collection_start_year >= 2022 && !is_fixed_term_tenancy?
   end
 
-  def process_postcode_changes!
-    self.postcode_full = upcase_and_remove_whitespace(postcode_full)
-    return if postcode_full.blank?
-
-    self.postcode_known = 1
-    inferred_la = get_inferred_la(postcode_full)
-    self.is_la_inferred = inferred_la.present?
-    self.la = inferred_la if inferred_la.present?
-  end
-
   def process_previous_postcode_changes!
     self.ppostcode_full = upcase_and_remove_whitespace(ppostcode_full)
     return if ppostcode_full.blank?
diff --git a/lib/tasks/reinfer_local_authority.rake b/lib/tasks/reinfer_local_authority.rake
new file mode 100644
index 000000000..a17d7eed6
--- /dev/null
+++ b/lib/tasks/reinfer_local_authority.rake
@@ -0,0 +1,14 @@
+desc "Reinfers LA from postcode where it's missing"
+task reinfer_local_authority: :environment do
+  LettingsLog.filter_by_year(2023).where(needstype: 1, la: nil).where.not(postcode_full: nil).find_each do |log|
+    log.process_postcode_changes!
+
+    Rails.logger.info "Invalid lettings log: #{log.id}" unless log.save
+  end
+
+  SalesLog.filter_by_year(2023).where(la: nil).where.not(postcode_full: nil).find_each do |log|
+    log.process_postcode_changes!
+
+    Rails.logger.info "Invalid sales log: #{log.id}" unless log.save
+  end
+end
diff --git a/spec/lib/tasks/reinfer_local_authority_spec.rb b/spec/lib/tasks/reinfer_local_authority_spec.rb
new file mode 100644
index 000000000..c92d227dc
--- /dev/null
+++ b/spec/lib/tasks/reinfer_local_authority_spec.rb
@@ -0,0 +1,88 @@
+require "rails_helper"
+require "rake"
+
+RSpec.describe "reinfer_local_authority" do
+  describe ":reinfer_local_authority", type: :task do
+    subject(:task) { Rake::Task["reinfer_local_authority"] }
+
+    before do
+      Rake.application.rake_require("tasks/reinfer_local_authority")
+      Rake::Task.define_task(:environment)
+      task.reenable
+    end
+
+    context "when the rake task is run" do
+      context "and there is a general needs type lettings log with postcode and without LA" do
+        let(:log) { create(:lettings_log, :completed, postcode_full: "AA1 1AA", status: "completed", startdate: Time.zone.local(2023, 4, 1)) }
+
+        it "updates the la if it can be inferred" do
+          log.la = nil
+          log.save!(validate: false)
+          task.invoke
+
+          log.reload
+          expect(log.la).to eq("E09000033")
+          expect(log.status).to eq("completed")
+        end
+
+        it "does not update the la if it cannot be inferred and sets status to in_progress" do
+          log.la = nil
+          log.postcode_full = "B11AB"
+          log.save!(validate: false)
+          task.invoke
+
+          log.reload
+          expect(log.la).to be_nil
+          expect(log.status).to eq("in_progress")
+        end
+      end
+
+      context "and the lettings log has a validation error" do
+        let(:log) { build(:lettings_log, :completed, postcode_full: "some fake postcode", la: nil, status: "completed", startdate: Time.zone.local(2023, 4, 1)) }
+
+        it "logs invalid log ID" do
+          log.save!(validate: false)
+          expect(Rails.logger).to receive(:info).with("Invalid lettings log: #{log.id}")
+
+          task.invoke
+        end
+      end
+
+      context "and there is a sales log with postcode and without LA" do
+        let(:log) { create(:sales_log, :completed, postcode_full: "AA1 1AA", status: "completed", saledate: Time.zone.local(2023, 4, 1)) }
+
+        it "updates the la if it can be inferred" do
+          log.la = nil
+          log.save!(validate: false)
+          task.invoke
+
+          log.reload
+          expect(log.la).to eq("E09000033")
+          expect(log.status).to eq("completed")
+        end
+
+        it "does not update the la if it cannot be inferred and sets status to in_progress" do
+          log.la = nil
+          log.postcode_full = "B11AB"
+          log.save!(validate: false)
+          task.invoke
+
+          log.reload
+          expect(log.la).to be_nil
+          expect(log.status).to eq("in_progress")
+        end
+      end
+
+      context "and the sales log has a validation error" do
+        let(:log) { build(:sales_log, :completed, postcode_full: "some fake postcode", la: nil, status: "completed", saledate: Time.zone.local(2023, 4, 1)) }
+
+        it "logs invalid log ID" do
+          log.save!(validate: false)
+          expect(Rails.logger).to receive(:info).with("Invalid sales log: #{log.id}")
+
+          task.invoke
+        end
+      end
+    end
+  end
+end