diff --git a/CHANGELOG.md b/CHANGELOG.md
index dc1a7954f..4bb318d2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   finance team
 - Added a field to enter the date a grant payment certificate was received to
   the Conversions Receive grant payment certificate task.
+- Script to backfill dates in the Conversions Receive grant payment certificate
+  task
 
 ### Changed
 
diff --git a/app/services/import/grant_certificate_date_importer_service.rb b/app/services/import/grant_certificate_date_importer_service.rb
new file mode 100644
index 000000000..e78df8420
--- /dev/null
+++ b/app/services/import/grant_certificate_date_importer_service.rb
@@ -0,0 +1,27 @@
+require "csv"
+
+class Import::GrantCertificateDateImporterService
+  def call(csv_path)
+    CSV.foreach(csv_path, headers: true, header_converters: :symbol) do |row|
+      urn = row[:urn]
+      next unless urn
+
+      project = Project.find_by(academy_urn: urn.to_i)
+      unless project
+        puts "Unable to find project with academy_urn: #{urn}"
+        next
+      end
+
+      tasks_data = project.tasks_data
+      next unless tasks_data
+
+      date_string = row[:date].to_s
+      date = Date.strptime(date_string, "%d/%m/%Y")
+      tasks_data.receive_grant_payment_certificate_date_received = date
+      tasks_data.save(validate: false)
+      puts "Updated grant payment certificate date for project with academy_urn: #{urn}"
+    rescue Date::Error
+      puts "Date for URN #{urn} is not valid"
+    end
+  end
+end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index ea95a34ea..eac81e763 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -76,6 +76,9 @@ en:
     director_of_child_services_importer:
       import:
         error: You must provide a path, e.g. director_of_child_services:import[path/to/data.csv]
+    grant_payment_certificate_importer:
+      import:
+        error: You must provide a path, e.g. project_data:grant_payment_certificate_dates[path/to/data.csv]
   assignment:
     assign_regional_delivery_officer:
       title: Change regional delivery officer for %{school_name}
diff --git a/lib/tasks/project_tasks/project_data_import.rake b/lib/tasks/project_tasks/project_data_import.rake
new file mode 100644
index 000000000..6687295b5
--- /dev/null
+++ b/lib/tasks/project_tasks/project_data_import.rake
@@ -0,0 +1,10 @@
+namespace :project_data do
+  desc ">> Update dates in the Conversion Grant payment certificate task"
+  task :grant_payment_certificate_dates, [:csv_path] => :environment do |_task, args|
+    abort I18n.t("tasks.grant_payment_certificate_importer.import.error") if args[:csv_path].nil?
+
+    csv_path = Rails.root.join(args[:csv_path])
+
+    Import::GrantCertificateDateImporterService.new.call(csv_path)
+  end
+end
diff --git a/spec/lib/tasks/project_tasks/project_data_import_spec.rb b/spec/lib/tasks/project_tasks/project_data_import_spec.rb
new file mode 100644
index 000000000..5e4750ea3
--- /dev/null
+++ b/spec/lib/tasks/project_tasks/project_data_import_spec.rb
@@ -0,0 +1,22 @@
+require "rails_helper"
+
+RSpec.describe "rake project_data:grant_payment_certificate_dates", type: :task do
+  subject { Rake::Task["project_data:grant_payment_certificate_dates"] }
+
+  let(:csv_path) { "/csv/grant_payment_certificate_dates.csv" }
+
+  before do
+    allow_any_instance_of(Import::GrantCertificateDateImporterService).to receive(:call)
+  end
+
+  it "calls GrantCertificateDateImporterService service with the supplied path" do
+    expect_any_instance_of(Import::GrantCertificateDateImporterService).to receive(:call).with(Pathname.new(csv_path)).once
+
+    subject.invoke(csv_path)
+  end
+
+  it "errors if no path is supplied" do
+    expect { subject.execute }
+      .to raise_error(SystemExit, I18n.t("tasks.grant_payment_certificate_importer.import.error"))
+  end
+end
diff --git a/spec/services/import/grant_certificate_date_importer_service_spec.rb b/spec/services/import/grant_certificate_date_importer_service_spec.rb
new file mode 100644
index 000000000..da73f759c
--- /dev/null
+++ b/spec/services/import/grant_certificate_date_importer_service_spec.rb
@@ -0,0 +1,90 @@
+require "rails_helper"
+
+RSpec.describe Import::GrantCertificateDateImporterService do
+  let(:csv_path) { "/csv/grant_certificate_dates.csv" }
+  let(:date_importer) { Import::GrantCertificateDateImporterService.new }
+  let(:date_csv) do
+    <<~CSV
+      URN,Date
+      149962,09/12/2023
+      150075,17/10/2023
+    CSV
+  end
+
+  before { allow(File).to receive(:open).with(csv_path, any_args).and_return(date_csv) }
+
+  before do
+    mock_all_academies_api_responses
+  end
+
+  describe "#call" do
+    subject(:call_date_importer) { date_importer.call(csv_path) }
+
+    context "when dates are all valid and URNs are all present" do
+      let(:tasks_data_1) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let(:tasks_data_2) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let!(:project_1) { create(:conversion_project, academy_urn: 149962, tasks_data: tasks_data_1) }
+      let!(:project_2) { create(:conversion_project, academy_urn: 150075, tasks_data: tasks_data_2) }
+
+      it "updates all the project tasks_data" do
+        call_date_importer
+
+        expect(project_1.tasks_data.reload.receive_grant_payment_certificate_date_received).to eq(Date.new(2023, 12, 9))
+        expect(project_2.tasks_data.reload.receive_grant_payment_certificate_date_received).to eq(Date.new(2023, 10, 17))
+      end
+    end
+
+    context "when a URN is not valid" do
+      let(:tasks_data_1) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let!(:project_1) { create(:conversion_project, academy_urn: 149962, tasks_data: tasks_data_1) }
+
+      it "updates all other rows" do
+        call_date_importer
+
+        expect(project_1.tasks_data.reload.receive_grant_payment_certificate_date_received).to eq(Date.new(2023, 12, 9))
+      end
+    end
+
+    context "when a date is not valid" do
+      let(:tasks_data_1) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let(:tasks_data_2) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let!(:project_1) { create(:conversion_project, academy_urn: 149962, tasks_data: tasks_data_1) }
+      let!(:project_2) { create(:conversion_project, academy_urn: 150075, tasks_data: tasks_data_2) }
+      let(:date_csv) do
+        <<~CSV
+          URN,Date
+          149962,09/12/2023
+          150075,17/18/2023
+        CSV
+      end
+
+      it "updates all other rows" do
+        call_date_importer
+
+        expect(project_1.tasks_data.reload.receive_grant_payment_certificate_date_received).to eq(Date.new(2023, 12, 9))
+        expect(project_2.tasks_data.reload.receive_grant_payment_certificate_date_received).to be_nil
+      end
+    end
+
+    context "when a date is zero" do
+      let(:tasks_data_1) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let(:tasks_data_2) { create(:conversion_tasks_data, receive_grant_payment_certificate_date_received: nil) }
+      let!(:project_1) { create(:conversion_project, academy_urn: 149962, tasks_data: tasks_data_1) }
+      let!(:project_2) { create(:conversion_project, academy_urn: 150075, tasks_data: tasks_data_2) }
+      let(:date_csv) do
+        <<~CSV
+          URN,Date
+          149962,09/12/2023
+          150075,0
+        CSV
+      end
+
+      it "updates all other rows" do
+        call_date_importer
+
+        expect(project_1.tasks_data.reload.receive_grant_payment_certificate_date_received).to eq(Date.new(2023, 12, 9))
+        expect(project_2.tasks_data.reload.receive_grant_payment_certificate_date_received).to be_nil
+      end
+    end
+  end
+end