diff --git a/lib/tasks/temp/change_beis_site_orgs.rake b/lib/tasks/temp/change_beis_site_orgs.rake
new file mode 100644
index 000000000..59419f353
--- /dev/null
+++ b/lib/tasks/temp/change_beis_site_orgs.rake
@@ -0,0 +1,72 @@
+namespace :temp do
+  desc "Change the organisations for a select group of formerly BEIS sites"
+  task modify_beis_orgs: :environment do
+    desnz_hosts = [
+      "archive.bis.gov.uk",
+      "blog.decc.gov.uk",
+      "blogs.bis.gov.uk",
+      "ceo.decc.gov.uk",
+      "choices.bis.gov.uk",
+      "chp.decc.gov.uk",
+      "chpqa.decc.gov.uk",
+      "consultations.bis.gov.uk",
+      "conversation.bis.gov.uk",
+      "corwm.decc.gov.uk",
+      "digital.bis.gov.uk",
+      "discuss.bis.gov.uk",
+      "diversity.bis.gov.uk",
+      "etl.decc.gov.uk",
+      "forms.bis.gov.uk",
+      "gdcashback.decc.gov.uk",
+      "iacl.bis.gov.uk",
+      "interactive.bis.gov.uk",
+      "library.bis.gov.uk",
+      "mrws.decc.gov.uk",
+      "my2050.decc.gov.uk",
+      "news.bis.gov.uk",
+      "nlss.bis.gov.uk",
+      "og.decc.gov.uk",
+      "publications.bis.gov.uk",
+      "publicsectorinnovation.bis.gov.uk",
+      "rct.bis.gov.uk",
+      "rdna-tool.bis.gov.uk",
+      "renewableconsultation.bis.gov.uk",
+      "restats.decc.gov.uk",
+      "sandbox.bis.gov.uk",
+      "search.bis.gov.uk",
+      "stats.bis.gov.uk",
+      "sts.bis.gov.uk",
+      "talk.bis.gov.uk",
+      "tools.decc.gov.uk",
+      "vapp.bis.gov.uk",
+      "www.beis.gov.uk",
+      "www.berr.gov.uk",
+      "www.bis.gov.uk",
+      "www.decc.gov.uk",
+      "www.dti.gov.uk",
+      "www.mentorme.bis.gov.uk",
+      "www.offshore-sea.org.uk",
+      "www.simpleenergyadvice.org.uk",
+    ]
+    dsit_hosts = [
+      "hsctoolkit.bis.gov.uk",
+      "hsctraininggateway.bis.gov.uk",
+      "scienceandsociety.bis.gov.uk",
+      "www.aebc.gov.uk",
+      "www.dius.gov.uk",
+      "www.dsit.gov.uk",
+      "www.sciencewise-erc.org.uk",
+      "www.securityhealthcheck.bis.gov.uk",
+      "www.sigmascan.org",
+    ]
+
+    desnz_sites = Site.all.select { |site| desnz_hosts.include?(site.default_host.hostname) }
+    dsit_sites = Site.all.select { |site| dsit_hosts.include?(site.default_host.hostname) }
+
+    dsit = Organisation.find_by(whitehall_slug: "department-for-science-innovation-and-technology")
+    desnz = Organisation.find_by(whitehall_slug: "department-for-energy-security-and-net-zero")
+
+    desnz_sites.each { |site| site.update(organisation_id: desnz.id) }
+    dsit_sites.each { |site| site.update(organisation_id: dsit.id) }
+  end
+end