diff --git a/app/models/reports/applications.rb b/app/models/reports/applications.rb
index 1b8d1927..e9e5bbe5 100644
--- a/app/models/reports/applications.rb
+++ b/app/models/reports/applications.rb
@@ -1,6 +1,6 @@
 module Reports
   class Applications < Base
-    def csv
+    def generate
       CSV.generate do |csv|
         csv << header
         rows.find_each(batch_size: 50) { |row| csv << columns(row) }
diff --git a/app/models/reports/base.rb b/app/models/reports/base.rb
index 70fa021b..f2949099 100644
--- a/app/models/reports/base.rb
+++ b/app/models/reports/base.rb
@@ -7,13 +7,23 @@ def initialize(**kwargs)
 
     attr_reader :name, :kwargs
 
+    class << self
+      def file_ext(value)
+        @file_ext = value
+      end
+
+      def get_file_ext
+        @file_ext || "csv"
+      end
+    end
+
     def filename
       current_time = Time.zone.now.strftime("%Y%m%d-%H%M%S")
 
-      "#{name}-#{current_time}.csv"
+      "#{name}-#{current_time}.#{self.class.get_file_ext}"
     end
 
-    def csv; end
+    def generate; end
 
     def post_generation_hook; end
   end
diff --git a/app/models/reports/payroll.rb b/app/models/reports/payroll.rb
index 630be075..c1b35d38 100644
--- a/app/models/reports/payroll.rb
+++ b/app/models/reports/payroll.rb
@@ -2,7 +2,7 @@
 
 module Reports
   class Payroll < Base
-    def csv
+    def generate
       CSV.generate do |csv|
         csv << header
         rows.each { |row| csv << row }
diff --git a/app/models/reports/qa_report.rb b/app/models/reports/qa_report.rb
index 9f6871cb..60a04336 100644
--- a/app/models/reports/qa_report.rb
+++ b/app/models/reports/qa_report.rb
@@ -5,7 +5,7 @@ def initialize(...)
       @name = [@name, status].join("-")
     end
 
-    def csv
+    def generate
       CSV.generate do |csv|
         csv << header
         rows.each { |row| csv << row }
diff --git a/app/models/reports/standing_data.rb b/app/models/reports/standing_data.rb
index 0cf68e6e..c4a90c6b 100644
--- a/app/models/reports/standing_data.rb
+++ b/app/models/reports/standing_data.rb
@@ -2,7 +2,7 @@
 
 module Reports
   class StandingData < Base
-    def csv
+    def generate
       CSV.generate do |csv|
         csv << header
         rows.each { |row| csv << row }
diff --git a/app/services/report.rb b/app/services/report.rb
index ff1ae156..dcce92ea 100644
--- a/app/services/report.rb
+++ b/app/services/report.rb
@@ -26,7 +26,7 @@ def initialize(report_id, **kwargs)
   delegate :post_generation_hook, to: :report
 
   def data
-    @data ||= report.csv
+    @data ||= report.generate
   end
 
 private
diff --git a/spec/features/admin_console/reports_spec.rb b/spec/features/admin_console/reports_spec.rb
index 2db39a78..55a2dea5 100644
--- a/spec/features/admin_console/reports_spec.rb
+++ b/spec/features/admin_console/reports_spec.rb
@@ -54,7 +54,7 @@ def then_the_standing_data_csv_report_is_downloaded
   end
 
   def then_the_home_office_csv_report_is_downloaded
-    expect(page.response_headers["Content-Type"]).to match(/text\/csv/)
+    expect(page.response_headers["Content-Type"]).to match(/application\/vnd.openxmlformats-officedocument.spreadsheetml.sheet/)
     expect(page.response_headers["Content-Disposition"]).to include "attachment"
     expect(page.response_headers["Content-Disposition"]).to match(/filename="reports-home-office.*/)
   end
diff --git a/spec/models/reports/applications_spec.rb b/spec/models/reports/applications_spec.rb
index a327be5a..5ab48214 100644
--- a/spec/models/reports/applications_spec.rb
+++ b/spec/models/reports/applications_spec.rb
@@ -66,17 +66,17 @@ module Reports
           ].join(",")
         end
 
-        it { expect(report.csv).to include(header) }
+        it { expect(report.generate).to include(header) }
       end
 
       context "returns all applications" do
-        it { expect(report.csv).to include(application.urn) }
-        it { expect(report.csv).to include(initial.urn) }
-        it { expect(report.csv).to include(home_office.urn) }
-        it { expect(report.csv).to include(school.urn) }
-        it { expect(report.csv).to include(banking.urn) }
-        it { expect(report.csv).to include(paid.urn) }
-        it { expect(report.csv).to include(rejected.urn) }
+        it { expect(report.generate).to include(application.urn) }
+        it { expect(report.generate).to include(initial.urn) }
+        it { expect(report.generate).to include(home_office.urn) }
+        it { expect(report.generate).to include(school.urn) }
+        it { expect(report.generate).to include(banking.urn) }
+        it { expect(report.generate).to include(paid.urn) }
+        it { expect(report.generate).to include(rejected.urn) }
       end
     end
   end
diff --git a/spec/models/reports/payroll_spec.rb b/spec/models/reports/payroll_spec.rb
index 59d1946b..559c6918 100644
--- a/spec/models/reports/payroll_spec.rb
+++ b/spec/models/reports/payroll_spec.rb
@@ -21,26 +21,26 @@ module Reports
       end
     end
 
-    describe "#csv" do
+    describe "#generate" do
       let(:progress) { build(:application_progress, banking_approval_completed_at: Time.zone.now) }
 
       it "returns applicants who have banking details approved" do
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).to include(app.applicant.family_name)
+        expect(report.generate).to include(app.applicant.family_name)
       end
 
       it "does not return applicants who have not the bankind details approved" do
         progress.banking_approval_completed_at = nil
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).not_to include(app.urn)
+        expect(report.generate).not_to include(app.urn)
       end
 
       it "returns the data in CSV format" do
         application = create(:application, application_progress: progress)
 
-        expect(report.csv).to include([
+        expect(report.generate).to include([
           "", # No.
           "Prof", # TITLE
           application.applicant.given_name, # FORENAME
@@ -116,12 +116,12 @@ module Reports
           RIGHT_TO_WORK_CONFIRM_STATUS
         ].join(",")
 
-        expect(report.csv).to include(expected_header)
+        expect(report.generate).to include(expected_header)
       end
 
       context "includes applications from the csv before invoking `post_generation_hook`" do
         let(:app) { create(:application, application_progress: progress) }
-        let(:csv) { report.csv }
+        let(:csv) { report.generate }
 
         before { app }
 
diff --git a/spec/models/reports/qa_report_spec.rb b/spec/models/reports/qa_report_spec.rb
index 1fd0a83f..8385354e 100644
--- a/spec/models/reports/qa_report_spec.rb
+++ b/spec/models/reports/qa_report_spec.rb
@@ -25,7 +25,7 @@ module Reports
         it "returns the data in CSV format" do
           application = create(:application)
 
-          expect(report.csv).to include([
+          expect(report.generate).to include([
             application.urn,
             application.applicant.full_name,
             application.applicant.date_of_birth.strftime("%d/%m/%Y"),
@@ -50,7 +50,7 @@ module Reports
         it "returns the data including rejection reasons in CSV format" do
           application = create(:application, application_progress: build(:application_progress, rejection_completed_at: Time.zone.now, status: :rejected, rejection_reason: :request_to_re_submit, rejection_details: "Some details"))
 
-          expect(report.csv).to include([
+          expect(report.generate).to include([
             application.urn,
             application.applicant.full_name,
             application.applicant.date_of_birth.strftime("%d/%m/%Y"),
@@ -85,7 +85,7 @@ module Reports
         ]
         expected_header += ["Rejection Reason", "Rejection Details"] if status == "rejected"
 
-        expect(report.csv).to include(expected_header.join(","))
+        expect(report.generate).to include(expected_header.join(","))
       end
     end
   end
diff --git a/spec/models/reports/standing_data_spec.rb b/spec/models/reports/standing_data_spec.rb
index c4cd9f6b..48cffccf 100644
--- a/spec/models/reports/standing_data_spec.rb
+++ b/spec/models/reports/standing_data_spec.rb
@@ -20,41 +20,41 @@ module Reports
       end
     end
 
-    describe "#csv" do
+    describe "#generate" do
       let(:progress) { build(:application_progress, school_checks_completed_at: Time.zone.now, banking_approval_completed_at: nil) }
 
       it "returns applicants who have completed initial checks but not home office checks" do
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).to include(app.urn)
+        expect(report.generate).to include(app.urn)
       end
 
       it "does not return rejected applicants" do
         progress.rejection_completed_at = Time.zone.now
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).not_to include(app.urn)
+        expect(report.generate).not_to include(app.urn)
       end
 
       it "does not return applicants who have not completed initial checks" do
         progress.school_checks_completed_at = nil
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).not_to include(app.urn)
+        expect(report.generate).not_to include(app.urn)
       end
 
       it "does not return applicants who have completed home office checks" do
         progress.banking_approval_completed_at = Time.zone.now
         app = create(:application, application_progress: progress)
 
-        expect(report.csv).not_to include(app.urn)
+        expect(report.generate).not_to include(app.urn)
       end
 
       # rubocop:disable RSpec/ExampleLength
       it "returns the data in CSV format" do
         application = create(:application, application_progress: progress)
 
-        expect(report.csv).to include([
+        expect(report.generate).to include([
           application.urn,
           application.applicant.given_name,
           application.applicant.middle_name,
@@ -80,12 +80,12 @@ module Reports
           Student_loan
         ].join(",")
 
-        expect(report.csv).to include(expected_header)
+        expect(report.generate).to include(expected_header)
       end
 
       context "includes applications from the csv before invoking `post_generation_hook`" do
         let(:app) { create(:application, application_progress: progress) }
-        let(:csv) { report.csv }
+        let(:csv) { report.generate }
 
         before { app }
 
diff --git a/spec/services/report_spec.rb b/spec/services/report_spec.rb
index 8f61a0b6..96d94aeb 100644
--- a/spec/services/report_spec.rb
+++ b/spec/services/report_spec.rb
@@ -56,7 +56,7 @@
       end
 
       it { expect(Reports::QaReport).to have_received(:new).with(status:) }
-      it { expect(report).to have_received(:csv) }
+      it { expect(report).to have_received(:generate) }
     end
 
     context "other report data" do
@@ -69,7 +69,7 @@
       end
 
       it { expect(Reports::HomeOffice).to have_received(:new) }
-      it { expect(report).to have_received(:csv) }
+      it { expect(report).to have_received(:generate) }
     end
     # rubocop:enable RSpec/VerifiedDoubles
   end