diff --git a/spec/models/form/sales/pages/service_charge_changed_spec.rb b/spec/models/form/sales/pages/service_charge_changed_spec.rb
new file mode 100644
index 000000000..4f313021a
--- /dev/null
+++ b/spec/models/form/sales/pages/service_charge_changed_spec.rb
@@ -0,0 +1,29 @@
+require "rails_helper"
+
+RSpec.describe Form::Sales::Pages::ServiceChargeChanged, type: :model do
+  subject(:page) { described_class.new(page_id, page_definition, subsection) }
+
+  let(:page_id) { nil }
+  let(:page_definition) { nil }
+  let(:subsection) { instance_double(Form::Subsection, form: instance_double(Form, start_date: Time.zone.local(2026, 4, 1))) }
+
+  it "has correct subsection" do
+    expect(page.subsection).to eq(subsection)
+  end
+
+  it "has correct questions" do
+    expect(page.questions.map(&:id)).to eq(%w[hasservicechargeschanged newservicecharges])
+  end
+
+  it "has the correct id" do
+    expect(page.id).to eq("service_charge_changed")
+  end
+
+  it "has the correct description" do
+    expect(page.description).to be_nil
+  end
+
+  it "has correct depends_on" do
+    expect(page.depends_on).to be_nil
+  end
+end
diff --git a/spec/models/form/sales/questions/has_service_charges_changed_spec.rb b/spec/models/form/sales/questions/has_service_charges_changed_spec.rb
new file mode 100644
index 000000000..f220ddd65
--- /dev/null
+++ b/spec/models/form/sales/questions/has_service_charges_changed_spec.rb
@@ -0,0 +1,54 @@
+require "rails_helper"
+
+RSpec.describe Form::Sales::Questions::HasServiceChargesChanged, type: :model do
+  subject(:question) { described_class.new(question_id, question_definition, page) }
+
+  let(:question_id) { nil }
+  let(:question_definition) { nil }
+  let(:subsection) { instance_double(Form::Subsection, form: instance_double(Form, start_date:)) }
+  let(:page) { instance_double(Form::Page, subsection:) }
+  let(:start_date) { Time.utc(2026, 5, 1) }
+
+  it "has correct page" do
+    expect(question.page).to eq(page)
+  end
+
+  it "has the correct id" do
+    expect(question.id).to eq("hasservicechargeschanged")
+  end
+
+  it "has the correct type" do
+    expect(question.type).to eq("radio")
+  end
+
+  it "is not marked as derived" do
+    expect(question.derived?(nil)).to be false
+  end
+
+  it "has the correct answer_options" do
+    expect(question.answer_options).to eq({
+      "1" => { "value" => "Yes" },
+      "2" => { "value" => "No" },
+    })
+  end
+
+  it "has correct conditional for" do
+    expect(question.conditional_for).to eq({
+      "newservicecharges" => [1],
+    })
+  end
+
+  it "has correct hidden_in_check_answers for" do
+    expect(question.hidden_in_check_answers).to eq({
+      "depends_on" => [
+        {
+          "hasservicechargeschanged" => 1,
+        },
+      ],
+    })
+  end
+
+  it "has the correct question number" do
+      expect(question.question_number).to eq(0)
+  end
+end
diff --git a/spec/models/form/sales/questions/new_service_charges_spec.rb b/spec/models/form/sales/questions/new_service_charges_spec.rb
new file mode 100644
index 000000000..3a5fea1b3
--- /dev/null
+++ b/spec/models/form/sales/questions/new_service_charges_spec.rb
@@ -0,0 +1,51 @@
+require "rails_helper"
+
+RSpec.describe Form::Sales::Questions::NewServiceCharges, type: :model do
+  subject(:question) { described_class.new(question_id, question_definition, page) }
+
+  let(:question_id) { nil }
+  let(:question_definition) { nil }
+  let(:subsection) { instance_double(Form::Subsection, form: instance_double(Form, start_date:)) }
+  let(:page) { instance_double(Form::Page, subsection:) }
+  let(:start_date) { Time.utc(2026, 5, 1) }
+
+  it "has correct page" do
+    expect(question.page).to eq(page)
+  end
+
+  it "has the correct id" do
+    expect(question.id).to eq("newservicecharges")
+  end
+
+  it "has the correct type" do
+    expect(question.type).to eq("numeric")
+  end
+
+  it "is not marked as derived" do
+    expect(question.derived?(nil)).to be false
+  end
+
+  it "has the correct width" do
+    expect(question.width).to be 5
+  end
+
+  it "has the correct min" do
+    expect(question.min).to be 0
+  end
+
+  it "has the correct max" do
+    expect(question.max).to be 9999.99
+  end
+
+  it "has the correct step" do
+    expect(question.step).to be 0.01
+  end
+
+  it "has the correct prefix" do
+    expect(question.prefix).to eq("£")
+  end
+
+  it "has the correct question number" do
+    expect(question.question_number).to eq(0)
+  end
+end
diff --git a/spec/models/validations/sales/financial_validations_spec.rb b/spec/models/validations/sales/financial_validations_spec.rb
index 80d10718b..390dd9dc7 100644
--- a/spec/models/validations/sales/financial_validations_spec.rb
+++ b/spec/models/validations/sales/financial_validations_spec.rb
@@ -478,4 +478,96 @@ RSpec.describe Validations::Sales::FinancialValidations do
       expect(record.errors).to be_empty
     end
   end
+
+  describe "#validate_newservicecharges" do
+    let(:record) { FactoryBot.build(:sales_log, ownershipsch: 1, staircase: 1) }
+
+    it "does not add errors when newservicecharges is nil" do
+      record.newservicecharges = nil
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when newservicecharges is valid" do
+      record.newservicecharges = 100.50
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "adds an error when newservicecharges is negative" do
+      record.newservicecharges = -50
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors["newservicecharges"]).to include(match I18n.t("validations.sales.financial.newservicecharges.negative"))
+    end
+
+    it "adds an error when newservicecharges is over the maximum" do
+      record.newservicecharges = 10_000
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors["newservicecharges"]).to include(match I18n.t("validations.sales.financial.newservicecharges.over_max"))
+    end
+
+    it "does not add errors when newservicecharges is exactly the maximum" do
+      record.newservicecharges = 9999.99
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when newservicecharges is zero" do
+      record.newservicecharges = 0
+      financial_validator.validate_newservicecharges(record)
+      expect(record.errors).to be_empty
+    end
+  end
+
+  describe "#validate_newservicecharges_different_from_mscharge" do
+    let(:record) { FactoryBot.build(:sales_log, ownershipsch: 1, staircase: 1) }
+
+    it "does not add errors when hasservicechargeschanged is nil" do
+      record.hasservicechargeschanged = nil
+      record.newservicecharges = 100
+      record.mscharge = 100
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when hasservicechargeschanged is 2 (No)" do
+      record.hasservicechargeschanged = 2
+      record.newservicecharges = 100
+      record.mscharge = 100
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when newservicecharges is nil" do
+      record.hasservicechargeschanged = 1
+      record.newservicecharges = nil
+      record.mscharge = 100
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when mscharge is nil" do
+      record.hasservicechargeschanged = 1
+      record.newservicecharges = 100
+      record.mscharge = nil
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "does not add errors when newservicecharges is different from mscharge" do
+      record.hasservicechargeschanged = 1
+      record.newservicecharges = 150
+      record.mscharge = 100
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "adds an error when hasservicechargeschanged is 1 (Yes) and newservicecharges equals mscharge" do
+      record.hasservicechargeschanged = 1
+      record.newservicecharges = 100
+      record.mscharge = 100
+      financial_validator.validate_newservicecharges_different_from_mscharge(record)
+      expect(record.errors["newservicecharges"]).to include(match I18n.t("validations.sales.financial.newservicecharges.same_as_previous"))
+    end
+  end
 end