add a validation against the case where monthly leashold charges are zero, test this, remove unnecessary validation on cash discount as this is covered by validate_numeric_min_max

app/models/form/sales/questions/leasehold_charges.rb

@@ -5,7 +5,7 @@ class Form::Sales::Questions::LeaseholdCharges < ::Form::Question
     @check_answer_label = "Monthly leasehold charges"
     @header = "Enter the total monthly charge"
     @type = "numeric"
-    @min = 0
+    @min = 1
     @width = 5
     @prefix = "£"
     @ownershipsch = ownershipsch

app/models/validations/sales/financial_validations.rb

@@ -40,12 +40,8 @@ module Validations::Sales::FinancialValidations
     record.errors.add :mortgage, :cannot_be_0, message: I18n.t("validations.financial.mortgage") if record.mortgage_used? && record.mortgage&.zero?
   end
 
-  def validate_cash_discount(record)
-    return unless record.cashdis
-
-    unless record.cashdis.between?(0, 999_999)
-      record.errors.add :cashdis, I18n.t("validations.financial.cash_discount_invalid")
-    end
+  def validate_monthly_leasehold_charges(record)
+    record.errors.add :mscharge, I18n.t("validations.financial.monthly_leasehold_charges.not_zero") if record.mscharge == 0
   end
 
   def validate_percentage_bought_not_greater_than_percentage_owned(record)

config/locales/en.yml

@@ -320,6 +320,8 @@ en:
         percentage_bought_must_be_greater_than_percentage_owned: "Total percentage buyer now owns must be more than percentage bought in this transaction"
         older_person_percentage_owned_maximum_75: "Percentage cannot be above 75% under Older Person's Shared Ownership"
         percentage_bought_must_be_at_least_threshold: "The minimum increase in equity while staircasing is %{threshold}%"
+      monthly_leasehold_charges:
+        not_zero: "Monthly leasehold charges cannot be £0 if the property has monthly charges"
       equity:
         under_min: "The minimum initial equity stake for this type of shared ownership sale is %{min_equity}%"
         over_max: "The maximum initial equity stake is %{max_equity}%"

spec/models/validations/sales/financial_validations_spec.rb

@@ -131,28 +131,6 @@ RSpec.describe Validations::Sales::FinancialValidations do
     end
   end
 
-  describe "#validate_cash_discount" do
-    let(:record) { FactoryBot.create(:sales_log) }
-
-    it "adds an error if the cash discount is below zero" do
-      record.cashdis = -1
-      financial_validator.validate_cash_discount(record)
-      expect(record.errors["cashdis"]).to include(match I18n.t("validations.financial.cash_discount_invalid"))
-    end
-
-    it "adds an error if the cash discount is one million or more" do
-      record.cashdis = 1_000_000
-      financial_validator.validate_cash_discount(record)
-      expect(record.errors["cashdis"]).to include(match I18n.t("validations.financial.cash_discount_invalid"))
-    end
-
-    it "does not add an error if the cash discount is in the expected range" do
-      record.cashdis = 10_000
-      financial_validator.validate_cash_discount(record)
-      expect(record.errors).to be_empty
-    end
-  end
-
   describe "#validate_percentage_bought_not_greater_than_percentage_owned" do
     let(:record) { FactoryBot.create(:sales_log) }
 
@@ -178,6 +156,22 @@ RSpec.describe Validations::Sales::FinancialValidations do
     end
   end
 
+  describe "#validate_monthly_leasehold_charges", focus: true do
+    let(:record) { FactoryBot.create(:sales_log) }
+
+    it "does not add an error if monthly leasehold charges are positive" do
+      record.mscharge = 2345
+      financial_validator.validate_monthly_leasehold_charges(record)
+      expect(record.errors).to be_empty
+    end
+
+    it "adds an error if monthly leasehold charges are zero" do
+      record.mscharge = 0
+      financial_validator.validate_monthly_leasehold_charges(record)
+      expect(record.errors[:mscharge]).to include I18n.t("validations.financial.monthly_leasehold_charges.not_zero")
+    end
+  end
+
   describe "#validate_percentage_bought_at_least_threshold" do
     let(:record) { FactoryBot.create(:sales_log) }