Total charge is inferred

app/models/case_log.rb

@@ -132,7 +132,7 @@ class CaseLog < ApplicationRecord
   enum la_known: POLAR, _suffix: true
   enum net_income_known: NET_INCOME_KNOWN, _suffix: true
 
-  AUTOGENERATED_FIELDS = %w[id status created_at updated_at discarded_at renttype lettype is_la_inferred totchild totelder totadult incfreq].freeze
+  AUTOGENERATED_FIELDS = %w[id status created_at updated_at discarded_at renttype lettype is_la_inferred totchild totelder totadult incfreq tcharge].freeze
   OPTIONAL_FIELDS = %w[postcode_known
                        la_known
                        first_time_property_let_as_social_housing].freeze
@@ -245,6 +245,7 @@ private
     self.totchild = get_totchild
     self.totelder = get_totelder
     self.totadult = get_totadult
+    self.tcharge = brent.to_i + scharge.to_i + pscharge.to_i + supcharg.to_i
   end
 
   def get_totelder

spec/models/case_log_spec.rb

@@ -1178,6 +1178,24 @@ RSpec.describe Form, type: :model do
       end
     end
 
+    context "rent and charges" do
+      let!(:case_log) do
+        CaseLog.create({
+          managing_organisation: organisation,
+          owning_organisation: organisation,
+          brent: 5,
+          scharge: 10,
+          pscharge: 3,
+          supcharg: 12
+        })
+      end
+
+      it "correctly sums rental charges" do
+        record_from_db = ActiveRecord::Base.connection.execute("select tcharge from case_logs where id=#{case_log.id}").to_a[0]
+        expect(record_from_db["tcharge"]).to eq(30)
+      end
+    end
+
     context "household members derived vars" do
       let!(:household_case_log) do
         CaseLog.create({