diff --git a/app/models/lettings_log.rb b/app/models/lettings_log.rb
index 1b9b74bb8..8ebf8092f 100644
--- a/app/models/lettings_log.rb
+++ b/app/models/lettings_log.rb
@@ -213,28 +213,14 @@ class LettingsLog < Log
     format_as_currency((field_value * 52) / num_of_weeks)
   end
 
-  def all_relevant_ecstat_provided
-    return false unless ecstat1
-
-    if hhmemb && hhmemb > 1
-      (2..hhmemb).each do |person_index|
-        next if details_not_known_for_person?(person_index)
-
-        return false unless self["ecstat#{person_index}"]
-      end
-    end
-
-    true
-  end
-
   def applicable_income_range
-    return unless all_relevant_ecstat_provided
+    return unless ecstat1 && hhmemb
 
     range = ALLOWED_INCOME_RANGES[ecstat1].clone
 
-    if hhmemb && hhmemb > 1
+    if hhmemb > 1
       (2..hhmemb).each do |person_index|
-        ecstat = details_not_known_for_person?(person_index) ? 10 : self["ecstat#{person_index}"]
+        ecstat = self["ecstat#{person_index}"] || 10
 
         person_range = ALLOWED_INCOME_RANGES[ecstat]
         range.soft_min += person_range.soft_min
diff --git a/app/models/validations/financial_validations.rb b/app/models/validations/financial_validations.rb
index defc4eedf..4da2201e7 100644
--- a/app/models/validations/financial_validations.rb
+++ b/app/models/validations/financial_validations.rb
@@ -24,15 +24,20 @@ module Validations::FinancialValidations
   end
 
   def validate_net_income(record)
-    if record.all_relevant_ecstat_provided && record.weekly_net_income
+    if record.ecstat1 && record.hhmemb && record.weekly_net_income
+      frequency = record.form.get_question("incfreq", record).label_from_value(record.incfreq).downcase
       if record.weekly_net_income > record.applicable_income_range.hard_max
         hard_max = format_as_currency(record.applicable_income_range.hard_max)
-        frequency = record.form.get_question("incfreq", record).label_from_value(record.incfreq).downcase
         record.errors.add(
           :earnings,
           :over_hard_max,
           message: I18n.t("validations.financial.earnings.over_hard_max", hard_max:),
         )
+        record.errors.add(
+          :hhmemb,
+          :over_hard_max,
+          message: I18n.t("validations.financial.hhmemb.earnings.over_hard_max", earnings: format_as_currency(record.earnings), frequency:),
+        )
         ecstat_fields = %i[ecstat1 ecstat2 ecstat3 ecstat4 ecstat5 ecstat6 ecstat7 ecstat8]
         ecstat_fields.each do |field|
           record.errors.add(
@@ -47,7 +52,7 @@ module Validations::FinancialValidations
           record.errors.add(
             "age#{n}",
             :over_hard_max,
-            message: I18n.t("validations.financial.ecstat.inferred_child.over_hard_max", earnings: format_as_currency(record.earnings), frequency:),
+            message: I18n.t("validations.financial.age.earnings_over_hard_max", earnings: format_as_currency(record.earnings), frequency:),
           )
         end
       end
@@ -59,6 +64,20 @@ module Validations::FinancialValidations
           :under_hard_min,
           message: I18n.t("validations.financial.earnings.under_hard_min", hard_min:),
         )
+        record.errors.add(
+          :hhmemb,
+          :under_hard_min,
+          message: I18n.t("validations.financial.hhmemb.earnings.under_hard_min", earnings: format_as_currency(record.earnings), frequency:),
+        )
+        ecstat_fields = %i[ecstat1 ecstat2 ecstat3 ecstat4 ecstat5 ecstat6 ecstat7 ecstat8]
+        ecstat_fields.each do |field|
+          record.errors.add(
+            field,
+            :under_hard_min,
+            message: I18n.t("validations.financial.ecstat.under_hard_min", earnings: format_as_currency(record.earnings), frequency:),
+          )
+        end
+        # N.B. It is not possible for a change to an age field to increase the hard min
       end
     end
 
diff --git a/app/models/validations/soft_validations.rb b/app/models/validations/soft_validations.rb
index 7c4f5c65d..92685afe0 100644
--- a/app/models/validations/soft_validations.rb
+++ b/app/models/validations/soft_validations.rb
@@ -14,13 +14,13 @@ module Validations::SoftValidations
   }.freeze
 
   def net_income_in_soft_max_range?
-    return unless weekly_net_income && all_relevant_ecstat_provided
+    return unless weekly_net_income && ecstat1 && hhmemb
 
     weekly_net_income.between?(applicable_income_range.soft_max, applicable_income_range.hard_max)
   end
 
   def net_income_in_soft_min_range?
-    return unless weekly_net_income && all_relevant_ecstat_provided
+    return unless weekly_net_income && ecstat1 && hhmemb
 
     weekly_net_income.between?(applicable_income_range.hard_min, applicable_income_range.soft_min)
   end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 5b35aaae8..7e8720cf0 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -377,8 +377,13 @@ en:
         out_of_range: "Enter a value for the %{charge_name} between £0 and %{maximum_per_period} paid %{frequency}. %{maximum_per_period} is the max limit for rent and charges paid %{frequency} for %{letting_type} lettings owned by a %{provider_type}."
       ecstat:
         over_hard_max: "The household's income of %{earnings} %{frequency} is too high given the household’s working situation"
-        inferred_child:
-          over_hard_max: "The household's income of %{earnings} %{frequency} is too high given the household’s characteristics and working situation"
+        under_hard_min: "The household's income of %{earnings} %{frequency} is too low given the household’s working situation"
+      age:
+        earnings_over_hard_max: "The household's income of %{earnings} %{frequency} is too high for the number of adults. Change either the household income or the age of the tenants."
+      hhmemb:
+        earnings:
+          over_hard_max: "The household's income of %{earnings} %{frequency} is too high for this number of tenants. Change either the household income or number of tenants."
+          under_hard_min: "The household's income of %{earnings} %{frequency} is too low for this number of tenants. Change either the household income or number of tenants."
       brent:
         below_hard_min: "Rent is below the absolute minimum expected for a property of this type. Please check the rent, rent period, local authority and (if general needs) number of bedrooms"
         above_hard_max: "Rent is higher than the absolute maximum expected for a property of this type. Please check the rent, rent period, local authority and (if general needs) number of bedrooms"
diff --git a/spec/features/form/validations_spec.rb b/spec/features/form/validations_spec.rb
index 561f31c8d..497897f8d 100644
--- a/spec/features/form/validations_spec.rb
+++ b/spec/features/form/validations_spec.rb
@@ -131,6 +131,7 @@ RSpec.describe "validations" do
         FactoryBot.create(
           :lettings_log,
           :in_progress,
+          hhmemb: 1,
           ecstat1: 1,
           created_by: user,
         )
diff --git a/spec/models/lettings_log_spec.rb b/spec/models/lettings_log_spec.rb
index 6a5ba1477..1b641f452 100644
--- a/spec/models/lettings_log_spec.rb
+++ b/spec/models/lettings_log_spec.rb
@@ -3412,30 +3412,34 @@ RSpec.describe LettingsLog do
     end
   end
 
-  describe "#all_relevant_ecstat_provided" do
-    context "when details for a non-lead tenant are not known" do
-      let(:lettings_log) { build(:lettings_log, hhmemb: 2, ecstat1: 1, details_known_2: 1) }
-
-      it "returns true" do
-        expect(lettings_log.all_relevant_ecstat_provided).to be(true)
+  describe "#applicable_income_range" do
+    context "when ecstat for a non-lead tenant is not set" do
+      let(:lettings_log) { build(:lettings_log, hhmemb: 2, ecstat1: 1) }
+
+      it "uses the prefers-not-to-say values for that tenant to calculate the range" do
+        range = lettings_log.applicable_income_range
+        expected_range = OpenStruct.new(
+          soft_min: 143 + 47,
+          soft_max: 730 + 730,
+          hard_min: 90 + 10,
+          hard_max: 1230 + 2000,
+        )
+        expect(range).to eq(expected_range)
       end
     end
 
-    context "when details for a non-lead tenant are known" do
-      context "and that person's ecstat is provided" do
-        let(:lettings_log) { build(:lettings_log, hhmemb: 2, ecstat1: 1, details_known_2: 0, ecstat2: 2) }
+    context "when ecstat for a non-lead tenant is set" do
+      let(:lettings_log) { build(:lettings_log, hhmemb: 2, ecstat1: 1, ecstat2: 2) }
 
-        it "returns true" do
-          expect(lettings_log.all_relevant_ecstat_provided).to be(true)
-        end
-      end
-
-      context "and that person's ecstat is not provided" do
-        let(:lettings_log) { build(:lettings_log, hhmemb: 2, ecstat1: 1, details_known_2: 0) }
-
-        it "returns true" do
-          expect(lettings_log.all_relevant_ecstat_provided).to be(false)
-        end
+      it "uses the relevant income range values for that tenant to calculate the range" do
+        range = lettings_log.applicable_income_range
+        expected_range = OpenStruct.new(
+          soft_min: 143 + 67,
+          soft_max: 730 + 620,
+          hard_min: 90 + 50,
+          hard_max: 1230 + 950,
+        )
+        expect(range).to eq(expected_range)
       end
     end
   end
diff --git a/spec/models/validations/financial_validations_spec.rb b/spec/models/validations/financial_validations_spec.rb
index 49a1c8de7..3b3d70546 100644
--- a/spec/models/validations/financial_validations_spec.rb
+++ b/spec/models/validations/financial_validations_spec.rb
@@ -190,6 +190,7 @@ RSpec.describe Validations::FinancialValidations do
     it "validates that the net income is within the expected range for the household’s employment status" do
       record.earnings = 200
       record.incfreq = 1
+      record.hhmemb = 1
       record.ecstat1 = 1
       financial_validator.validate_net_income(record)
       expect(record.errors["earnings"]).to be_empty
@@ -199,12 +200,15 @@ RSpec.describe Validations::FinancialValidations do
       it "adds an error" do
         record.earnings = 5000
         record.incfreq = 1
+        record.hhmemb = 1
         record.ecstat1 = 1
         financial_validator.validate_net_income(record)
         expect(record.errors["earnings"])
           .to eq(["The household's income cannot be greater than £1,230.00 per week given the household’s working situation"])
         expect(record.errors["ecstat1"])
           .to eq(["The household's income of £5,000.00 weekly is too high given the household’s working situation"])
+        expect(record.errors["hhmemb"])
+          .to eq(["The household's income of £5,000.00 weekly is too high for this number of tenants. Change either the household income or number of tenants."])
       end
     end
 
@@ -212,10 +216,15 @@ RSpec.describe Validations::FinancialValidations do
       it "adds an error" do
         record.earnings = 50
         record.incfreq = 1
+        record.hhmemb = 1
         record.ecstat1 = 1
         financial_validator.validate_net_income(record)
         expect(record.errors["earnings"])
           .to eq(["The household's income cannot be less than £90.00 per week given the household’s working situation"])
+        expect(record.errors["ecstat1"])
+          .to eq(["The household's income of £50.00 weekly is too low given the household’s working situation"])
+        expect(record.errors["hhmemb"])
+          .to eq(["The household's income of £50.00 weekly is too low for this number of tenants. Change either the household income or number of tenants."])
       end
     end
 
@@ -260,7 +269,22 @@ RSpec.describe Validations::FinancialValidations do
         expect(record.errors["age1"]).to be_empty
         expect(record.errors["age2"]).to be_empty
         expect(record.errors["age3"])
-          .to eq(["The household's income of £5,000.00 weekly is too high given the household’s characteristics and working situation"])
+          .to eq(["The household's income of £5,000.00 weekly is too high for the number of adults. Change either the household income or the age of the tenants."])
+      end
+
+      it "adds errors to relevant fields for each tenant when income is too low" do
+        record.earnings = 50
+        record.incfreq = 1
+        record.hhmemb = 3
+        record.ecstat1 = 1
+        record.ecstat2 = 2
+        record.age3 = 12
+        record.ecstat3 = 9
+        financial_validator.validate_net_income(record)
+        (1..record.hhmemb).each do |n|
+          expect(record.errors["ecstat#{n}"])
+            .to eq(["The household's income of £50.00 weekly is too low given the household’s working situation"])
+        end
       end
     end
   end