diff --git a/app/services/bulk_upload/lettings/year2023/row_parser.rb b/app/services/bulk_upload/lettings/year2023/row_parser.rb
index 25b00302c..461bb7dac 100644
--- a/app/services/bulk_upload/lettings/year2023/row_parser.rb
+++ b/app/services/bulk_upload/lettings/year2023/row_parser.rb
@@ -362,13 +362,13 @@ class BulkUpload::Lettings::Year2023::RowParser
             on: :after_log
 
   validates :field_46, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 1 must be a number or the letter R" }, on: :after_log
-  validates :field_52, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 2 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_56, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 3 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_60, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 4 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_64, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 5 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_68, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 6 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_72, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 7 must be a number or the letter R" }, allow_blank: true, on: :after_log
-  validates :field_76, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 8 must be a number or the letter R" }, allow_blank: true, on: :after_log
+  validates :field_52, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 2 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(2).zero? }
+  validates :field_56, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 3 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(3).zero? }
+  validates :field_60, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 4 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(4).zero? }
+  validates :field_64, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 5 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(5).zero? }
+  validates :field_68, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 6 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(6).zero? }
+  validates :field_72, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 7 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(7).zero? }
+  validates :field_76, format: { with: /\A\d{1,3}\z|\AR\z/, message: "Age of person 8 must be a number or the letter R" }, on: :after_log, if: proc { details_known?(8).zero? }
 
   validate :validate_needs_type_present, on: :after_log
   validate :validate_data_types, on: :after_log
@@ -1068,28 +1068,28 @@ private
     attributes["declaration"] = field_45
 
     attributes["age1_known"] = age1_known?
-    attributes["age1"] = field_46 if attributes["age1_known"].zero? && field_46&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age1"] = field_46 if attributes["age1_known"]&.zero? && field_46&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age2_known"] = age2_known?
-    attributes["age2"] = field_52 if attributes["age2_known"].zero? && field_52&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age2"] = field_52 if attributes["age2_known"]&.zero? && field_52&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age3_known"] = age3_known?
-    attributes["age3"] = field_56 if attributes["age3_known"].zero? && field_56&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age3"] = field_56 if attributes["age3_known"]&.zero? && field_56&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age4_known"] = age4_known?
-    attributes["age4"] = field_60 if attributes["age4_known"].zero? && field_60&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age4"] = field_60 if attributes["age4_known"]&.zero? && field_60&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age5_known"] = age5_known?
-    attributes["age5"] = field_64 if attributes["age5_known"].zero? && field_64&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age5"] = field_64 if attributes["age5_known"]&.zero? && field_64&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age6_known"] = age6_known?
-    attributes["age6"] = field_68 if attributes["age6_known"].zero? && field_68&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age6"] = field_68 if attributes["age6_known"]&.zero? && field_68&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age7_known"] = age7_known?
-    attributes["age7"] = field_72 if attributes["age7_known"].zero? && field_72&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age7"] = field_72 if attributes["age7_known"]&.zero? && field_72&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["age8_known"] = age8_known?
-    attributes["age8"] = field_76 if attributes["age8_known"].zero? && field_76&.match(/\A\d{1,3}\z|\AR\z/)
+    attributes["age8"] = field_76 if attributes["age8_known"]&.zero? && field_76&.match(/\A\d{1,3}\z|\AR\z/)
 
     attributes["sex1"] = field_47
     attributes["sex2"] = field_53
@@ -1372,7 +1372,6 @@ private
 
   def age1_known?
     return 1 if field_46 == "R"
-    return 1 if field_46.blank?
 
     0
   end
@@ -1389,9 +1388,6 @@ private
     define_method("age#{hash[:person]}_known?") do
       return 1 if public_send(hash[:field]) == "R"
       return 0 if send("person_#{hash[:person]}_present?")
-      return 1 if public_send(hash[:field]).blank?
-
-      0
     end
   end
 
diff --git a/spec/services/bulk_upload/lettings/year2023/row_parser_spec.rb b/spec/services/bulk_upload/lettings/year2023/row_parser_spec.rb
index af713d29b..662962250 100644
--- a/spec/services/bulk_upload/lettings/year2023/row_parser_spec.rb
+++ b/spec/services/bulk_upload/lettings/year2023/row_parser_spec.rb
@@ -1711,25 +1711,44 @@ RSpec.describe BulkUpload::Lettings::Year2023::RowParser do
     end
 
     [
-      %w[age1_known age1 field_46],
-      %w[age2_known age2 field_52],
-      %w[age3_known age3 field_56],
-      %w[age4_known age4 field_60],
-      %w[age5_known age5 field_64],
-      %w[age6_known age6 field_68],
-      %w[age7_known age7 field_72],
-      %w[age8_known age8 field_76],
-    ].each do |known, age, field|
+      %w[age1_known details_known_1 age1 field_46 field_51 field_53],
+      %w[age2_known details_known_2 age2 field_52 field_51 field_53],
+      %w[age3_known details_known_3 age3 field_56 field_55 field_57],
+      %w[age4_known details_known_4 age4 field_60 field_59 field_61],
+      %w[age5_known details_known_5 age5 field_64 field_63 field_65],
+      %w[age6_known details_known_6 age6 field_68 field_67 field_69],
+      %w[age7_known details_known_7 age7 field_72 field_71 field_73],
+      %w[age8_known details_known_8 age8 field_76 field_75 field_77],
+    ].each do |known, details_known, age, field, relationship, gender|
       describe "##{known} and ##{age}" do
         context "when #{field} is blank" do
-          let(:attributes) { { bulk_upload:, field.to_s => nil, field_4: 1 } }
+          context "and person details are not given" do
+            let(:attributes) { { bulk_upload:, field.to_sym => nil, field_4: 1, relationship.to_sym => nil, gender.to_sym => nil } }
 
-          it "sets ##{known} 1" do
-            expect(parser.log.public_send(known)).to be(1)
+            it "does not set ##{known}" do
+              unless known == "age1_known"
+                expect(parser.log.public_send(known)).to be_nil
+              end
+            end
+
+            it "sets ##{details_known} to no" do
+              unless details_known == "details_known_1"
+                expect(parser.log.public_send(details_known)).to eq(1)
+              end
+            end
+
+            it "sets ##{age} to nil" do
+              expect(parser.log.public_send(age)).to be_nil
+            end
           end
 
-          it "sets ##{age} to nil" do
-            expect(parser.log.public_send(age)).to be_nil
+          context "and person details are given" do
+            let(:attributes) { { bulk_upload:, field.to_sym => nil, field_4: 1, relationship.to_sym => "C", gender.to_sym => "X" } }
+
+            it "does not set ##{age}" do
+              parser.valid?
+              expect(parser.errors[field.to_sym]).to include(/must be a number or the letter R/)
+            end
           end
         end