diff --git a/app/models/lettings_log.rb b/app/models/lettings_log.rb
index 0041f3200..69769b782 100644
--- a/app/models/lettings_log.rb
+++ b/app/models/lettings_log.rb
@@ -8,6 +8,7 @@ class LettingsLogValidator < ActiveModel::Validator
   include Validations::TenancyValidations
   include Validations::DateValidations
   include Validations::LocalAuthorityValidations
+
   def validate(record)
     validation_methods = public_methods.select { |method| method.starts_with?("validate_") }
     validation_methods.each { |meth| public_send(meth, record) }
diff --git a/app/services/bulk_upload/lettings/row_parser.rb b/app/services/bulk_upload/lettings/row_parser.rb
index e2831b799..1eae1d639 100644
--- a/app/services/bulk_upload/lettings/row_parser.rb
+++ b/app/services/bulk_upload/lettings/row_parser.rb
@@ -137,10 +137,27 @@ class BulkUpload::Lettings::RowParser
   attribute :field_133, :integer
   attribute :field_134, :integer
 
+  validates :field_1, presence: true, inclusion: { in: (1..12).to_a }
+
+  def attribute_set
+    @attribute_set ||= instance_variable_get(:@attributes)
+  end
+
+  def validate_data_types
+    unless attribute_set["field_1"].value_before_type_cast&.match?(/\A\d+\z/)
+      errors.add(:field_1, :invalid)
+    end
+  end
+
   def valid?
+    errors.clear
+
+    super
+
+    validate_data_types
+
     log.valid?
 
-    errors.clear
 
     log.errors.each do |error|
       field = field_for_attribute(error.attribute)
@@ -160,6 +177,7 @@ private
 
   def field_mapping
     {
+      field_1: :lettype,
       field_134: :renewal,
     }
   end
diff --git a/spec/services/bulk_upload/lettings/row_parser_spec.rb b/spec/services/bulk_upload/lettings/row_parser_spec.rb
index 50a9e8772..7a5490c2a 100644
--- a/spec/services/bulk_upload/lettings/row_parser_spec.rb
+++ b/spec/services/bulk_upload/lettings/row_parser_spec.rb
@@ -20,7 +20,41 @@ RSpec.describe BulkUpload::Lettings::RowParser do
       end
     end
 
-    describe "field_134" do
+    describe "#field_1" do
+      context "when null" do
+        let(:attributes) { { field_1: nil } }
+
+        it "returns an error" do
+          expect(parser.errors[:field_1]).to be_present
+        end
+      end
+
+      context "when incorrect data type" do
+        let(:attributes) { { field_1: "foo" } }
+
+        it "returns an error" do
+          expect(parser.errors[:field_1]).to be_present
+        end
+      end
+
+      context "when unpermitted value" do
+        let(:attributes) { { field_1: "101" } }
+
+        it "returns an error" do
+          expect(parser.errors[:field_1]).to be_present
+        end
+      end
+
+      context "when valid" do
+        let(:attributes) { { field_1: "1" } }
+
+        it "does not return any errors" do
+          expect(parser.errors[:field_1]).to be_blank
+        end
+      end
+    end
+
+    describe "#field_134" do
       context "when an unpermitted value" do
         let(:attributes) { { field_134: 3 } }