diff --git a/app/contracts/work_packages/base_contract.rb b/app/contracts/work_packages/base_contract.rb
index 65342ddf3166..a43c9ef95279 100644
--- a/app/contracts/work_packages/base_contract.rb
+++ b/app/contracts/work_packages/base_contract.rb
@@ -57,12 +57,15 @@ class BaseContract < ::ModelContract
     attribute :derived_done_ratio,
               writable: false
 
-    attribute :estimated_hours
+    attribute :estimated_hours do
+      validate_work_is_set_when_remaining_work_is_set
+    end
     attribute :derived_estimated_hours,
               writable: false
 
     attribute :remaining_hours do
-      validate_remaining_hours_doesnt_exceed_estimated_hours
+      validate_remaining_work_is_lower_than_work
+      validate_remaining_work_is_set_when_work_is_set
     end
     attribute :derived_remaining_hours,
               writable: false
@@ -320,8 +323,8 @@ def validate_version_is_assignable
       end
     end
 
-    def validate_remaining_hours_doesnt_exceed_estimated_hours
-      if both_remaining_and_estimated_hours_present? && remaining_work_exceeds_work?
+    def validate_remaining_work_is_lower_than_work
+      if work_set? && remaining_work_set? && remaining_work_exceeds_work?
         if model.changed.include?("estimated_hours")
           errors.add(:estimated_hours, :cant_be_inferior_to_remaining_work)
         end
@@ -332,8 +335,24 @@ def validate_remaining_hours_doesnt_exceed_estimated_hours
       end
     end
 
-    def both_remaining_and_estimated_hours_present?
-      model.remaining_hours.present? && model.estimated_hours.present?
+    def validate_remaining_work_is_set_when_work_is_set
+      if work_set? && !remaining_work_set?
+        errors.add(:remaining_hours, :must_be_set_when_work_is_set)
+      end
+    end
+
+    def validate_work_is_set_when_remaining_work_is_set
+      if remaining_work_set? && !work_set?
+        errors.add(:estimated_hours, :must_be_set_when_remaining_work_is_set)
+      end
+    end
+
+    def work_set?
+      model.estimated_hours.present?
+    end
+
+    def remaining_work_set?
+      model.remaining_hours.present?
     end
 
     def remaining_work_exceeds_work?
diff --git a/app/services/work_packages/set_attributes_service.rb b/app/services/work_packages/set_attributes_service.rb
index 68d8d8d4bfd6..acff442134c2 100644
--- a/app/services/work_packages/set_attributes_service.rb
+++ b/app/services/work_packages/set_attributes_service.rb
@@ -360,18 +360,16 @@ def invalid_progress_values?
     work && remaining_work && remaining_work > work
   end
 
-  # rubocop:disable Metrics/AbcSize
   def update_estimated_hours
     return unless WorkPackage.use_field_for_done_ratio?
     return if work_package.estimated_hours_changed?
     return if work_package.estimated_hours.present?
     return unless work_package.remaining_hours_changed?
 
-    if work_package.remaining_hours.present? && work_package.done_ratio.present?
+    if work_package.remaining_hours.present?
       work_package.estimated_hours = estimated_hours_from_done_ratio_and_remaining_hours
     end
   end
-  # rubocop:enable Metrics/AbcSize
 
   # When in "Status-based" mode for % Complete, remaining hours are based
   # on the computation of it derived from the status's default done ratio
@@ -397,7 +395,7 @@ def update_remaining_hours
   # rubocop:enable Metrics/AbcSize,Metrics/PerceivedComplexity
 
   def estimated_hours_from_done_ratio_and_remaining_hours
-    remaining_ratio = 1.0 - (work_package.done_ratio / 100.0)
+    remaining_ratio = 1.0 - ((work_package.done_ratio || 0) / 100.0)
     work_package.remaining_hours / remaining_ratio
   end
 
@@ -405,7 +403,7 @@ def remaining_hours_from_done_ratio_and_estimated_hours
     return nil if work_package.done_ratio.nil? || work_package.estimated_hours.nil?
 
     completed_work = work_package.estimated_hours * work_package.done_ratio / 100.0
-    work_package.estimated_hours - completed_work
+    (work_package.estimated_hours - completed_work).round(2)
   end
 
   def set_version_to_nil
diff --git a/config/locales/en.yml b/config/locales/en.yml
index f14f2ab790d9..2327f8e7ddb5 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -1024,10 +1024,12 @@ Project attributes and sections are defined in the <a href=%{admin_settings_url}
               only_same_project_categories_allowed: "The category of a work package must be within the same project as the work package."
               does_not_exist: "The specified category does not exist."
             estimated_hours:
+              cant_be_inferior_to_remaining_work: "can't be inferior to 'Remaining work'."
+              must_be_set_when_remaining_work_is_set: "must be set when 'Remaining work' is set."
               only_values_greater_or_equal_zeroes_allowed: "must be >= 0."
-              cant_be_inferior_to_remaining_work: "can't be inferior to 'Remaining work'"
             remaining_hours:
-              cant_exceed_work: "can't exceed 'Work'"
+              cant_exceed_work: "can't exceed 'Work'."
+              must_be_set_when_work_is_set: "must be set when 'Work' is set."
           readonly_status: "The work package is in a readonly status so its attributes cannot be changed."
         type:
           attributes:
diff --git a/db/migrate/20240328154805_change_status_default_done_ratio_to_zero.rb b/db/migrate/20240328154805_change_status_default_done_ratio_to_zero.rb
new file mode 100644
index 000000000000..b430e0966946
--- /dev/null
+++ b/db/migrate/20240328154805_change_status_default_done_ratio_to_zero.rb
@@ -0,0 +1,11 @@
+class ChangeStatusDefaultDoneRatioToZero < ActiveRecord::Migration[7.1]
+  def change
+    change_column_default :statuses, :default_done_ratio, from: nil, to: 0
+    reversible do |dir|
+      dir.up do
+        execute "UPDATE statuses SET default_done_ratio = 0 WHERE default_done_ratio IS NULL"
+      end
+    end
+    change_column_null :statuses, :default_done_ratio, false
+  end
+end
diff --git a/modules/backlogs/spec/api/work_package_resource_spec.rb b/modules/backlogs/spec/api/work_package_resource_spec.rb
index 8954e078c884..d2cc6590f82e 100644
--- a/modules/backlogs/spec/api/work_package_resource_spec.rb
+++ b/modules/backlogs/spec/api/work_package_resource_spec.rb
@@ -39,6 +39,7 @@
     create(:work_package,
            project:,
            story_points: 8,
+           estimated_hours: 5,
            remaining_hours: 5)
   end
   let(:wp_path) { "/api/v3/work_packages/#{work_package.id}" }
diff --git a/modules/backlogs/spec/services/stories/create_service_spec.rb b/modules/backlogs/spec/services/stories/create_service_spec.rb
index 4f0caf212801..c1ca11146b69 100644
--- a/modules/backlogs/spec/services/stories/create_service_spec.rb
+++ b/modules/backlogs/spec/services/stories/create_service_spec.rb
@@ -30,22 +30,12 @@
 
 RSpec.describe Stories::CreateService, type: :model do
   let(:priority) { create(:priority) }
-  let(:project) do
-    project = create(:project, types: [type_feature])
-
-    create(:member,
-           principal: user,
-           project:,
-           roles: [role])
-    project
-  end
-  let(:role) { create(:project_role, permissions:) }
-  let(:permissions) { %i(add_work_packages manage_subtasks assign_versions) }
+  let(:project) { create(:project, types: [type_feature]) }
   let(:status) { create(:status) }
   let(:type_feature) { create(:type_feature) }
 
   let(:user) do
-    create(:user)
+    create(:user, member_with_permissions: { project => %i(add_work_packages manage_subtasks assign_versions) })
   end
 
   let(:instance) do
@@ -67,8 +57,6 @@
   let(:version) { create(:version, project:) }
 
   let(:story) do
-    project.enabled_module_names += ["backlogs"]
-
     create(:story,
            version:,
            project:,
@@ -83,24 +71,30 @@
 
   subject { instance.call(attributes:) }
 
-  describe "remaining_hours" do
+  describe "creating a feature in a story" do
     before do
       subject
     end
 
-    context "with the story having remaining_hours" do
+    context "with the feature being created with some remaining work (remaining hours)" do
       let(:remaining_hours) { 15.0 }
 
-      it "does update the parents remaining hours" do
-        expect(story.reload.derived_remaining_hours).to eq(15)
+      it "updates the story total work, total remaining work, and total % complete" do
+        expect(subject).to be_success
+        expect(story.reload).to have_attributes(derived_estimated_hours: 15,
+                                                derived_remaining_hours: 15,
+                                                derived_done_ratio: 0)
       end
     end
 
-    context "with the subtask not having remaining_hours" do
+    context "with the feature being created without any remaining work (remaining hours)" do
       let(:remaining_hours) { nil }
 
-      it "does not note remaining hours to be changed" do
-        expect(story.reload.remaining_hours).to be_nil
+      it "does not change the story total work, total remaining work, and total % complete" do
+        expect(subject).to be_success
+        expect(story.reload).to have_attributes(derived_estimated_hours: nil,
+                                                derived_remaining_hours: nil,
+                                                derived_done_ratio: nil)
       end
     end
   end
diff --git a/spec/contracts/work_packages/base_contract_spec.rb b/spec/contracts/work_packages/base_contract_spec.rb
index a57540730ba2..a24c86069d2d 100644
--- a/spec/contracts/work_packages/base_contract_spec.rb
+++ b/spec/contracts/work_packages/base_contract_spec.rb
@@ -30,6 +30,8 @@
 require "contracts/shared/model_contract_shared_context"
 
 RSpec.describe WorkPackages::BaseContract do
+  include_context "ModelContract shared context"
+
   let(:work_package) do
     build_stubbed(:work_package,
                   type:,
@@ -66,8 +68,6 @@
 
   subject(:contract) { described_class.new(work_package, current_user) }
 
-  include_context "ModelContract shared context"
-
   shared_examples_for "invalid if changed" do |attribute|
     before do
       allow(work_package).to receive(:changed).and_return(changed_values.map(&:to_s))
@@ -290,76 +290,58 @@
     end
   end
 
-  describe "estimated hours" do
+  describe "work (estimated hours)" do
     let(:estimated_hours) { 1 }
+    let(:remaining_hours) { 0 }
 
     before do
       work_package.estimated_hours = estimated_hours
-      work_package.remaining_hours = nil
+      work_package.remaining_hours = remaining_hours
+      work_package.clear_remaining_hours_change
     end
 
     context "when > 0" do
       let(:estimated_hours) { 1 }
 
-      it "is valid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to be_empty
-      end
+      include_examples "contract is valid"
     end
 
     context "when 0" do
       let(:estimated_hours) { 0 }
 
-      it "is valid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to be_empty
-      end
+      include_examples "contract is valid"
     end
 
-    context "when nil" do
+    context "when nil while remaining work is nil" do
       let(:estimated_hours) { nil }
+      let(:remaining_hours) { nil }
 
-      it "is valid" do
-        contract.validate
+      include_examples "contract is valid"
+    end
 
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to be_empty
-      end
+    context "when nil while remaining work is set" do
+      let(:estimated_hours) { nil }
+      let(:remaining_hours) { 2.0 }
+
+      include_examples "contract is invalid", estimated_hours: :must_be_set_when_remaining_work_is_set
     end
 
     context "when < 0" do
       let(:estimated_hours) { -1 }
+      let(:remaining_hours) { -2 }
 
-      it "is invalid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to contain_exactly(:only_values_greater_or_equal_zeroes_allowed)
-      end
+      include_examples "contract is invalid", estimated_hours: :only_values_greater_or_equal_zeroes_allowed
     end
 
-    context "when inferior to remaining_hours" do
+    context "when inferior to remaining work" do
       let(:estimated_hours) { 5.0 }
+      let(:remaining_hours) { 7.0 }
 
-      before do
-        work_package.remaining_hours = 6.0
-        allow(work_package).to receive(:changed).and_return(%w[estimated_hours])
-      end
-
-      it "is invalid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to contain_exactly(:cant_be_inferior_to_remaining_work)
-      end
+      include_examples "contract is invalid", estimated_hours: :cant_be_inferior_to_remaining_work
     end
   end
 
-  describe "derived estimated hours" do
+  describe "total work (derived estimated hours)" do
     let(:changed_values) { [] }
     let(:attribute) { :derived_estimated_hours }
 
@@ -384,63 +366,47 @@
     end
   end
 
-  describe "remaining hours" do
+  describe "remaining work (remaining hours)" do
     before do
       work_package.estimated_hours = 5.0
+      work_package.clear_remaining_hours_change
       work_package.remaining_hours = remaining_hours
-
-      allow(work_package).to receive(:changed).and_return(%w[remaining_hours])
     end
 
-    context "when it's the same as estimated_hours" do
+    context "when it's the same as work" do
       let(:remaining_hours) { 5.0 }
 
-      it "is valid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:remaining_hours))
-          .to be_empty
-      end
+      include_examples "contract is valid"
     end
 
-    context "when it's less than estimated_hours" do
+    context "when it's less than work" do
       let(:remaining_hours) { 4.0 }
 
-      it "is valid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:remaining_hours))
-          .to be_empty
-      end
+      include_examples "contract is valid"
     end
 
-    context "when it's greater than estimated_hours" do
+    context "when it's greater than work" do
       let(:remaining_hours) { 6.0 }
 
-      it "is invalid" do
-        contract.validate
+      include_examples "contract is invalid", remaining_hours: :cant_exceed_work
+    end
 
-        expect(subject.errors.symbols_for(:remaining_hours))
-          .to contain_exactly(:cant_exceed_work)
-      end
+    context "when unset" do
+      let(:remaining_hours) { nil }
+
+      include_examples "contract is invalid", remaining_hours: :must_be_set_when_work_is_set
     end
   end
 
-  describe "estimated_hours and remaining_hours" do
-    context "when changing both and remaining_hours exceeds estimated_hours" do
+  describe "work and remaining work" do
+    context "when changing both and remaining work exceeds work" do
       before do
         work_package.estimated_hours = 5.0
         work_package.remaining_hours = 6.0
       end
 
-      it "is invalid" do
-        contract.validate
-
-        expect(subject.errors.symbols_for(:estimated_hours))
-          .to contain_exactly(:cant_be_inferior_to_remaining_work)
-        expect(subject.errors.symbols_for(:remaining_hours))
-          .to contain_exactly(:cant_exceed_work)
-      end
+      include_examples "contract is invalid", estimated_hours: :cant_be_inferior_to_remaining_work,
+                                              remaining_hours: :cant_exceed_work
     end
   end
 
diff --git a/spec/services/work_packages/set_attributes_service_spec.rb b/spec/services/work_packages/set_attributes_service_spec.rb
index 0d1f36d5f95c..6fedf2e13bd9 100644
--- a/spec/services/work_packages/set_attributes_service_spec.rb
+++ b/spec/services/work_packages/set_attributes_service_spec.rb
@@ -30,7 +30,7 @@
 
 RSpec.describe WorkPackages::SetAttributesService,
                type: :model do
-  shared_let(:status_no_pct_complete) { create(:status, default_done_ratio: nil, name: "no % complete") }
+  shared_let(:status_0_pct_complete) { create(:status, default_done_ratio: 0, name: "0% complete") }
   shared_let(:status_50_pct_complete) { create(:status, default_done_ratio: 50, name: "50% complete") }
   shared_let(:status_70_pct_complete) { create(:status, default_done_ratio: 70, name: "70% complete") }
 
@@ -43,7 +43,7 @@
     p
   end
   let(:work_package) do
-    wp = build_stubbed(:work_package, project:, status: status_no_pct_complete)
+    wp = build_stubbed(:work_package, project:, status: status_0_pct_complete)
     wp.type = initial_type
     wp.send(:clear_changes_information)
 
@@ -184,33 +184,25 @@
           it_behaves_like "service call", description: "recomputes remaining work accordingly"
         end
 
-        context "when another status with a default % complete value is set" do
+        context "when another status is set" do
           let(:call_attributes) { { status: status_70_pct_complete } }
           let(:expected_attributes) { { remaining_hours: 3.0 } }
 
           it_behaves_like "service call",
                           description: "recomputes remaining work according to the % complete value of the new status"
         end
-
-        context "when another status without any default % complete value is set" do
-          let(:call_attributes) { { status: status_no_pct_complete } }
-          let(:expected_attributes) { { remaining_hours: nil } }
-
-          it_behaves_like "service call",
-                          description: "unsets remaining work"
-        end
       end
 
-      context "given a work package with work and remaining work unset, and a status with no % complete" do
+      context "given a work package with work and remaining work unset, and a status with 0% complete" do
         before do
-          work_package.status = status_no_pct_complete
+          work_package.status = status_0_pct_complete
           work_package.done_ratio = work_package.status.default_done_ratio
           work_package.estimated_hours = nil
           work_package.remaining_hours = nil
           work_package.send(:clear_changes_information)
         end
 
-        context "when another status with a default % complete value is set" do
+        context "when another status with another % complete value is set" do
           let(:call_attributes) { { status: status_70_pct_complete } }
           let(:expected_attributes) { { remaining_hours: nil } }
 
@@ -220,10 +212,10 @@
 
         context "when work is set" do
           let(:call_attributes) { { estimated_hours: 10.0 } }
-          let(:expected_attributes) { { remaining_hours: nil } }
+          let(:expected_attributes) { { remaining_hours: 10.0 } }
 
           it_behaves_like "service call",
-                          description: "remaining work remains unset"
+                          description: "remaining work is updated accordingly from work and % complete value of the status"
         end
       end
     end
@@ -246,13 +238,6 @@
 
           it_behaves_like "service call", description: "sets the % complete value to the status default % complete value"
         end
-
-        context "when another status with no % complete value is set" do
-          let(:call_attributes) { { status: status_no_pct_complete } }
-          let(:expected_attributes) { { done_ratio: nil } }
-
-          it_behaves_like "service call", description: "unsets the % complete value"
-        end
       end
     end
 
@@ -261,8 +246,8 @@
       context "given a work package with work, remaining work, and % complete being set" do
         before do
           work_package.estimated_hours = 10.0
-          work_package.remaining_hours = 6.0
-          work_package.done_ratio = 40
+          work_package.remaining_hours = 3.0
+          work_package.done_ratio = 70
           work_package.send(:clear_changes_information)
         end
 
@@ -291,7 +276,7 @@
           # work changed by +10h
           let(:call_attributes) { { estimated_hours: 10.0 + 10.0 } }
           let(:expected_attributes) do
-            { remaining_hours: 6.0 + 10.0, done_ratio: 20 }
+            { remaining_hours: 3.0 + 10.0, done_ratio: 35 }
           end
 
           it_behaves_like "service call",
@@ -302,7 +287,7 @@
           # work changed by -2h
           let(:call_attributes) { { estimated_hours: 10.0 - 2.0 } }
           let(:expected_attributes) do
-            { remaining_hours: 6.0 - 2.0, done_ratio: 50 }
+            { remaining_hours: 3.0 - 2.0, done_ratio: 87 }
           end
 
           it_behaves_like "service call",
@@ -355,6 +340,14 @@
 
           it_behaves_like "service call", description: "updates % complete accordingly"
         end
+
+        context "when work is changed and remaining work is unset" do
+          let(:call_attributes) { { estimated_hours: 8.0, remaining_hours: nil } }
+          let(:expected_attributes) { { remaining_hours: 2.4 } } # would be 2.4000000000000004 without rounding
+          let(:expected_kept_attributes) { %w[done_ratio] }
+
+          it_behaves_like "service call", description: "% complete is kept and remaining work is recomputed (and rounded)"
+        end
       end
 
       context "given a work package with work and % complete being set, and remaining work being unset" do
@@ -481,6 +474,13 @@
 
           it_behaves_like "service call", description: "remaining work is set to the same value and % complete is set to 0%"
         end
+
+        context "when remaining work is set" do
+          let(:call_attributes) { { remaining_hours: 10.0 } }
+          let(:expected_attributes) { { estimated_hours: 10.0, done_ratio: 0 } }
+
+          it_behaves_like "service call", description: "work is set to the same value and % complete is set to 0%"
+        end
       end
     end
   end
diff --git a/spec/services/work_packages/update_ancestors_service_spec.rb b/spec/services/work_packages/update_ancestors_service_spec.rb
index 33ed8bf16756..05c495d178fb 100644
--- a/spec/services/work_packages/update_ancestors_service_spec.rb
+++ b/spec/services/work_packages/update_ancestors_service_spec.rb
@@ -56,9 +56,8 @@ def set_attributes_on(work_package, attributes)
 
   describe "done_ratio/estimated_hours/remaining_hours propagation" do
     context "when setting the status of a work package" do
-      shared_let(:open_status) { create(:status) }
-      shared_let(:new_status_with_done_ratio) { create(:status, default_done_ratio: 100) }
-      shared_let(:new_status_without_done_ratio) { create(:status, default_done_ratio: nil) }
+      shared_let(:open_status) { create(:status, name: "open", default_done_ratio: 0) }
+      shared_let(:complete_status_with_100p_done_ratio) { create(:status, name: "complete", default_done_ratio: 100) }
 
       context 'when using the "status-based" % complete mode',
               with_settings: { work_package_done_ratio: "status" } do
@@ -92,8 +91,8 @@ def call_update_ancestors_service(work_package)
                 it "recomputes child remaining work and update ancestors total % complete accordingly" do
                   value =
                     case field
-                    when :status then new_status_with_done_ratio
-                    when :status_id then new_status_with_done_ratio.id
+                    when :status then complete_status_with_100p_done_ratio
+                    when :status_id then complete_status_with_100p_done_ratio.id
                     end
                   set_attributes_on(child, field => value)
                   call_update_ancestors_service(child)
@@ -107,28 +106,6 @@ def call_update_ancestors_service(work_package)
               end
             end
           end
-
-          context "when changing child status to a status without any default done ratio" do
-            %i[status status_id].each do |field|
-              context "with the #{field} field" do
-                it "unsets child remaining work and update ancestors total % complete accordingly" do
-                  value =
-                    case field
-                    when :status then new_status_without_done_ratio
-                    when :status_id then new_status_without_done_ratio.id
-                    end
-                  set_attributes_on(child, field => value)
-                  call_update_ancestors_service(child)
-
-                  expect_work_packages([parent, child], <<~TABLE)
-                    | subject | work | total work | remaining work | total remaining work | % complete | total % complete |
-                    | parent  |  10h |        15h |            10h |                  10h |         0% |              33% |
-                    | child   |   5h |         5h |                |                      |            |                  |
-                  TABLE
-                end
-              end
-            end
-          end
         end
       end
     end