diff --git a/lib/putzplan/tasks/completed_task.ex b/lib/putzplan/tasks/completed_task.ex
index 9d16520..980853f 100644
--- a/lib/putzplan/tasks/completed_task.ex
+++ b/lib/putzplan/tasks/completed_task.ex
@@ -11,6 +11,14 @@ defmodule Putzplan.Tasks.CompletedTask do
     attribute :completion, :date do
       allow_nil? false
     end
+
+    attribute :user_id, :uuid do
+      allow_nil? false
+    end
+
+    attribute :task_id, :uuid do
+      allow_nil? false
+    end
   end
 
   relationships do
diff --git a/lib/putzplan/tasks/task.ex b/lib/putzplan/tasks/task.ex
index aed1bb8..1e647db 100644
--- a/lib/putzplan/tasks/task.ex
+++ b/lib/putzplan/tasks/task.ex
@@ -19,6 +19,10 @@ defmodule Putzplan.Tasks.Task do
     repo Putzplan.Repo
   end
 
+  relationships do
+    has_many :completed_tasks, Putzplan.Tasks.CompletedTask
+  end
+
   # Attributes are the simple pieces of data that exist on your resource
   attributes do
     # Add an autogenerated UUID primary key called `:id`.
diff --git a/priv/repo/migrations/20250405121515_add_completed_tasks.exs b/priv/repo/migrations/20250405121515_add_completed_tasks.exs
new file mode 100644
index 0000000..d5fb261
--- /dev/null
+++ b/priv/repo/migrations/20250405121515_add_completed_tasks.exs
@@ -0,0 +1,13 @@
+defmodule Putzplan.Repo.Migrations.AddCompletedTasks do
+  use Ecto.Migration
+
+  def change do
+    create table(:completed_tasks, primary_key: false) do
+      add :id, :uuid, primary_key: true, null: false
+      add :completion, :date, null: false
+
+      add :user_id, references(:users), null: false
+      add :task_id, references(:tasks), null: false
+    end
+  end
+end