diff --git a/lib/atomic/accounts.ex b/lib/atomic/accounts.ex
index 6ce244d5e..4cb1af4b2 100644
--- a/lib/atomic/accounts.ex
+++ b/lib/atomic/accounts.ex
@@ -74,6 +74,7 @@ defmodule Atomic.Accounts do
       {:error, %Ecto.Changeset{}}
 
   """
+
   def register_user(attrs) do
     %User{}
     |> User.registration_changeset(attrs)
diff --git a/lib/atomic/accounts/collaborator_department.ex b/lib/atomic/accounts/collaborator_department.ex
new file mode 100644
index 000000000..5acdb542a
--- /dev/null
+++ b/lib/atomic/accounts/collaborator_department.ex
@@ -0,0 +1,29 @@
+defmodule Atomic.Accounts.CollaboratorDepartment do
+  @moduledoc """
+    A relation representing a collaborator who belongs to a department
+  """
+  use Atomic.Schema
+
+  alias Atomic.Departments.Department
+  alias Atomic.Accounts.User
+
+  @required_fields ~w(collaborator_id department_id)a
+
+  schema "collaborator_departments" do
+    belongs_to :collaborator, User
+    belongs_to :department, Department
+    timestamps()
+  end
+
+  def changeset(collaborator_departments, attrs) do
+    collaborator_departments
+    |> cast(attrs, @required_fields)
+    |> validate_required(@required_fields)
+  end
+
+  def create_changeset(collaborator_departments, attrs) do
+    collaborator_departments
+    |> cast(attrs, @required_fields)
+    |> validate_required(@required_fields)
+  end
+end
diff --git a/lib/atomic/accounts/user.ex b/lib/atomic/accounts/user.ex
index c86714ba5..7cfd22751 100644
--- a/lib/atomic/accounts/user.ex
+++ b/lib/atomic/accounts/user.ex
@@ -4,6 +4,8 @@ defmodule Atomic.Accounts.User do
   """
   use Atomic.Schema
 
+  alias Atomic.Accounts.CollaboratorDepartment
+
   alias Atomic.Accounts.Course
   alias Atomic.Activities.Enrollment
   alias Atomic.Organizations.{Membership, Organization}
@@ -24,8 +26,8 @@ defmodule Atomic.Accounts.User do
     belongs_to :course, Course
     field :profile_picture, ProfilePicture.Type
     field :role, Ecto.Enum, values: @roles
-
     has_many :enrollments, Enrollment
+    many_to_many :collaborators, User, join_through: CollaboratorDepartment, on_replace: :delete
 
     many_to_many :organizations, Organization, join_through: Membership
 
diff --git a/lib/atomic/departments/department.ex b/lib/atomic/departments/department.ex
index 8b9c4e01f..421a14900 100644
--- a/lib/atomic/departments/department.ex
+++ b/lib/atomic/departments/department.ex
@@ -3,7 +3,9 @@ defmodule Atomic.Departments.Department do
     A department of an organization
   """
   use Atomic.Schema
+  alias Atomic.Accounts.CollaboratorDepartment
   alias Atomic.Organizations.Organization
+  alias Atomic.Accounts.User
   alias Atomic.Activities.{Activity, ActivityDepartment}
 
   @required_fields ~w(name organization_id)a
@@ -12,7 +14,7 @@ defmodule Atomic.Departments.Department do
 
   schema "departments" do
     field :name, :string
-
+    many_to_many :collaborators, User, join_through: CollaboratorDepartment
     many_to_many :activities, Activity, join_through: ActivityDepartment, on_replace: :delete
 
     belongs_to :organization, Organization, on_replace: :delete_if_exists
diff --git a/priv/repo/migrations/20230114142351_create_collaborator_departments.exs b/priv/repo/migrations/20230114142351_create_collaborator_departments.exs
new file mode 100644
index 000000000..91809529f
--- /dev/null
+++ b/priv/repo/migrations/20230114142351_create_collaborator_departments.exs
@@ -0,0 +1,14 @@
+defmodule Atomic.Repo.Migrations.CreateCollaboratorDepartments do
+  use Ecto.Migration
+
+  def change do
+    create table(:collaborator_departments, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+
+      add :collaborator_id, references(:users, on_delete: :nothing, type: :binary_id)
+      add :department_id, references(:departments, on_delete: :nothing, type: :binary_id)
+
+      timestamps()
+    end
+  end
+end
diff --git a/priv/repo/seeds/accounts.exs b/priv/repo/seeds/accounts.exs
index a73986b84..1c980ae6b 100644
--- a/priv/repo/seeds/accounts.exs
+++ b/priv/repo/seeds/accounts.exs
@@ -1,6 +1,7 @@
 defmodule Atomic.Repo.Seeds.Accounts do
   alias Atomic.Accounts
   alias Atomic.Accounts.{Course, User}
+  alias Atomic.Accounts.User
   alias Atomic.Repo
 
   def run do
@@ -163,7 +164,7 @@ defmodule Atomic.Repo.Seeds.Accounts do
         "course_id" => Enum.random(courses).id
       }
 
-      case Accounts.register_user(user) do
+      case insert_user(user) do
         {:error, changeset} ->
           Mix.shell().error(Kernel.inspect(changeset.errors))