diff --git a/app/graphql/mutations/customers/create.rb b/app/graphql/mutations/customers/create.rb
index d4e0a49c722..0975a835be8 100644
--- a/app/graphql/mutations/customers/create.rb
+++ b/app/graphql/mutations/customers/create.rb
@@ -18,7 +18,7 @@ class Create < BaseMutation
       def resolve(**args)
         result = ::Customers::CreateService
           .new(context[:current_user])
-          .create(**args.merge(organization_id: current_organization.id))
+          .create(**args.merge(organization_id: current_organization.id, billing_entity_id: current_organization.billing_entities.first.id))
 
         result.success? ? result.customer : result_error(result)
       end
diff --git a/app/models/billing_entity.rb b/app/models/billing_entity.rb
index 16e896884f1..0dbb1e16c2e 100644
--- a/app/models/billing_entity.rb
+++ b/app/models/billing_entity.rb
@@ -36,7 +36,7 @@ class BillingEntity < ApplicationRecord
   has_one :salesforce_integration, class_name: "Integrations::SalesforceIntegration"
 
   # this one needs to be done via applied_dunning_campaign_id
-  has_one :applied_dunning_campaign
+  has_one :applied_dunning_campaign, class_name: "DunningCampaign", foreign_key: :applied_dunning_campaign_id
 
   has_many :invoice_custom_section_selections
   has_many :selected_invoice_custom_sections, through: :invoice_custom_section_selections, source: :invoice_custom_section
diff --git a/app/models/customer.rb b/app/models/customer.rb
index d41687f3287..c8daded9d99 100644
--- a/app/models/customer.rb
+++ b/app/models/customer.rb
@@ -35,6 +35,7 @@ class Customer < ApplicationRecord
   before_save :ensure_slug
 
   belongs_to :organization
+  belongs_to :billing_entity
   belongs_to :applied_dunning_campaign, optional: true, class_name: "DunningCampaign"
 
   has_many :subscriptions
@@ -142,7 +143,7 @@ def applicable_net_payment_term
   def applicable_invoice_custom_sections
     return [] if skip_invoice_custom_sections?
 
-    selected_invoice_custom_sections.order(:name).presence || organization.selected_invoice_custom_sections.order(:name)
+    selected_invoice_custom_sections.order(:name).presence || billing_entity.selected_invoice_custom_sections.order(:name)
   end
 
   def editable?
diff --git a/app/models/error_detail.rb b/app/models/error_detail.rb
index ec87a980e68..31393572de3 100644
--- a/app/models/error_detail.rb
+++ b/app/models/error_detail.rb
@@ -7,6 +7,7 @@ class ErrorDetail < ApplicationRecord
 
   belongs_to :owner, polymorphic: true
   belongs_to :organization
+  belongs_to :billing_entity
 
   ERROR_CODES = %w[not_provided tax_error tax_voiding_error]
   enum :error_code, ERROR_CODES
@@ -16,22 +17,24 @@ class ErrorDetail < ApplicationRecord
 #
 # Table name: error_details
 #
-#  id              :uuid             not null, primary key
-#  deleted_at      :datetime
-#  details         :jsonb            not null
-#  error_code      :integer          default("not_provided"), not null
-#  owner_type      :string           not null
-#  created_at      :datetime         not null
-#  updated_at      :datetime         not null
-#  organization_id :uuid             not null
-#  owner_id        :uuid             not null
+#  id                :uuid             not null, primary key
+#  deleted_at        :datetime
+#  details           :jsonb            not null
+#  error_code        :integer          default("not_provided"), not null
+#  owner_type        :string           not null
+#  created_at        :datetime         not null
+#  updated_at        :datetime         not null
+#  billing_entity_id :uuid
+#  organization_id   :uuid             not null
+#  owner_id          :uuid             not null
 #
 # Indexes
 #
-#  index_error_details_on_deleted_at       (deleted_at)
-#  index_error_details_on_error_code       (error_code)
-#  index_error_details_on_organization_id  (organization_id)
-#  index_error_details_on_owner            (owner_type,owner_id)
+#  index_error_details_on_billing_entity_id  (billing_entity_id)
+#  index_error_details_on_deleted_at         (deleted_at)
+#  index_error_details_on_error_code         (error_code)
+#  index_error_details_on_organization_id    (organization_id)
+#  index_error_details_on_owner              (owner_type,owner_id)
 #
 # Foreign Keys
 #
diff --git a/app/models/integrations/base_integration.rb b/app/models/integrations/base_integration.rb
index 6b97dec6bb2..436b01dc233 100644
--- a/app/models/integrations/base_integration.rb
+++ b/app/models/integrations/base_integration.rb
@@ -11,6 +11,7 @@ class BaseIntegration < ApplicationRecord
     INTEGRATION_ACCOUNTING_TYPES = %w[Integrations::NetsuiteIntegration Integrations::XeroIntegration].freeze
 
     belongs_to :organization
+    belongs_to :billing_entity
 
     has_many :integration_items, dependent: :destroy, foreign_key: :integration_id
     has_many :integration_resources, dependent: :destroy, foreign_key: :integration_id
diff --git a/app/models/invoice.rb b/app/models/invoice.rb
index c990cb8354c..94ef56c932c 100644
--- a/app/models/invoice.rb
+++ b/app/models/invoice.rb
@@ -11,11 +11,13 @@ class Invoice < ApplicationRecord
   CREDIT_NOTES_MIN_VERSION = 2
   COUPON_BEFORE_VAT_VERSION = 3
 
-  before_save :ensure_organization_sequential_id, if: -> { organization.per_organization? && !self_billed }
+  # before_save :ensure_organization_sequential_id, if: -> { organization.per_organization? && !self_billed }
+  before_save :ensure_billing_entity_sequential_id, if: -> { billing_entity.per_entity? && !self_billed }
   before_save :ensure_number
 
   belongs_to :customer, -> { with_discarded }
   belongs_to :organization
+  belongs_to :billing_entity
 
   has_many :fees
   has_many :credits
@@ -353,7 +355,8 @@ def document_invoice_name
     return I18n.t("invoice.self_billed.document_name") if self_billed?
     return I18n.t('invoice.prepaid_credit_invoice') if credit?
 
-    if %w[AU AE ID NZ].include?(organization.country)
+    # if %w[AU AE ID NZ].include?(organization.country)
+    if %w[AU AE ID NZ].include?(billing_entity.country)
       return I18n.t('invoice.paid_tax_invoice') if advance_charges?
       return I18n.t('invoice.document_tax_name')
     end
@@ -374,62 +377,62 @@ def void_invoice!
   end
 
   def ensure_number
-    self.number = "#{organization.document_number_prefix}-DRAFT" if number.blank? && !status_changed_to_finalized?
+    self.number = "#{billing_entity.document_number_prefix}-DRAFT" if number.blank? && !status_changed_to_finalized?
 
     return unless status_changed_to_finalized?
 
-    if organization.per_customer? || self_billed
+    if billing_entity.per_customer? || self_billed
       # NOTE: Example of expected customer slug format is ORG_PREFIX-005
-      customer_slug = "#{organization.document_number_prefix}-#{format("%03d", customer.sequential_id)}"
+      customer_slug = "#{billing_entity.document_number_prefix}-#{format("%03d", customer.sequential_id)}"
       formatted_sequential_id = format('%03d', sequential_id)
 
       self.number = "#{customer_slug}-#{formatted_sequential_id}"
     else
-      org_formatted_sequential_id = format('%03d', organization_sequential_id)
-      formatted_year_and_month = Time.now.in_time_zone(organization.timezone || 'UTC').strftime('%Y%m')
+      org_formatted_sequential_id = format('%03d', billing_entity_sequential_id)
+      formatted_year_and_month = Time.now.in_time_zone(billing_entity.timezone || 'UTC').strftime('%Y%m')
 
-      self.number = "#{organization.document_number_prefix}-#{formatted_year_and_month}-#{org_formatted_sequential_id}"
+      self.number = "#{billing_entity.document_number_prefix}-#{formatted_year_and_month}-#{org_formatted_sequential_id}"
     end
   end
 
-  def ensure_organization_sequential_id
-    return if organization_sequential_id.present? && organization_sequential_id.positive?
+  def ensure_billing_entity_sequential_id
+    return if billing_entity_sequential_id.present? && billing_entity_sequential_id.positive?
     return unless status_changed_to_finalized?
 
-    self.organization_sequential_id = generate_organization_sequential_id
+    self.billing_entity_sequential_id = generate_billing_entity_sequential_id
   end
 
-  def generate_organization_sequential_id
-    timezone = organization.timezone || 'UTC'
-    organization_sequence_scope = organization.invoices.with_generated_number.where(
+  def generate_billing_entity_sequential_id
+    timezone = billing_entity.timezone || 'UTC'
+    billing_entity_sequence_scope = billing_entity.invoices.with_generated_number.where(
       "date_trunc('month', created_at::timestamptz AT TIME ZONE ?)::date = ?",
       timezone,
       Time.now.in_time_zone(timezone).beginning_of_month.to_date
     ).non_self_billed
 
     result = Invoice.with_advisory_lock(
-      organization_id,
+      billing_entity_id,
       transaction: true,
       timeout_seconds: 10.seconds
     ) do
       # If previous invoice had different numbering, base sequential id is the total number of invoices
-      organization_sequential_id = if switched_from_customer_numbering?
-        organization.invoices.non_self_billed.with_generated_number.count
+      billing_entity_sequential_id = if switched_from_customer_numbering?
+        billing_entity.invoices.non_self_billed.with_generated_number.count
       else
-        organization
+        billing_entity
           .invoices
           .non_self_billed
-          .where.not(organization_sequential_id: 0)
-          .order(organization_sequential_id: :desc)
+          .where.not(billing_entity_sequential_id: 0)
+          .order(billing_entity_sequential_id: :desc)
           .limit(1)
-          .pick(:organization_sequential_id) || 0
+          .pick(:billing_entity_sequential_id) || 0
       end
 
       # NOTE: Start with the most recent sequential id and find first available sequential id that haven't occurred
       loop do
-        organization_sequential_id += 1
+        billing_entity_sequential_id += 1
 
-        break organization_sequential_id unless organization_sequence_scope.exists?(organization_sequential_id:)
+        break billing_entity_sequential_id unless billing_entity_sequence_scope.exists?(billing_entity_sequential_id:)
       end
     end
 
@@ -440,11 +443,11 @@ def generate_organization_sequential_id
   end
 
   def switched_from_customer_numbering?
-    last_invoice = organization.invoices.non_self_billed.order(created_at: :desc).with_generated_number.first
+    last_invoice = billing_entity.invoices.non_self_billed.order(created_at: :desc).with_generated_number.first
 
     return false unless last_invoice
 
-    last_invoice&.organization_sequential_id&.zero?
+    last_invoice&.billing_entity_sequential_id&.zero?
   end
 
   def status_changed_to_finalized?
diff --git a/app/models/organization.rb b/app/models/organization.rb
index 18df63cf193..60f3c49aec9 100644
--- a/app/models/organization.rb
+++ b/app/models/organization.rb
@@ -10,6 +10,7 @@ class Organization < ApplicationRecord
     "credit_note.created"
   ].freeze
 
+  has_many :billing_entities
   has_many :api_keys
   has_many :memberships
   has_many :users, through: :memberships
diff --git a/app/services/customers/create_service.rb b/app/services/customers/create_service.rb
index e20c16472f2..bb530cdfe46 100644
--- a/app/services/customers/create_service.rb
+++ b/app/services/customers/create_service.rb
@@ -32,6 +32,7 @@ def create_from_api(organization:, params:)
 
       ActiveRecord::Base.transaction do
         customer.name = params[:name] if params.key?(:name)
+        customer.billing_entity_id = params[:billing_entity_id] if params.key?(:billing_entity_id)
         customer.country = params[:country]&.upcase if params.key?(:country)
         customer.address_line1 = params[:address_line1] if params.key?(:address_line1)
         customer.address_line2 = params[:address_line2] if params.key?(:address_line2)
@@ -142,6 +143,7 @@ def create(**args)
 
       customer = Customer.new(
         organization_id: args[:organization_id],
+        billing_entity_id: args[:billing_entity_id],
         external_id: args[:external_id],
         name: args[:name],
         country: args[:country]&.upcase,
diff --git a/app/services/error_details/create_service.rb b/app/services/error_details/create_service.rb
index 951d96b6800..0305a1b174c 100644
--- a/app/services/error_details/create_service.rb
+++ b/app/services/error_details/create_service.rb
@@ -15,6 +15,7 @@ def create_error_details!
       new_error = ErrorDetail.create!(
         owner:,
         organization:,
+        billing_entity:,
         error_code: params[:error_code],
         details: params[:details]
       )
diff --git a/app/services/invoices/add_on_service.rb b/app/services/invoices/add_on_service.rb
index bc98bdd1110..efc2292ae61 100644
--- a/app/services/invoices/add_on_service.rb
+++ b/app/services/invoices/add_on_service.rb
@@ -14,6 +14,7 @@ def create
       ActiveRecord::Base.transaction do
         invoice = Invoice.create!(
           organization: customer.organization,
+          billing_entity: customer.billing_entity,
           customer:,
           issuing_date:,
           payment_due_date:,
@@ -94,7 +95,7 @@ def payment_due_date
 
     def should_deliver_email?
       License.premium? &&
-        customer.organization.email_settings.include?('invoice.finalized')
+        customer.billing_entity.email_settings.include?('invoice.finalized')
     end
   end
 end
diff --git a/app/services/invoices/advance_charges_service.rb b/app/services/invoices/advance_charges_service.rb
index a5ade782fde..158c3ae85de 100644
--- a/app/services/invoices/advance_charges_service.rb
+++ b/app/services/invoices/advance_charges_service.rb
@@ -8,6 +8,7 @@ def initialize(initial_subscriptions:, billing_at:)
 
       @customer = initial_subscriptions&.first&.customer
       @organization = customer&.organization
+      @billing_entity = customer&.billing_entity
       @currency = initial_subscriptions&.first&.plan&.amount_currency
 
       super
@@ -35,12 +36,12 @@ def call
 
     private
 
-    attr_accessor :initial_subscriptions, :billing_at, :customer, :organization, :currency
+    attr_accessor :initial_subscriptions, :billing_at, :customer, :organization, :billing_entity, :currency
 
     def subscriptions
-      return [] unless organization
+      return [] unless billing_entity
 
-      @subscriptions ||= organization.subscriptions.where(
+      @subscriptions ||= billing_entity.subscriptions.where(
         external_id: initial_subscriptions.pluck(:external_id).uniq,
         status: [:active, :terminated]
       )
diff --git a/app/services/invoices/apply_taxes_service.rb b/app/services/invoices/apply_taxes_service.rb
index 2a85824a1dd..c6c55cb3de4 100644
--- a/app/services/invoices/apply_taxes_service.rb
+++ b/app/services/invoices/apply_taxes_service.rb
@@ -52,9 +52,10 @@ def call
     attr_reader :invoice
 
     delegate :organization, to: :invoice
+    delegate :billing_entity, to: :invoice
 
     def applicable_taxes
-      organization.taxes.where(id: indexed_fees.keys)
+      billing_entity.taxes.where(id: indexed_fees.keys)
     end
 
     # NOTE: indexes the invoice fees by taxes.
diff --git a/app/services/invoices/create_generating_service.rb b/app/services/invoices/create_generating_service.rb
index 4cc02e60c01..55248400778 100644
--- a/app/services/invoices/create_generating_service.rb
+++ b/app/services/invoices/create_generating_service.rb
@@ -21,6 +21,7 @@ def call
         invoice = Invoice.create!(
           id: invoice_id || SecureRandom.uuid,
           organization:,
+          billing_entity:,
           customer:,
           invoice_type:,
           currency:,
@@ -45,6 +46,7 @@ def call
     attr_accessor :customer, :invoice_type, :currency, :datetime, :charge_in_advance, :skip_charges, :invoice_id
 
     delegate :organization, to: :customer
+    delegate :billing_entity, to: :customer
 
     # NOTE: accounting date must be in customer timezone
     def issuing_date
diff --git a/app/services/invoices/create_pay_in_advance_charge_service.rb b/app/services/invoices/create_pay_in_advance_charge_service.rb
index 8b6e32c5d3d..a03c2ec7124 100644
--- a/app/services/invoices/create_pay_in_advance_charge_service.rb
+++ b/app/services/invoices/create_pay_in_advance_charge_service.rb
@@ -107,7 +107,7 @@ def deliver_webhooks
     end
 
     def should_deliver_email?
-      License.premium? && customer.organization.email_settings.include?('invoice.finalized')
+      License.premium? && customer.billing_entity.email_settings.include?('invoice.finalized')
     end
 
     def wallet
@@ -151,6 +151,7 @@ def create_error_detail(code)
       error_result = ErrorDetails::CreateService.call(
         owner: invoice,
         organization: invoice.organization,
+        billing_entity: invoice.billing_entity,
         params: {
           error_code: :tax_error,
           details: {
diff --git a/app/services/invoices/subscription_service.rb b/app/services/invoices/subscription_service.rb
index b0d8a401dc6..f9d87f8aec1 100644
--- a/app/services/invoices/subscription_service.rb
+++ b/app/services/invoices/subscription_service.rb
@@ -139,7 +139,7 @@ def set_invoice_generated_status
 
     def should_deliver_finalized_email?
       License.premium? &&
-        customer.organization.email_settings.include?("invoice.finalized")
+        customer.billing_entity.email_settings.include?("invoice.finalized")
     end
 
     def flag_lifetime_usage_for_refresh
diff --git a/db/migrate/20250131093431_add_references_to_billing_entities.rb b/db/migrate/20250131093431_add_references_to_billing_entities.rb
index ca5838f12dd..906825b4ec5 100644
--- a/db/migrate/20250131093431_add_references_to_billing_entities.rb
+++ b/db/migrate/20250131093431_add_references_to_billing_entities.rb
@@ -16,5 +16,6 @@ def change
     add_reference :cached_aggregations, :billing_entity, index: {algorithm: :concurrently}, type: :uuid
     add_reference :data_exports, :billing_entity, index: {algorithm: :concurrently}, type: :uuid
     add_reference :invoice_custom_section_selections, :billing_entity, index: {algorithm: :concurrently}, type: :uuid
+    add_reference :error_details, :billing_entity, index: {algorithm: :concurrently}, type: :uuid
   end
 end
diff --git a/db/migrate/20250131111555_populate_billing_entity_for_organizations.rb b/db/migrate/20250131111555_populate_billing_entity_for_organizations.rb
index e83f22ae5dc..43661e7f990 100644
--- a/db/migrate/20250131111555_populate_billing_entity_for_organizations.rb
+++ b/db/migrate/20250131111555_populate_billing_entity_for_organizations.rb
@@ -62,7 +62,7 @@ def change
       organization.cached_aggregations.update_all(billing_entity_id: billing_entity.id)
       organization.data_exports.update_all(billing_entity_id: billing_entity.id)
       organization.invoice_custom_section_selections.update_all(billing_entity_id: billing_entity.id)
-
+      ErrorDetail.where(organization_id: organization.id).update_all(billing_entity_id: billing_entity.id)
 
       organization.taxes.applied_to_organization.each do |tax|
         billing_entity.taxes << tax
diff --git a/db/schema.rb b/db/schema.rb
index bbb0d956200..cfc35350fdf 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -640,6 +640,8 @@
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "error_code", default: 0, null: false
+    t.uuid "billing_entity_id"
+    t.index ["billing_entity_id"], name: "index_error_details_on_billing_entity_id"
     t.index ["deleted_at"], name: "index_error_details_on_deleted_at"
     t.index ["error_code"], name: "index_error_details_on_error_code"
     t.index ["organization_id"], name: "index_error_details_on_organization_id"