diff --git a/app/models/accounting_period.rb b/app/models/accounting_period.rb
index 1126b58df..a0377c1d7 100644
--- a/app/models/accounting_period.rb
+++ b/app/models/accounting_period.rb
@@ -37,7 +37,7 @@ class AccountingPeriod < ApplicationRecord
       vat_rate_group = {}
       i.invoice_items.each do |item|
         vat_type = item.invoice_item_type
-        vat_rate_group[vat_type] = vat_service.invoice_vat(item) / 100.0 unless vat_rate_group[vat_type]
+        vat_rate_group[vat_type] = vat_service.invoice_item_vat(item) / 100.0 unless vat_rate_group[vat_type]
       end
       { invoice: i, vat_rate: vat_rate_group }
     end
diff --git a/app/models/invoice_item.rb b/app/models/invoice_item.rb
index 4c5536fa4..7212a91f5 100644
--- a/app/models/invoice_item.rb
+++ b/app/models/invoice_item.rb
@@ -27,7 +27,7 @@ class InvoiceItem < Footprintable
   def net_amount
     # deduct VAT
     vat_service = VatHistoryService.new
-    vat_rate = vat_service.invoice_vat(self)
+    vat_rate = vat_service.invoice_item_vat(self)
     Rational(amount_after_coupon / (vat_rate / 100.00 + 1)).round.to_f
   end
 
@@ -36,19 +36,15 @@ class InvoiceItem < Footprintable
     amount_after_coupon - net_amount
   end
 
-  # return invoice item type (Matchine/Training/Space/Event/Subscription)
+  # return invoice item type (Machine/Training/Space/Event/Subscription) used to determine the VAT rate
   def invoice_item_type
     if object_type == Reservation.name
-      reservable_type = object.try(:reservable_type)
-      if reservable_type
-        return reservable_type
-      else
-        return ''
-      end
+      object.try(:reservable_type) || ''
     elsif object_type == Subscription.name
-      return Subscription.name
+      Subscription.name
+    else
+      ''
     end
-    ''
   end
 
   private
diff --git a/app/pdfs/pdf/invoice.rb b/app/pdfs/pdf/invoice.rb
index a4612ab3e..c96f5556c 100644
--- a/app/pdfs/pdf/invoice.rb
+++ b/app/pdfs/pdf/invoice.rb
@@ -233,7 +233,7 @@ class PDF::Invoice < Prawn::Document
       vat_rate_group = {}
       invoice.invoice_items.each do |item|
         vat_type = item.invoice_item_type
-        vat_rate_group[vat_type] = { vat_rate: vat_service.invoice_vat(item), total_vat: 0, amount: 0 } unless vat_rate_group[vat_type]
+        vat_rate_group[vat_type] = { vat_rate: vat_service.invoice_item_vat(item), total_vat: 0, amount: 0 } unless vat_rate_group[vat_type]
         vat_rate_group[vat_type][:total_vat] += item.vat
         vat_rate_group[vat_type][:amount] += item.amount.to_i
       end
diff --git a/app/services/vat_history_service.rb b/app/services/vat_history_service.rb
index 1beb048cf..9299a0172 100644
--- a/app/services/vat_history_service.rb
+++ b/app/services/vat_history_service.rb
@@ -2,8 +2,20 @@
 
 # Provides the VAT rate in use at the given date
 class VatHistoryService
+  # @return the VAT rate for the given Invoice
+  def invoice_vat(invoice)
+    vat_rate_group = {}
+    invoice.invoice_items.each do |item|
+      vat_type = item.invoice_item_type
+      vat_rate_group[vat_type] = { vat_rate: invoice_item_vat(item), total_vat: 0, amount: 0 } unless vat_rate_group[vat_type]
+      vat_rate_group[vat_type][:total_vat] += item.vat
+      vat_rate_group[vat_type][:amount] += item.amount.to_i
+    end
+    vat_rate_group
+  end
+
   # return the VAT rate for the given InvoiceItem
-  def invoice_vat(invoice_item)
+  def invoice_item_vat(invoice_item)
     if invoice_item.invoice.is_a?(Avoir)
       vat_rate(invoice_item.invoice.avoir_date, invoice_item.invoice_item_type)
     else
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 0b13ecc09..c6930d66d 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -105,7 +105,7 @@ class ActiveSupport::TestCase
 
     vat_service = VatHistoryService.new
     invoice.invoice_items.each do |item|
-      vat_rate = vat_service.invoice_vat(item)
+      vat_rate = vat_service.invoice_item_vat(item)
       if vat_rate.positive?
         computed_ht = sprintf('%.2f', (item.amount_after_coupon / (vat_rate / 100.00 + 1)) / 100.00).to_f