diff --git a/app/models/invoice.rb b/app/models/invoice.rb
index d51533a77..6eb2e7bec 100644
--- a/app/models/invoice.rb
+++ b/app/models/invoice.rb
@@ -149,7 +149,7 @@ class Invoice < ActiveRecord::Base
     end
     # handle coupon
     unless avoir.coupon_id.nil?
-      discount = avoir.total  * avoir.coupon.percent_off / 100
+      discount = avoir.total  * avoir.coupon.percent_off / 100.0
       avoir.total -= discount
     end
     avoir
diff --git a/app/models/price.rb b/app/models/price.rb
index 932225408..e1c0988d7 100644
--- a/app/models/price.rb
+++ b/app/models/price.rb
@@ -114,7 +114,7 @@ class Price < ActiveRecord::Base
     # === apply Coupon if any ===
     unless coupon_code.nil?
       _coupon = Coupon.find_by_code(coupon_code)
-      _amount = _amount - (_amount  * _coupon.percent_off / 100)
+      _amount = _amount - (_amount  * _coupon.percent_off / 100.0)
     end
 
     # return result
diff --git a/app/models/reservation.rb b/app/models/reservation.rb
index a4ad7f0f9..946ef44ae 100644
--- a/app/models/reservation.rb
+++ b/app/models/reservation.rb
@@ -132,7 +132,7 @@ class Reservation < ActiveRecord::Base
       total = invoice.invoice_items.map(&:amount).map(&:to_i).reduce(:+)
       invoice_items << Stripe::InvoiceItem.create(
           customer: user.stp_customer_id,
-          amount: -(total  * cp.percent_off / 100),
+          amount: -(total  * cp.percent_off / 100.0),
           currency: Rails.application.secrets.stripe_currency,
           description: "coupon #{cp.code}"
       )
@@ -394,7 +394,7 @@ class Reservation < ActiveRecord::Base
 
     unless coupon_code.nil?
       cp = Coupon.find_by_code(coupon_code)
-      total = total - (total  * cp.percent_off / 100)
+      total = total - (total  * cp.percent_off / 100.0)
       self.invoice.coupon_id = cp.id
     end
 
diff --git a/app/models/subscription.rb b/app/models/subscription.rb
index 5717a1dce..558d217d0 100644
--- a/app/models/subscription.rb
+++ b/app/models/subscription.rb
@@ -39,7 +39,7 @@ class Subscription < ActiveRecord::Base
             total = plan.amount
             Stripe::InvoiceItem.create(
                 customer: user.stp_customer_id,
-                amount: -(total  * cp.percent_off / 100),
+                amount: -(total  * cp.percent_off / 100.0),
                 currency: Rails.application.secrets.stripe_currency,
                 description: "coupon #{cp.code}"
             )
@@ -136,7 +136,7 @@ class Subscription < ActiveRecord::Base
     unless coupon_code.nil?
       coupon = Coupon.find_by_code(coupon_code)
       coupon_id = coupon.id
-      total = plan.amount - (plan.amount * coupon.percent_off / 100)
+      total = plan.amount - (plan.amount * coupon.percent_off / 100.0)
     end
 
     invoice = Invoice.new(invoiced_id: id, invoiced_type: 'Subscription', user: user, total: total, stp_invoice_id: stp_invoice_id, coupon_id: coupon_id)
diff --git a/app/pdfs/pdf/invoice.rb b/app/pdfs/pdf/invoice.rb
index decc83f54..21c4689df 100644
--- a/app/pdfs/pdf/invoice.rb
+++ b/app/pdfs/pdf/invoice.rb
@@ -141,7 +141,7 @@ module PDF
         # subtract the coupon, if any
         unless invoice.coupon_id.nil?
           cp = invoice.coupon
-          discount = total_calc  * cp.percent_off / 100
+          discount = total_calc  * cp.percent_off / 100.0
           total_calc = total_calc - discount
 
           # add a row for the coupon
diff --git a/app/services/statistic_service.rb b/app/services/statistic_service.rb
index 968bd8c91..e5d0f3f8c 100644
--- a/app/services/statistic_service.rb
+++ b/app/services/statistic_service.rb
@@ -121,10 +121,14 @@ class StatisticService
   def subscriptions_list(options = default_options)
     result = []
     InvoiceItem.where('invoice_items.created_at >= :start_date AND invoice_items.created_at <= :end_date', options)
-      .eager_load(subscription: [:plan, user: [:profile, :group]]).each do |i|
+      .eager_load(invoice: [:coupon], subscription: [:plan, user: [:profile, :group]]).each do |i|
         unless i.invoice.is_a?(Avoir)
           sub = i.subscription
           if sub
+            ca = i.amount.to_i / 100.0
+            unless i.invoice.coupon_id.nil?
+              ca = ca - ( ca * i.invoice.coupon.percent_off / 100.0 )
+            end
             u = sub.user
             p = sub.plan
             result.push OpenStruct.new({
@@ -138,7 +142,7 @@ class StatisticService
               duration: p.duration.to_i,
               subscription_id: sub.id,
               invoice_item_id: i.id,
-              ca: i.amount.to_i / 100.0
+              ca: ca
             }.merge(user_info(u)))
           end
         end
@@ -337,6 +341,7 @@ class StatisticService
   def calcul_ca(invoice)
     return nil unless invoice
     ca = 0
+    # sum each items in the invoice (+ for invoices/- for refunds)
     invoice.invoice_items.each do |ii|
       unless ii.subscription_id
         if invoice.is_a?(Avoir)
@@ -346,6 +351,11 @@ class StatisticService
         end
       end
     end
+    # subtract coupon discount from invoices and refunds
+    unless invoice.coupon_id.nil?
+      ca = ca - ( ca * invoice.coupon.percent_off / 100.0 )
+    end
+    # divide the result by 100 to convert from centimes to monetary unit
     ca == 0 ? ca : ca / 100.0
   end
 
@@ -354,6 +364,10 @@ class StatisticService
     invoice.invoice_items.each do |ii|
       ca = ca - ii.amount.to_i
     end
+    # subtract coupon discount from the refund
+    unless invoice.coupon_id.nil?
+      ca = ca - ( ca * invoice.coupon.percent_off / 100.0 )
+    end
     ca == 0 ? ca : ca / 100.0
   end