diff --git a/app/models/accounting_period.rb b/app/models/accounting_period.rb
index ed94691c8..48d2f66e4 100644
--- a/app/models/accounting_period.rb
+++ b/app/models/accounting_period.rb
@@ -47,10 +47,12 @@ class AccountingPeriod < ActiveRecord::Base
   end
 
   def vat_rate(date)
-    first_rate = vat_history.first
+    @vat_rates = vat_history if @vat_rates.nil?
+
+    first_rate = @vat_rates.first
     return first_rate[:rate] if date < first_rate[:date]
 
-    vat_history.each do |h|
+    @vat_rates.each do |h|
       return h[:rate] if h[:date] <= date
     end
   end
@@ -118,7 +120,7 @@ class AccountingPeriod < ActiveRecord::Base
 
   def compute_footprint
     columns = AccountingPeriod.columns.map(&:name)
-                              .delete_if { |c| %w[footprint updated_at].include? c }
+                              .delete_if { |c| %w[id footprint created_at updated_at].include? c }
 
     sha256 = Digest::SHA256.new
     sha256.hexdigest "#{columns.map { |c| self[c] }.join}#{previous_period ? previous_period.footprint : ''}"
diff --git a/app/validators/date_range_validator.rb b/app/validators/date_range_validator.rb
index cb6db1fe5..fccd59092 100644
--- a/app/validators/date_range_validator.rb
+++ b/app/validators/date_range_validator.rb
@@ -3,10 +3,10 @@
 # Validates that start_at is same or before end_at in the given record
 class DateRangeValidator < ActiveModel::Validator
   def validate(record)
-    the_end = record.start_at
-    the_start = record.end_at
-    return unless the_end.present? && the_end > the_start
+    the_end = record.end_at
+    the_start = record.start_at
+    return if the_end.present? && the_end >= the_start
 
-    record.errors[:end_at] << "The end date can't be before the start date. Pick a date after #{the_start}"
+    record.errors[:end_at] << I18n.t('errors.messages.end_before_start', START: the_start)
   end
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index d9c88a85a..b6fdb2374 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -40,6 +40,7 @@ en:
       cannot_encompass: "can't encompass an existing accounting period"
       in_closed_period: "can't be within a closed accounting period"
       invalid_footprint: "invoice's checksum is invalid"
+      end_before_start: "The end date can't be before the start date. Pick a date after %{START}"
 
   activemodel:
     errors:
diff --git a/config/locales/es.yml b/config/locales/es.yml
index 9a910571d..e1c9ae2b6 100644
--- a/config/locales/es.yml
+++ b/config/locales/es.yml
@@ -36,10 +36,11 @@ es:
       cannot_be_blank_at_same_time: "no puede estar vacío cuando %{field} también está vacío"
       cannot_be_in_the_past: "no puede estar en el pasado"
       cannot_be_before_previous_value: "No puede estar antes del valor anterior."
-      cannot_overlap: "can't overlap an existing accounting period"                        # missing translation
-      cannot_encompass: "can't encompass an existing accounting period"                    # missing translation
-      in_closed_period: "can't be within a closed accounting period"                       # missing translation
-      invalid_footprint: "invoice's checksum is invalid"                                   # missing translation
+      cannot_overlap: "can't overlap an existing accounting period"                               # missing translation
+      cannot_encompass: "can't encompass an existing accounting period"                           # missing translation
+      in_closed_period: "can't be within a closed accounting period"                              # missing translation
+      invalid_footprint: "invoice's checksum is invalid"                                          # missing translation
+      end_before_start: "The end date can't be before the start date. Pick a date after %{START}" # missing translation
 
   activemodel:
     errors:
diff --git a/config/locales/fr.yml b/config/locales/fr.yml
index 3df828a0e..2fea6427b 100644
--- a/config/locales/fr.yml
+++ b/config/locales/fr.yml
@@ -40,6 +40,7 @@ fr:
       cannot_encompass: "ne peut pas englober une période comptable existante"
       in_closed_period: "ne peut pas être dans une période comptable fermée"
       invalid_footprint: "la somme de contrôle de la facture est invalide"
+      end_before_start: "La date de fin ne peut pas être antérieure à la date de début. Choisissez une date après le %{START}"
 
   activemodel:
     errors:
diff --git a/config/locales/pt.yml b/config/locales/pt.yml
index 0cc6cf9c0..7a1b0111d 100755
--- a/config/locales/pt.yml
+++ b/config/locales/pt.yml
@@ -36,10 +36,11 @@ pt:
       cannot_be_blank_at_same_time: "Não pode ficar em branco quando %{field} estiver em branco também"
       cannot_be_in_the_past: "não pode ser no passado"
       cannot_be_before_previous_value: "não pode ser antes do valor anterior"
-      cannot_overlap: "can't overlap an existing accounting period"                        # missing translation
-      cannot_encompass: "can't encompass an existing accounting period"                    # missing translation
-      in_closed_period: "can't be within a closed accounting period"                       # missing translation
-      invalid_footprint: "invoice's checksum is invalid"                                   # missing translation
+      cannot_overlap: "can't overlap an existing accounting period"                               # missing translation
+      cannot_encompass: "can't encompass an existing accounting period"                           # missing translation
+      in_closed_period: "can't be within a closed accounting period"                              # missing translation
+      invalid_footprint: "invoice's checksum is invalid"                                          # missing translation
+      end_before_start: "The end date can't be before the start date. Pick a date after %{START}" # missing translation
 
   activemodel:
     errors: