diff --git a/stoptime.rb b/stoptime.rb
index 407cdcb..ebe0c78 100644
--- a/stoptime.rb
+++ b/stoptime.rb
@@ -193,6 +193,7 @@ module StopTime::Models
   # [email] email address (String)
   # [phone] phone number (String)
   # [hourly_rate] default hourly rate (Float)
+  # [time_specification] whether the customer requires time specifications (TrueClass/FalseClass)
   # [created_at] time of creation (Time)
   # [updated_at] time of last update (Time)
   #
@@ -358,6 +359,8 @@ module StopTime::Models
   # [id] unique identification number (Fixnum)
   # [number] invoice number (Fixnum)
   # [paid] flag whether the invoice has been paid (TrueClass/FalseClass)
+  # [include_specification] flag whether the invoice should include a time
+  #                         specification (TrueClass/FalseClass)
   # [created_at] time of creation (Time)
   # [updated_at] time of last update (Time)
   #
@@ -694,6 +697,18 @@ module StopTime::Models
     end
   end
 
+  class TimeSpecificationSupport < V 1.95 # :nodoc:
+    def self.up
+      add_column(Customer.table_name, :time_specification, :boolean)
+      add_column(Invoice.table_name, :include_specification, :boolean)
+    end
+
+    def self.down
+      remove_column(Customer.table_name, :time_specification)
+      remove_column(Invoice.table_name, :include_specification)
+    end
+  end
+
 end # StopTime::Models
 
 # = The Stop… Camping Time! controllers
@@ -836,6 +851,7 @@ module StopTime::Controllers
         attrs.each do |attr|
           @customer[attr] = @input[attr]
         end
+        @customer.time_specification = @input.has_key? "time_specification"
         @customer.save
         if @customer.invalid?
           @errors = @customer.errors
@@ -1040,6 +1056,7 @@ module StopTime::Controllers
       invoice = Invoice.create(:number => number)
       invoice.customer = Customer.find(customer_id)
       invoice.company_info = CompanyInfo.last
+      invoice.include_specification = invoice.customer.time_specification
 
       # Handle the hourly rated tasks first by looking at the selected time
       # entries.
@@ -1127,6 +1144,7 @@ module StopTime::Controllers
     def post(customer_id, invoice_number)
       invoice = Invoice.find_by_number(invoice_number)
       invoice.paid = @input.has_key? "paid"
+      invoice.include_specification = @input.has_key? "include_specification"
       invoice.save
 
       redirect R(CustomersNInvoicesX, customer_id, invoice_number)
@@ -1804,6 +1822,12 @@ module StopTime::Views
           _form_input_with_label("Phone number", "phone", :tel)
           _form_input_with_label("Financial contact", "financial_contact", :text)
           _form_input_with_label("Default hourly rate", "hourly_rate", :text)
+          div.control_group do
+            label.control_label "Time specifications?"
+            div.controls do
+              _form_input_checkbox("time_specification")
+            end
+          end
           div.form_actions do
             button.btn.btn_primary @button.capitalize, :type => "submit",
               :name => @button, :value => @button.capitalize
@@ -2018,6 +2042,12 @@ module StopTime::Views
               _form_input_checkbox("paid")
             end
           end
+          div.control_group do
+            label.control_label "Include specification?"
+            div.controls do
+              _form_input_checkbox("include_specification")
+            end
+          end
           div.form_actions do
             button.btn.btn_primary "Update", :type => :submit,
               :name => "update", :value => "Update"
diff --git a/templates/invoice.tex.erb b/templates/invoice.tex.erb
index cdc2692..aacabee 100644
--- a/templates/invoice.tex.erb
+++ b/templates/invoice.tex.erb
@@ -1,4 +1,4 @@
-\documentclass[a4paper,12pt,oneside,dutch]{isodoc}
+\documentclass[a4paper,oneside,dutch]{isodoc}
 
 % rubber: clean <%= @number %>.out
 
@@ -61,6 +61,8 @@
 <% end %><% unless @company.vatno.blank? %>  vatno=<%= @company.vatno %>,
 <% end %><% unless @company.chamber.blank? %>  chamber=<%= @company.chamber %>
 <% end %>}
+\setlength{\parindent}{0pt}
+\setlength{\parskip}{\medskipamount}
 
 <% if @company.bank_name.present? %>
 \renewcommand{\accountnotext}{<%= @company.bank_name %> rekeningnr}
@@ -88,6 +90,13 @@
 \newcommand{\ihtotal}[1]{\cmidrule[.05em]{4-4}%
   \textbf{\totaltext}&&&\textbf{\currency~#1}}
 
+\newenvironment{istable}%
+ {\vskip1em\tabularx{\linewidth}{@{}X@{\quad}l@{\qquad}r@{}}
+   \descriptiontext&Datum&Aantal uur\ML}%
+ {\endtabularx}
+\newcommand{\istask}[1]{\textbf{#1}\\}
+\newcommand{\isitem}[3]{\quad #1&#2&#3\\}
+
 \begin{document}
 
 \invoice{
@@ -122,10 +131,34 @@
  \end{ihtable}
  \vspace{2em}
 
+<% if @invoice.include_specification?
+%>  Zie bijlage op de volgende pagina voor een nadere specificatie.\\[1em]<%end %>
  Ik verzoek u vriendelijk het verschuldigde bedrag binnen 30 dagen na
  factuurdatum over te maken onder vermelding van het factuurnummer. \\
 
  \accountdata
 }
 
+<% if @invoice.include_specification? %>{
+ \newpage
+
+ {\bfseries\scshape\Large Specificatie}
+
+ Hieronder volgt een specificatie van gemaakte uren per taak per
+ uitgevoerde activiteit.
+
+ \begin{istable}
+ <% @invoice.tasks.each do |task|
+%> \istask{<%= task.comment_or_name %>}<%
+      task.time_entries.each do |time_entry| %>
+  \isitem{<%= time_entry.comment || "Geen opmerking" %>}%
+         {<%= time_entry.date.to_date %>}%
+         {<%= number_with_precision(time_entry.hours_total) %>}<%
+      end %>\\[\medskipamount]<%
+    end %>
+ \end{istable}
+ \label{LastPageOf\thelettercount}
+<% end %>}
+\letter{}
+
 \end{document}