app/views/categories/_form.html.erb
<%= form_for category do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :name %><br />
<%= f.text_field :name %>
</p>
<p>
<%= f.check_box :active %>
<%= f.label :active %>
</p>
<p>
<%= f.label "Billing Code" %><br />
<%= f.text_field :billing_code %>
</p>
<p><%= f.submit "Submit" %></p>
<% end %>