What configuration is required to use date_views with a field?
In addition to mapping 'handler' to 'date_views_filter_handler' you need to tell date_views that the field is a date:

function mymodule_views_data_alter(&amp;$data) {
  ...
  $data['mymodule_referral']['referred_at']['filter'] = array(
    'handler' =&gt; 'date_views_filter_handler',
    'is date' =&gt; TRUE,
  );
}


In the filter settings for referred_at you will now see referred_at as an option for "DATE FIELD(S)", and if you select it then it will work as expected.