When does United States of Tara return?

United States of Tara is an American comedy drama television series. The series follows the life of Tara Gregson, a suburban artist and mother coping with dissociative identity disorder. Toni Collette won the 2009 Primetime Emmy Award and 2010 Golden Globe Award for Best Actress in a Comedy Series for her role. The show's third and final season premiered on March 28, 2011. Showtime announced that the series would not be renewed for a fourth season.