Indira Ekadashi occurs during the waning phase of moon in the month of Ashwin (September – October) in traditional North Indian calendar. In 2015, Indira Ekadasi is on October 8. The importance of Indira Ekadasi is described in the Brahmavaivarta Purana and was described by Lord Krishna to Yudhisthira. It is believed that observing this Ekadasi will help in removing the sins committed by oneself and one’s forefathers. The Ekadasi falls during the Pitru Paksh Shradh period in North India. Ekadashi fasting is dedicated to Lord Vishnu.

Legend has it that King Indrasena on Narada Muni’s advice observed Indira Ekadasi and saved his father from the remorse of sins committed during earthly life.

Indira Ekadasi falls during the Pitru Paksh Shradh period inNorth India.

Prayers and rituals are performed in the name of forefathers and dead relatives on the day before Indira Ekadasi. A single meal is only eaten on the day before Ekadashi. A complete fast is observed on the Indira Ekadashi day by staunch devotees. In the afternoon on the Ekadasi day, some people perform rituals dedicated to the dead.

The fasting of Indira Ekadasi ends on the next day and is broken by having food with family members.

Source – http://www.hindu-blog.com/2008/09/indira-ekadasi.html