Indira Ekadasi is observed in the Hindu month of Ashwin (North Indian) or Bhadrapada month. This Ekadashi falls during the Pitru Paksha. As per the vrat katha mentioned in the Brahmavaivarta Purana, Indira Ekadasi is observed for fore-fathers.
Every Ekadasi fast is dedicated to get moksha for ourselves this Ekadashi is solely dedicated to provide salvation to our dead ancestors.
How to obsereve Indira Ekadashi fast and what are the merits or benefits of Ekadasi fast
On this Ekadashi, complete fast or upvaas is kept. Devotees worship Lord Vishnu to give moksha to their dead ancestors. They perform Jagran in the night and spend their time with Vishnu naam Jaap. Upavaas is broken on Dwadashi day by taking meal with family.
Indira Ekadashi vrat gives devotee the result of Ashwamedha Yaga (Horse Sacrifice). Thus, Indira Ekadashi is very significant and important than other Ekadashi vrat.