Legend Behind Purushottam Maas (Adhik Maas) :
In Hindu Calendar, each of the 12 months are ruled by 12 different Deities. But the Adhik Maas or Extra month was not ruled by any God and for which, he was called Mal Maas (unclean month). Due to which, Adhik Maas felt bad and took his plight to Lord Vishnu and prayed to Lord Vishnu to seek his refuge and help. Lord Hari heard his plea and assigned himself to Adhik Maas, and gave him the name of "Purushottam Maas". Lord Vishnu also said that the significance of Japa, Homa, Vrat, Katha and other Good deeds done during the Purushottam Maas will be more fruitful than the prayers and good deeds done during the other 12 months.
It is said that ages ago, King Nahush was freed from all bondages by keeping the Adhik Mass vrat and got the throne of Lord Indra, who was the king of Heaven.
Apart from this, once Goddess Lakshmi asked Sri Hari Lord Vishnu the procedure of performing Adhik Maas Puja. Lord Vishnu replied that he is the Lord of Adhik Maas and named it Purushottam Month, and therefore by doing Good deeds and virtues like Japa, Homa, Vrat will help to bring most fruitful results.
Significance of Purushottam Maas or Adhik Maas :