Hindu calendar follows the cycles of the Moon, and therefore there are around 29.5 days in a month. While there are 30 or 31 days in a Solar month. Hence, there is a difference of 11 days every year in both these calendars (Lunar and Solar) and this difference comes to 29 or 30 days in every 3 years, and becomes a whole month. To keep the lunar and solar calendars aligned, an extra month is added every three years. This extra month is known as Purushottam Maas since the main deity of this month is Lord Vishnu, who is also known as Lord Purushottam. This month is also known as Adhik Maas or Mal Maas.
In 2023, the Purushottam month is starting from Tuesday, 18th of July and ends on Wednesday, 16th of August, which falls in the month of Shravan. Therefore it is also called Shravan Purushottam Maas or Shravan Adhik Maas this year.
Purushottam Month is considered as a Holy month, and the benefits of this month are innumerable. The Puranas also sing high praises about Adhik Maas and indicate puja, readings of scriptures etc. during this month. Selfless actions, without any expectations of results are to be performed during Purushottam Maas. It is believed that a person can be bestowed with all the necessities of the life, as well as after leaving this world, he will be taken to the abode of Lord Krishna. The recitation of Srimad Bhagwat Purana and Bhagavad Gita during Adhik month is considered auspicious. Even the recitation of Lord Vishnu Sahastranaam Path during this month is considered highly beneficial.