Adhik Maas is extra lunar month in Hindu calendar and it is also known as Mal Maas, Purushottam Maas, Malimmacha and Londa Maas (लोंद मास). Adhik Maas concept is similar to leap day in English calendar. However, during Adhik Maas whole month in leaped in Hindu calendar. Adhik Maas occurs approximately every three years in Hindu calendar.
In the fixed cycle of Hindu months, the position of Adhik Maas is not fixed and it occurs randomly between any two months. In Hindu calendar, each Lunar month has single Sankranti point. During Sankranti, the sun moves from one zodiac to another and it happen only once during the entire span on the lunar month. However, those lunar months which are devoid of Sankranti are marked as Adhik Maas.
Adhik Maas is not good to perform any auspicious works. All auspicious works, including marriage ceremonies, house warming ceremonies, purchasing of new items, etc. are avoided during Adhik Maas in Hindu calendar. At the same time, Adhik Maas is very significant to perform austerity and it is dedicated to Lord Purushottam which is another form of Lord Vishnu.