Adhika Masam is an additional month that appears once
in 2-3 years in the Hindu lunar calendar. This implies that
a year with Adhika Masam will have 13 months in place of
12 months.The main deity of this month is Lord Vishnu,
who is worshiped as ‘Purushottama’ and therefore this
month is also known as ‘Purushottama Masam’.
The Hindu calendar is based on the cycle of moon and
therefore consists of 354 days whereas the solar calendar
consists of 365 days in a year.The difference of days(11 days)
between the lunar and solar calendar over a period of 2-3 years
makes up a full month of nearly 29 days. This month is then
observed as Adhika Masam. It should therefore be understood
that Adhika Masam will never occur in the solar calendar
followed in the States of West Bengal. Orissa, Tamilnadu,
Assam and Kerala. The observance of this additional month
is therefore restricted to States that follow lunar calendar
calculations like Maharashtra, Gujarat, Karnataka and Andhra
Pradesh. Special rituals are held in various temples in these
States during the period of Adhika Masam.
During the Adhika Masa period, marriages, house warming
ceremonies, buying new ornaments or vehicles are prohibited.
Installation of new idols of God in temples,any form of fire
related rituals like Yajna, any vrat associated to Goddess and
devotees on a first time pilgrimage are prohibited.
Functions that can be performed are–worship of Lord Vishnu,
Sandhya Vandanam, Ekadasi Vrut and baby shower ceremony,
Rituals related to Dosha Nivaarana Puja,Chaturmasa vrut and
Shraddha Karma or offering to the ancestors can be performed.