According to Vasishtha Siddhanta (the treatise of Vasishtha) Adhik Maas or the extra lunar month occurs after every 32 months, 16 days and 8 Ghatis (a Ghati is a period of 24 minutes and 60 Ghadts equal 24 hours). In this reference the concept of Adhika Maas is unique to the traditional Hindu lunar calendars.
A medium to adjust gap between Solar and Lunar Year
The solar year consists of 365 days and 06 hours approx. whereas the lunar year is of 354 days. Thus, the gap between solar and the lunar year is of around 11 days. The gap increases to approximate 1 month in three Lunar years. Hence, to balance the gap between solar and lunar calendar an extra month comes after every third year. It is termed as Adhik Maas or Mal mass or Purshotam Mass.
All auspicious activities like annaprashan, naam Karan, Grah Pravesh, marriage, mundane samskar, yagyopaveet, buying new valuables, entering new home are prohibited during this month. Hence, the month got its name as Mal Maas.
The legend behind this states, there were 12 lunar months and each was assigned to 1 god. Rishi-Munis calculated and facilitated Adhik Maas to balance solar and lunar years. Since it is Maal (unclean) Maas, therefore, no lord agreed to become the deity of the month. Lord Vishnu was then approached. Lord Vishnu took pity and assigned Adhik Maas to Himself. Hence, lord Vishnu is lord of this month and the month is called Purushottam Maas.
Purushottam means a man who is imbibed with all best qualities and this month is devoted to self-development, evaluation, assessment, reflection, retrospection and Introspection. It is a time for one's own soul and spirit to complete all pending work, detoxify the body that remains pending since last three years. It is month to regain once strength in physical, mental, emotional and spiritual terms. Hence, the month got its name purshottam Mass.
During each lunar month, Sun ingress into a new sign. During Adhik Maas, there is no Sun ingression or the Surya Sankranti. This is specific to Adhik Maas. The calculation of this month is purely based on the difference that takes place between the solar calendar and the lunar calendar.
As per legends, once Demon Hiranyakashipu had asked for a boon from lord Brahma that no man, animal, sura or asura should cause death to him; further he asked that he should not meet his death in any of the 12 months of the year, in the morning or at night, not inside the house nor outside it, neither by any weapon nor by any object. Bestowed with the boon, Demon Hiranyakashipu thought he had become immortal.
Later Demon Hiranyakashipu meet death at hands of Lord Narasimha who ripped his chest with the claws taking the form of half Lion and Half man , during Adhik Mass around sunset and at the threshold of the palace (neither inside nor outside). Therefore, during Adhik Maas no auspicious festive activity such as marriage, anushthan etc. are performed. Only naam japa, charity and Bhagavat katha, yagya is done.
Every individual has a spiritual entity that comprises up of 5 Bhootas - the air, water, earth, fire, and ether. These are manifested in the forms of the intellect- mind- ego- senses and the soul. One requires meditation to unite one's physical entity with that of the spiritual entity.
During Adhik mass naam japa, charity, Bhagavat katha and yagya is done by sadhak to gains Physical strength, mental balance, firmness of thought and actions, calmness and spiritual satisfaction. The main significance of Adhik Maas is associated with spiritual enlightenment and deliverance from earthly sins.
During the entire month of Adhik Maas along with fasting, yagya and havan reciting Shrimad Devi Bhagavatam, Shrimad Bhagwat puran, Shri Vishnu Puran, Bhavishyottar Puran are carried out by devotees. These acts of spirituality bring ample of religious merit and bring transformation for the better in individuals.
Any planetary doshaÃ¢ÂÂs in a horoscope can be regulated during this month by performing yagya and havan. It is believed that this month holds a special place in the Hindu religion and, therefore, rectifying planetary effects during this month give positive results 10 times better than performed during any other month.