In Hindu calendar 2015 (2015-2016), there is an Adhik Maas (Mala Maas, Adhika Masam). It is an extra month according to lunar calendar.
2015-2016 Hindu calendar Year is known as Manmadha Nama Samvatsara. ‘Ashada Masam’ comes twice in 2015, one is Nija Ashada Masam and the another one is Adhika Ashada Masam.
As per North Indian Hindi calendars, Adhika Masam begins on June 17 and ends on July 16.
In Gujarati, Marathi, Kannada & Telugu calendars also, Adhika Masam is from June 17 to July 16 in 2015.
It is to note that Adhik Month is dedicated to Lord Krishna. Adhik Maas is also referred to as Mala Maasa or Purushottama Maasa.
Why Adhik Month comes?
A lunar year has 354 days while a solar year has 365 days. This means, at the rate of 11 days a year, in the course of 2 years 8 months, the difference is 29 and a half days equal to a lunar month. Therefore every 33rd month is considered an ‘Adhika Masa.
In practice, the speeds of the Sun and Moon can cause the Adhika Masa to be between the 28th and 36th months. ‘Adhika Masa (also called ‘Mala masa and ‘Purshotthama masa) is not followed in Assam, Bengal, Kerala, Odisha and Tamil Nadu since they follow the 365 day calendar and it is Solar Calendar (Sauramana Panchangam).