In Hindu calendar 2018 (2018-2019), there is an Adhik Maas (Mala Maas, Adhika Masam). It is an extra month according to lunar calendar.
2018-2019 Hindu calendar Year is known as Vilambi Nama Samvatsara. ‘Jyeshta Masam’ comes twice in 2018, one is Adhika Jyeshta Masam and the another one is Nija Jyeshta Masam.
As per North Indian Hindi calendars, Adhika Masam begins on May 16 and ends on June 13. In Gujarati, Marathi, Kannada & Telugu calendars, Adhika Masam is from May 16 to June 13, 2018.
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).