It is based on the "Barah Maha" (Twelve Months), a composition composed by the Sikh gurus reflecting the changes in nature conveyed in the twelve-month cycle of the year.
The reference epoch of the Nanakshahi calendar is the birth of Guru Nanak Dev, corresponding to the year 1469 CE.
[2] The Nanakshahi Calendar is named after the founder of the Sikh religion, Guru Nanak Dev Ji.
[17] The epoch of this calendar is the birth of the first Sikh Guru, Nanak Dev in 1469 and the Nanakshahi year commences on 1 Chet.
The amended Nanakshahi calendar was adopted in 1998 and released in 1999 by the Shiromani Gurdwara Prabhandak Committee ("SGPC") to determine the dates for important Sikh events.
[24] The calendar was re-released in 2003 by the SGPC with three dates: Guru Nanak Dev Ji's Birth, Holla Mohalla, and Bandi Chhor Divas kept movable as per the old Bikrami system as a compromise.
Therefore, the calculations of this calendar do not regress back from 1999 CE into the Bikrami era, and accurately fixes for all time in the future.
[46] Pal Singh Purewal, as reported in the Edmonton Journal (March 2018) has stated that his aims in formulating the Nanakshahi calendar were, "first and foremost, it should respect sacred holy scriptures.
"[42] In reality however, state Haar and Kalsi (2009), the introduction of the Nanakshahi calendar has resulted in many festivals being "celebrated on two dates depending on the choice of the management of the local gurdwaras.
"[50] SGPC president, Gobind Singh Longowal, on 13 March 2018 urged all Sikhs to follow the current (2014) Nanakshahi calendar.
[51] The previous SGPC President before Longowal, Prof. Kirpal Singh Badungar, tried to appeal the Akal Takht to celebrate the birthday of Guru Gobind Singh on 23 Poh (5 January) as per the original Nanakshahi calendar, but the appeal was denied.
They argue that in the Bikrami calendar, dates of many gurpurbs coincide, thereby creating confusion among the Sikh Panth.
The Shiromani Gurdwara Prabandhak Committee had implemented and launched the copies of the Mool Nanakshahi Calendar on 14 April 2003 from the land of Takhat Sri Damdama Sahib under the presidency of prominent Sikh scholar Prof Kirpal Singh Badungar and Akal Takhat Jathedar Giani Joginder Singh Vedanti (chairman of the committee for Mool Nanakshahi Calendar) on the occasion of Baisakhi in the presence of large community gathering (unlike Bikrami calendar which is based on lunar setup the Mool Nanakshahi Calendar was largely based on solar system).
Sikhs throughout the world have embraced the Mool Nanakshahi Calendar with full reverence as the Sikh scholars with empirical research have held that the Calendar had its roots to the First Khalsa Raj established by Baba Banda Singh Bahadur who first released and implemented it.
[citation needed] The Sikh Youth of Punjab (SYP) embraces this version of the calendar.
[68] The extensive 2 day Mool Nanakshahi Calendar Implementation Conference in Chicago detailed the significance of the changes.