thumb|right|The Gazette of India is dated in both the Gregorian calendar and the Indian national calendar.
The Indian national calendar, also called the Shaka calendar or Śaka calendar, is a solar calendar that is used alongside the Gregorian calendar by The Gazette of India, in news broadcasts by All India Radio, and in calendars and official communications issued by the Government of India. It was adopted in 1957 following the recommendation of the Calendar Reform Committee.
Śaka Samvat is generally 78 years behind the Gregorian calendar, except from January–March, when it is behind by 79 years.
Calendar structure
The calendar months follow the signs of the tropical zodiac rather than the sidereal zodiac normally used with the Hindu and Buddhist calendars.
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! Name The official calendar reckoned by the government of India has Sunday as the first and Saturday as the last day of the week.
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History
Senior Indian Astrophysicist Meghnad Saha was the head of the Calendar Reform Committee under the aegis of the Council of Scientific and Industrial Research.
It was Saha's effort which led to the formation of the committee in 1952. The task before the committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India. The committee had to undertake a detailed study of thirty different calendars prevalent in different parts of the country. The task was further complicated by the integration of those calendars with religion and local sentiments.
In 1954 the committee recommended a fixed tropical solar calendar for use as a unified national civil calendar, which was adopted as the Indian national calendar. A tropical lunisolar calendar was also proposed for religious purposes but this recommendation was not accepted.
India's first prime minister, Jawaharlal Nehru, in his preface to the Report of the committee, published in 1955, wrote:
: "They (different calendars) represent past political divisions in the country ... . Now that we have attained Independence, it is obviously desirable that there should be a certain uniformity in the calendar for our civic, social, and other purposes, and this should be done on a scientific approach to this problem."
Usage started officially on 1 Chaitra 1879 Saka Era, or 22 March 1957. However, despite the government's attempts to propagate the calendar through official Rashtriya Panchangs, the Indian national calendar did not find acceptance with panchang makers or the general public, and current usage is largely limited to governmental offices. Existing calendars based on the Saka era remain in use, which can lead to confusion.