Civil calendar

The civil calendar is the calendar, or possibly one of several calendars, used within a country for civil, official, or administrative purposes. The civil calendar is almost always used for general purposes by people and private organizations.
The most widespread civil calendar and "de facto" international standard is the Gregorian calendar. Although that calendar is associated with the Catholic Church and the papacy, it has been adopted, as a matter of convenience, by many secular and non-Christian countries although some countries use other calendars.
Civil calendars worldwide.
The majority of countries in the world use the Gregorian calendar as their sole civil calendar. 
Countries which do not use the Gregorian calendar include Afghanistan and Iran (which use the Solar Hijri calendar), Ethiopia (Ethiopian calendar), and Nepal (Vikram Samvat). 
Some countries use other calendars alongside the Gregorian calendar: these include Saudi arabia (Islamic calendar), Bangladesh (Bangla calendar), India (Indian national calendar), and Israel (Hebrew calendar).
Other countries use modified versions of the Gregorian calendar, such as Taiwan (Minguo calendar), Thailand (Thai solar calendar), North Korea (North Korean Calendar) and Japan (Japanese calendar).