The Thai solar calendar, Suriyakati (Thai: สุริยคติ), has been the official and prevalent calendar in Thailand since 1888, although the Western calendar is sometimes used in business, and quite often in banking. In 1941 (2484 B.E.) as World War II loomed on the horizon, Prime Minister Phibunsongkhram per decree made January 1 the official start of a new year (so year 2483 B.E. had only nine months). When converting a date prior to that year, check whether it falls between January 1 and March 31: if so the number to add or subtract is 542, not 543. Image:Ad Be.png