Like the Coptic calendar, the Ethiopic calendar has 12 months of 30 days plus 5 or 6 epagomenal days, which comprise a thirteenth month. The Ethiopian months begin on the same days as those of the Coptic calendar, but their names are in Ge'ez. A 6th epagomenal day is added every 4 years, without exception, on August 29 of the Julian calendar, 6 months before the corresponding Julian leap day. Thus the first day of the Ethiopian year, 1 Mäskäräm, for years between 1900 and 2099 (inclusive), is usually September 11 (Gregorian). However, it falls on September 12 in years before the Gregorian leap year.
A building in downtown Addis Ababa, Ethiopia, sports bunting in the Ethiopian national colors of green, yellow and red to mark the Ethiopian Millennium on 11 September 2007.
Enkutatash is the word for the Ethiopian New Year in Amharic, the official language of Ethiopia, while it is called Ri'se Awde Amet ("Head Anniversary") in Ge'ez, the term preferred by the Ethiopian & Eritrean Orthodox Tewahedo Churchs. It occurs on September 11th in the Gregorian Calendar; except for the year preceding a leap year, when it occurs on September 12th. The Ethiopian Calendar Year 1998 Amätä Məhrät ("Year of Mercy") began on the Gregorian Calendar Year on September 11th, 2005. However, the Ethiopian Years 1992 and 1996 began on the Gregorian Dates of 'September 12th 1999' and '2003' respectively.
This date correspondence applies for the Gregorian years 1900 to 2099. The Ethiopian leap year is every four without exception, while Gregorian centurial years are only leap years when exactly divisible by 400; thus a set of corresponding dates will most often apply for a single century. As the Gregorian year 2000 is a leap year, the current correspondence lasts two centuries instead.
The start of the Ethiopian year (Feast of El-Nayrouz) falls on August 29th or 30th (in the year just before the Julian leap year). This date corresponds to the Old-Style Julian Calendar; therefore, the start of the year has been transferred forward in the currently used Gregorian Calendar to September 11th or 12th (in the year just before the Julian leap year). This deviation between the Julian and the Gregorian Calendar will increase with the passing of the time. You can observe the real start date in the future centuries in a Gregorian to Ethiopian Date Converter.