The holidays for 2014 are:
Jan. 1- New Year's Day
Jan 12- Zanzibar Revolution Day (The President decided on Jan 11th that since the 12th fell on a Sunday this year that the 13th would be a national holiday. Schools that tried to open, there were police there to tell them they HAD to close this day. ) This day commemorates the day in 1964 when Zanzibar overthrew it's Arab government (Oman).
Jan 13- Birth of the Prophet Muhammad
April 21- Easter Monday
April 26- Union Day
May 1- Labor Day
July 7- Saba Saba (Literally "seven seven") International Trade Fair Day
July 28- Eid al-Fitr (End of Ramadan)
Aug 8- Nane Nane (Literally "eight eight") Farmer's Day- There is a week long fair in Arusha, like a county fair
Oct 4- Eid al Adha or Feast of Sacrifice (Muslims remember the day that Abraham obeyed God to sacrifice his son Ishmael but a goat was substituted instead.)
Oct 14- Nyerere Day- Honoring Tanzania's first president, and remembering the day of his death.
Dec 9-Independance Day- The day British government handed over independence to Tanzania in 1963
Dec 25- Christmas Day
Dec 26- Boxing Day
exact dates were obtained from: http://www.worldtravelguide.net/tanzania/public-holidays