A Florida court ruled the 60-year-old must surrender to the Bureau of Prisons by April 1 and that his sentence be followed by two years of supervised release and 200 hours of community service.
Thorpe must also make efforts to repay the tax while on supervised release. He pleaded guilty in September.
The golfer played more than 450 tournaments on the PGA Tour and had three top-10 finishes in majors -- two in the U.S. Open and one in the U.S. PGA Championship.
He has won 13 times, including one major, in more than 300 events on the senior Champions Tour.
Thorpe has more than $13 million in career earnings as a professional golfer, according to the PGA Tour website.
Prosecutors said that for 2002, 2003 and 2004, Thorpe did not file an individual tax return until after he was confronted by special agents of the Internal Revenue Service (IRS).
According to court documents, the amount of unreported income for the three years was $5.36 million and the tax loss was $2.06 million.
(Reporting by Simon Evans in Miami, editing by Tony Jimenez)