Montgomery, 33, pleaded guilty in federal court in Manhattan in April 2007 to conspiracy to commit bank fraud and two counts of bank fraud in a counterfeit cheque scheme that also embroiled fellow sprinter and former partner Marion Jones, their former coach Steve Riddick and Charles Wells, their former sports agent.
Montgomery learned his fate at the United States Federal Court in White Plains, New York from US District Judge, the Hon Kenneth M Karas.
Attorneys for Montgomery had agreed with prosecutors that, having pleaded guilty, a sentence of between 37 to 46 months in prison was appropriate and he received the maximum jail time within those parameters.
The former sprinter was already behind bars, however, having been arrested on a separate indictment in Norfolk, Virginia, on April 30.
Montgomery was charged with conspiracy to possess with intent and to distribute more than 100g of heroin in the Eastern district of Virginia between 2007 and 2008.
Denied bail at a detention hearing last week in Norfolk, Montgomery faces a trial on those charges in July.
He retired from track and field in December 2005 in the wake of receiving a two-year doping ban, not for failing a drugs test but on the basis of an admission he gave about his use of steroids in 2001 in testimony to the BALCO investigation two years later.
His ban from the sport also brought with it an order to return his Olympic medals, a gold he won in the 4x100 relay in Sydney in 2000 and a silver in the 4x100 relay at the 1996 Games in Atlanta as well as a World Championship 100m silver medal in 2001.
Montgomery's world record-breaking 100m run of 9.78 seconds set in Paris in 2002 was also erased from the historical lists.
Jones, the mother of his son Tim Jr, also pleaded guilty last year to making false statements to investigators on the cheque-fraud case as well as lying to the BALCO grand jury about her own drug use.
She is serving a six-month prison sentence.