Ultimateatomicbuster, Community a Wiki admin here. I did the research guys and it is seventeen years. This is a cut and pasted copy of the discontinuity I originally posted on an article page HERE:]:

Discontinuity: This episode retcons Jeff's age. It is possible he was lying the entire time, however this revalation conflicts with information in previous episodes as well as statements Community creator himself Dan Harmon had made early in the show's production about Jeff's age. Below are several "Community" episodes which hint at Jeff's age. "The Art of Discourse": Jeff is called "35" by Mark Cahill in 2010 and doesn't dispute it. This would later be contradicted. "Early 21st Century Romanticism": In 2011, Ben Chang steals Jeff's drivers license which clearly says "November 21, 1971" (this is actor Joel McHale's birthdate). On DVD commentaries for this episode and also in a tweet to a fan, Harmon dismissed this as a production error and suggested that Jeff was several years younger than him or Joel. At the time McHale was 40 and Harmon was 38. "Intro to Political Science": In 2011, a videotape of Jeff's audition for "The Real World: Seattle" is shown. Jeff says he was "like nineteen" when he recorded that tape. The Real World: Seattle premiered on June 16, 1998 and if it followed the production schedule of other Real World shows then it accepted audition tapes the previous year in 1997. This then suggests that Jeff was born around 1978. That put Jeff's age around 33-34 range back then and should make him 36-37 in Season Five. "Foosball and Nocturnal Vigilantism": Jeff claimed he was 10 years old when he met Shirley "Big Cheddar" who was 12 at the time. Either he was lying and he was older, and small for his age (14-15), or Shirley's age gets increased to 42. "Cooperative Escapism in Familial Relations": in 2012, Jeff very specifically tells his father he faked an appendectomy in seventh grade "22 years ago." The average age of a seventh grader is between 11-13, older if Jeff had failed a grade and was held back or younger if he skipped a grade (unlikely as it would probably be something he brag about). This is consistent with previous episodes as it places his age at that time to be around 34-35 which would make him 36-37 in Season Five. Additionally it's unlikely Jeff's could get away without lying about his age to his own father. Community writer and executive producer Andy Bobrow had a discussion with several fans on his twitter account about this discontinuity: “@Funkapus @SaraLinnLinn We try not to be sloppy. Try to make the characters as real as possible. Sometimes we screw up and everyone tells us”