Answer by taking a quote from the following article:

Joe Jackson Gibbs (born November 25, 1940) is a former American football coach, current NASCAR Championship team owner, and former NHRA team owner. He was the 20th and 26th head coach in the history of the Washington Redskins (1981-1992, 2004-2007). Well known for his long hours and work ethic, Gibbs constructed what Steve Sabol has called, "The most diverse dynasty in NFL history", building championship teams with many players who have had mediocre to average careers while playing for other NFL teams. During his first stint in the National Football League, he coached the Redskins for 12 seasons and led them to eight playoff appearances, four NFC Championship titles, and three Super Bowl titles.

Throughout his retirement, many NFL owners approached Gibbs hoping to lure him out of retirement, but to no avail. Some owners even offered to move his entire NASCAR racing team to their team's city if he came back. The only team he seriously considered coming back for was the Carolina Panthers when they first joined the NFL as an expansion in 1995. However, he did not believe he would be able to manage his time between his race team and coaching. In 1999, he was part of a group that was trying to buy the Redskins but ultimately failed. In 2002, Gibbs and a small group of investors bought five percent of the Atlanta Falcons from owner Arthur Blank for $27 million. It wasn't until late 2003 when Gibbs really started to catch the football fever again. Blank and his general manager, Rich McKay moved quickly to interview him for the Falcons' vacant head coaching position due to the firing of Dan Reeves. However, when Gibbs found out that Steve Spurrier resigned as the Redskins' head coach, they realized that even though Gibbs was one of the team's minority owners, his loyalty still lies with the Redskins. It is well documented that Daniel Snyder had been turned down by Gibbs several times before. On December 31, 2003, Snyder's private plane (Redskin One) was spotted at an airport outside of Charlotte, North Carolina. After spending 11 years in retirement from the NFL, Snyder successfully lured Gibbs out of retirement. Gibbs' change of heart was quite a surprise to the football and NASCAR worlds. During his January 7 press conference, a visibly emotional Snyder welcomed him back. Gibbs then stated that even though he enjoyed NASCAR immensely, he had missed coaching in the NFL. And although he had fielded offers in the past, he could only see himself coaching for the Redskins. Because of his credibility, Gibbs was able to assemble one of the largest and most experienced coaching staffs in the NFL. Many coaches from his previous tenure with the team returned with Gibbs as well, including offensive line coach/assistant head coach Joe Bugel, offensive coordinator Don Breaux, quarterbacks coach Jack Burns, and tight ends coach Rennie Simmons. Gibbs was able to lure former Buffalo Bills head coach Gregg Williams to join the Redskins to run the defense and hired one of his former running backs, Ernest Byner to serve as running backs coach. Overall, many of his assistant and position coaches were either former head coaches and/or held top assistant coaching positions with other NFL teams. Gibbs left his racing team in the hands of his eldest son, J.D., while his other son, Coy, joined him as an assistant with the Redskins.

When did he rejoin the redskins?
2003