Since April we've known that David Letterman is leaving The Late Show sometime next year.

Now, we know when. CBS made the announcement on Wednesday that May 20th, 2015 will be Dave's last night to host behind the Late Show desk. Stephen Colbert is taking over, however that date has not be announced.

“David Letterman has given to all of us a remarkable legacy of achievement and creative brilliance that will never be forgotten,” said CBS President Les Moonves in a statement. “It’s going to be tough to say goodbye, but I know we will all cherish the shows leading up to Dave’s final broadcast in May.”

There is history involved with the ending of Letterman hosting  The Late Show.

Letterman is currently the longest-running late night host on American TV, having begun on Feb. 1, 1982 as host of Late Night with David Letterman on NBC, which re-defined the genre for every generation thereafter. He jumped to CBS on Aug. 30, 1993 after NBC passed him over in favor of Jay Leno to succeed Johnny Carson as host of The Tonight Show.

The night he steps down, Letterman will have hosted 6,028 total episodes of both Late Night and The Late Show.

Also on CBS, Craig Ferguson's last broadcast as host of The Late Late Showafter 10 years is Dec. 19. British actor James Corden will make his debut as the show's host on March 9, 2015.