In a move that will complete the generational transition in latenight, David Letterman is preparing to retire from CBS next year.

Letterman, who will turn 67 on April 12, disclosed his decision during Thursday afternoon’s taping of “The Late Show.”

“The man who owns this network, Leslie Moonves, he and I have had a relationship for years and years and years, and we have had this conversation in the past, and we agreed that we would work together on this circumstance and the timing of this circumstance. And I phoned him just before the program, and I said ‘Leslie, it’s been great, you’ve been great, and the network has been great, but I’m retiring,’” Letterman said.

“I just want to reiterate my thanks for the support from the network, all of the people who have worked here, all of the people in the theater, all the people on the staff, everybody at home, thank you very much. What this means now, is that Paul and I can be married.

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“We don’t have the timetable for this precisely down – I think it will be at least a year or so, but sometime in the not too distant future, 2015 for the love of God, in fact, Paul and I will be wrapping things up.”

Afterward, Letterman received a standing ovation from the audience at the Ed Sullivan Theater.

Sources said there was no creative license in Letterman’s statement. CBS Corp. chief Moonves got the official word from Letterman on his decision to retire shortly before Thursday’s taping.

“When Dave decided on a one-year extension for his most recent contract, we knew this day was getting closer, but that doesn’t make the moment any less poignant for us,” Moonves said in a statement.

“For 21 years, David Letterman has graced our network’s air in late night with wit, gravitas and brilliance unique in the history of our medium. During that time, Dave has given television audiences thousands of hours of comedic entertainment, the sharpest interviews in late night, and brilliant moments of candor and perspective around national events. He’s also managed to keep many celebrities, politicians and executives on their toes – including me.

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“There is only one David Letterman. His greatness will always be remembered here, and he will certainly sit among the pantheon of this business. On a personal note, it’s been a privilege to get to know Dave and to enjoy a terrific relationship. It’s going to be tough to say goodbye. Fortunately, we won’t have to do that for another year or so. Until then, we look forward to celebrating Dave’s remarkable show and incredible talents,” Moonves said.

Last year, Letterman re-upped his contract with the Eye that ran through mid-2014 with a one-year term that signaled he was starting to think about calling it a wrap. However, sources close to the situation advised that Letterman may stick around a little bit longer past the August expiration of his current contract.

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As of next year, Letterman will have hosted “Late Show” on CBS for 22 years. He logged 11 years as host of NBC’s “Late Night” before famously being passed over at NBC for Johnny Carson’s throne on “The Tonight Show” — over Carson’s objection. Letterman has logged more than 6,000 episodes during his long career. The combination of his NBC and CBS runs makes him the longest-serving latenight host in history, surpassing Carson’s 30-year tenure.

Word of Letterman’s plan spread quickly via Twitter on Thursday afternoon after musician Mike Mills, who appears on Thursday’s show, noted Letterman’s big news following the taping.

Dave just announced his retirement #2015 #muchlovedave — Mike Mills (@m_millsey) April 3, 2014

Letterman’s departure will cap a busy period of host shuffling in latenight following Jay Leno’s retirement from “The Tonight Show” in February, which made way for Jimmy Fallon to take the helm on Feb. 17.

Staying on through 2015 will allow Letterman to comfortably outlast his longtime rival, although Leno had the ratings advantage during most of his 22-year run on NBC. Sources close to the situation were also adamant that the decision was Letterman’s, with no nudge from CBS despite the fact that he is now going up against much younger competitors on NBC and ABC.

With Letterman stepping down, the latenight TV landscape will be dominated by hosts (Fallon, Jimmy Kimmel, Seth Meyers, Craig Ferguson, Jon Stewart, Stephen Colbert, Conan O’Brien) who came of age professionally in the post-Johnny Carson era. Arsenio Hall, who returned to latenight this past fall with a syndicated series, is the lone exception.

In fact, Letterman is the bigger influence on his contemporary crop of rivals. ABC’s Kimmel has made no secret of idolizing his 11:35 p.m. competitor.

David @Letterman is the best there is and ever was. — Jimmy Kimmel (@jimmykimmel) April 3, 2014

Hall was equally effusive: “I have had the unique pleasure of watching him as a fan and competing against him as a fellow host. He has set a standard for comedy in late night that I strive to achieve every single day,” he said.

Confirmation of Letterman’s retirement raises the question about his successor. Ferguson has hosted “The Late Late Show” following Letterman since 2005, but it’s not clear if CBS sees him as 11:35 p.m. successor potential. CBS reps would not comment on succession questions Thursday, emphasizing that today’s news was “all about Dave.”

Ferguson has been in contract talks with CBS in recent months as his current deal is believed to expire later this year. He has a clause in his contract that calls for him to either succeed Letterman or command a form of payout from CBS. Ferguson has stepped up his activity outside of “The Late Late Show” as a producer and as talent in the past few years. He’s set to debut this fall as host of the syndicated gameshow strip “Celebrity Name Game,” from distributor Debmar-Mercury.

Since his start on CBS in 1993, Letterman has owned both “The Late Show” and “The Late Late Show,” which was first hosted by Tom Snyder and then Craig Kilborn prior to Ferguson. He has the contractual right to control the show that follows his at 12:37 p.m., and it is believed that Letterman and his Worldwide Pants production banner may still have some measure of involvement in CBS’ latenight lineup even after his retirement.

Owning his show has given Letterman an unusual degree of control over his destiny at CBS — a welcome change after his unhappy exit from NBC. “The Late Show” has also made him very rich. At one point he was said to have commanded an annual paycheck of about $30 million, though his salary has been downsized some in his last few contracts.