Michelle Obama is celebrating her 50th birthday Friday.
The first lady is spending the day out of sight, with no public appearances after back-to-back White House events this week.
But she tweeted a picture of herself holding up her AARP card. She tweeted, quote, "Excited to join Barack" in the 50-plus club today. "check out my @AARP card!"
President Barack Obama turned 50 in 2011.
A birthday bash is on tap for Saturday night at the White House. The president has been involved in the planning.
Officials are keeping a lid on party details, but guests have been told to come prepared to dance.
Mrs. Obama said last month she wasn't certain how she would spend her birthday but that whatever she did might involve some dancing.
"There's one thing I can tell you for sure ... people will move," Valerie Jarrett, a senior White House adviser who is close to the Obamas, told The Associated Press.
Jarrett wouldn't comment on reports that Beyonce, who also is close to the Obama family, will sing at the first lady's party. Beyonce serenaded the Obamas as they danced at one of the balls for the president's first inauguration in 2009. Last year, she lip-synced to a pre-recorded voice track of the national anthem at Obama's second swearing-in ceremony at the Capitol.
Coincidentally, Beyonce's husband, rapper and entrepreneur Jay Z, is scheduled to bring his Magna Carter World Tour to Washington's Verizon Center on Thursday night, two days before Mrs. Obama's White House birthday blowout. That means Beyonce could be in town anyway.