It's no small matter. Her high-low fashion choices mix everyday, off-the-rack fare with custom creations from top designers whose gowns can run into five figures.
In recent weeks, Mrs. Obama has turned heads with a forest-green Naeem Khan dress at the opening of a new costume gallery at New York's Metropolitan Museum of Art. She shimmered in a silver Marchesa gown at the White House Correspondents' Association Dinner. And her flowered shirtdress for a Mother's Day tea at the White House (recycled from an earlier event) hit the just right note for an audience of military moms.
It takes money to pull that off, month after month. Those three dresses by themselves could add up to more than $15,000 retail, not to mention accessories such as shoes and jewelry.
Is it the taxpayers who foot the bill? No. (Despite what critics say.)
Is it Mrs. Obama? Usually, but not always.
Does she pay full price? Not likely.
Does she ever borrow gowns from designers? No.
The financing of the first lady's wardrobe is something that the Obama White House is loath to discuss. It's a subject that has bedeviled presidents and their wives for centuries. First ladies are expected to dress well, but the job doesn't come with a clothing allowance or a salary.
Mary Todd Lincoln racked up tens of thousands of dollars in clothing bills and considered selling manure from the White House grounds to pay them off, according to the National First Ladies' Library. Jacqueline Kennedy's father-in-law stepped in to finance her Oleg Cassini wardrobe to keep clothes from becoming a political liability for President John Kennedy. Nancy Reagan got grief for borrowing designer gowns and not always returning them or reporting them as gifts.
Laura Bush, in her memoir, said she was "amazed by the sheer number of designer clothes that I was expected to buy" as first lady.
How does Mrs. Obama, a fashion icon with far more expensive tastes than Mrs. Bush, swing it?
For starters, the Obamas reported adjusted income of $481,000 last year, and assets worth $1.8 million to $7 million.
And like most people, Mrs. Obama (mostly her personal aide, really) looks for discounts.
And, for really big events, the first lady has an option not available to every fashionista.
Here's how Joanna Rosholm, press secretary to the first lady, explains it:
"Mrs. Obama pays for her clothing. For official events of public or historic significance, such as a state visit, the first lady's clothes may be given as a gift by a designer and accepted on behalf of the U.S. government. They are then stored by the National Archives."
That saves Mrs. Obama considerable money, although the White House refused to say how often the first lady wears donated clothes and the National Archives declined to say how many such items it has in storage. The White House did say that the first lady doesn't borrow any clothing and, for the most part, buys her own clothes.
The clothing donated by designers includes Mrs. Obama's two inaugural gowns made by Jason Wu, a lesser-known designer before Mrs. Obama turned him into a star in the fashion firmament. Wu declined to discuss how he works with the first lady.
Mrs. Obama and Wu both were there when the first inaugural gown was presented to the Smithsonian in March 2010. The first lady said in her remarks: "The dress I donated today, made by Jason Wu, is a masterpiece." But the Smithsonian lists the gown as a "gift of Jason Wu in honor of first lady" Michelle Obama, making clear it came from him. The first lady's office had no comment on that.
Two other examples of gowns worn by the first lady that were donated by designers: the blue Carolina Herrera gown that Mrs. Obama wore to February 's state dinner for French President Francois Hollande and the gold beaded Naeem Khan gown that Mrs. Obama wore to the 2012 governors ball, now on display at the American Museum of Natural History. Herrera and Khan declined comment.
The first lady's office had no comment on whether the couture gowns worn by Mrs. Obama for her six other White House state dinners also were donated. Nor would it say how many gowns have been donated for the array of other big events for which the first lady is expected to appear in couture finery, such as the annual Kennedy Center Honors ceremonies, governors' dinners and White House correspondents' dinners.
Wearing donated gowns represents a change in practice from the Bush administration.
Anita McBride, chief of staff to Laura Bush during her time as first lady, said Mrs. Bush paid for all her clothes, including her two inaugural gowns: a red crystal-embroidered gown by Texan Michael Faircloth and a silver and blue V-neck creation of Oscar de la Renta.
McBride credits the Obama White House with finding a cost-saving way to "keep Mrs. Obama in all those incredible clothes and to have the use of them not once but multiple times."
The costs of a custom couture gown can be phenomenal, particularly if it is highly embellished with something like beading.
New Yorker Sarah Phillips, who designed Hillary Rodham Clinton's 1993 inaugural gown, puts the full cost of that violet beaded lace sheath in the range of $50,000, with the Presidential Inaugural Committee paying $10,000 and Phillips and the workshop covering the bulk of the costs. Phillips isn't sure whether Clinton herself paid anything toward the dress, but the Smithsonian's website describes the gown as a "gift of Hillary Rodham Clinton and the Presidential Inaugural Committee."
Lawyers who served in the Obama and Bush White Houses describe taking care in working with the first lady's office to ensure that arrangements with designers didn't run afoul of ethics rules designed to guard against conflicts of interest and questionable quid pro quos.
Beyond the unknowns about how often Mrs. Obama's clothes are donated, there are questions about how much she pays for those she purchases.
In a 2011 Washington Post story about Mrs. Obama's personal assistant, Meredith Koop, the first lady's office said Koop acted on Mrs. Obama's behalf "in arranging for purchases, including considering the best offered price and buying on discount if discounts are available."
That's still true today, the first lady's office says, without elaborating.
Several designers who have provided clothes for the first lady declined to discuss their arrangements. But given the prestige that comes with dressing Mrs. Obama, it's widely thought that designers are eager to cut the first lady a break. Former White House lawyers said any discounts provided to the first lady would have to be in line with what designers offer other top customers to avoid being considered gifts.
Paco Underhill, author of "What Women Want: The Science of Female Shopping," said the markups on designer clothes are "astronomical" — and the discounts can be steep as well.
"Some of the routine discounts that people ask for are 40 percent off," he said. "Whether they get it is subject to somebody's discretion."
First ladies have tried all sorts of tactics to hold down their clothing costs, including keeping some dresses in rotation.
Mrs. Obama wore the same dress to this year's Mother's Day tea that she'd worn to lunch with Katy Perry in October 2012. She often switches around separates, belts and other accessories to give clothes in her wardrobe a fresh look.
Recycling carries its own risks.
Mrs. Bush, in her memoir, tells of arriving at a TV studio and noticing a picture on the wall that showed she'd worn the same suit to her last interview there.
"Quickly, I exchanged tops with my press secretary, so that it would seem as if I had more wardrobe variety," she recalled.
Associated Press writers Brett Zongker in Washington and Beth Harpaz in New York and news researcher Rhonda Shafner in New York contributed to this report.
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