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What motivated Britney Spears to hit the road with her Circus tour? Was it her need to entertain the masses with her catchy pop tunes, enthusiastic jazz hands and lip-synching abilities nonpareil? Or was it the mountain of bills she's racking up each month?

On Friday, Brit's lawyers filed court papers detailing her expenses, which show that from February through December 2008, her estate shelled out more than $10 million to maintain the luxurious, if still closely monitored, lifestyle to which she's become accustomed.

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Some of the more rarefied line items include $447,633.69 for security; $186,555 for assistants and other minions; $285,594 to cover mortgage payments; $178,000 in child support to ex-husband Kevin Federline; and $625,000 to pay K-Fed's legal bills.

She also coughed up $3,400 for someone to hang Christmas lights; $138,369.67 in credit card payments; $1.06 million in "miscellaneous business expenses"; and $105,000 to rent her Malibu estate.

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Britney's coffers should be nice and full by next month, when she takes her cash cow of a tour to England. Sons Sean Preston, 3, and Jayden James, 2, are set to make the trip, as is K-Fed, who could soon be facing a change in his own personal spending routine.

The Chicago Sun-Times says Brit and her dad, Jamie Spears, have made it clear to Federline that he needs to get a handle on his "gambling habits" or they'll seek legal recourse to chop his hefty support payments.

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A source recently claimed to the National Enquirer that K-Fed had "blown through millions of dollars. When he and Britney divorced, Kevin continued the superstar lifestyle, and he spends all the money he gets."

Spears, for her part, has continued her Starbucks lifestyle. She was photographed looking a wee bit tired but well put-together in a printed dress and kitten heels while exiting a caffeine outpost in Malibu on Friday.

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