Britney Spears' ex-husband Kevin Federline lied about his income and business expenses, according to legal documents filed by the pop star's lawyer. Attorney Stacy Phillips claims Federline "understated his income by at least $200,000 (GBP100,000)" and that he exaggerated having $800,000 (GBP400,000) worth of business expenses, reports website The legal papers, which have been submitted as part of the former couple's ongoing custody battle, also suggest Federline earned $544,074.73 (GBP272,037.36) from his company Gooseneck Productions in 2007 - and his expenses totalled $841,128.67 (GBP420,564.33). Phillips also accuses Federline of claiming business expenses including "extraordinarily high tips for food and beverage services" such as $1,100.76 (GBP550.38) on a $2,782 (GBP1,391) bill. The Toxic singer was recently ordered to pay Federline's legal bills, which Phillips says are excessive and which Federline can afford to pay himself. Spears and Federline are currently battling over custody of their two sons, Sean Preston, two, and Jayden James, one. Federline has full custody of the kids.