In part, A.I.G. says it overpaid its federal income taxes after a 2004 accounting scandal that caused it to restate its financial records. A.I.G. says in part that it is entitled to a refund of $33 million that SICO paid in 1997 as compensation to employees, which it now says should be characterized as a deductible expense.

A.I.G.’s lawyers in the case, at Sutherland Asbill & Brennan, referred calls to the company. Asked about the lawsuit, Mark Herr, an A.I.G. spokesman, said Thursday that “A.I.G. is taking this action to ensure that it is not required to pay more than its fair share of taxes.”