. in total , as of december 31 , 2007 , aon has recorded a liability for penalties and interest of $ 1 million and $ 7 million , respectively . aon and its subsidiaries file income tax returns in the u.s . federal jurisdiction as well as various state and international jurisdictions . aon has substantially concluded all u.s . federal income tax matters for years through 2004 . the internal revenue service commenced an examination of aon 2019s federal u.s