All IEEE-sponsored conference with revenue or expenses above $100,000 must be audited by the IEEE Quality and Audit Department. The fee they assess is 0.6% or revenue or expenses (excluding loans) up to a maximum of $6,000. The IEEE financial reporting forms were revised in 1994 to include this audit expense, along with instructions and software for bookkeeping. Presumably all this stuff is available form IEEE Conference Services. If you have any trouble, contact the Society's Executive Officer.