Fifteen seconds of Googling resulted in Deloitte's pro-bono service, which is done for CSR and employee morale rather than tax avoidance. Requests need to originate with Deloitte personnel- I know a friend who works there who might be interested in LW, but it'd be a while before I'd be comfortable asking him to recommend SI. It's a big enough company that it's likely that there are some HPMOR or LW fans that work there.