We need some quick advice. Our company as an LLC is primarily a Part 135 company and we also do Part 91 for the owner, his family and friends. The owner likes to extend himself to the state governor and other political candidates and incumbants. Sometimes we have chartered and sometimes these have been offered as freebie flights. In the past I have always operated and documented these under 135 rules just to cover my butt because I was unclear of the possible implications. Now we have a request for a freebie flight that will take us over our 135 duty day. So I'm unclear with the arguement that since we are receiving no direct compensation for this flight is it Part 91 or the fact that the owner will record the flight as either a contribution or at least write it off for operating cost and utilization for tax purposes, is it more on the 135 side. If we were strictly 91 the we could refer to 91.321 - and then it might not even apply since we are not requesting any compensation. How does the IRS look at the use of aircraft for "friends" of the owner as opposed to a corporate officer when no money changes hand, but the owner does defer/writeoff the utilization (SIFL accounting formula) cost? What documentation, other than as noted on a flight log, if any is required to differentiate 91 from 135 flights?