There’s no downward limitation on how much you have to use your business aircraft in order to take any deductions at all. That is, you should be able to take deductions for the direct operating expenses of business flights, provided that you’re properly structured, even if that amount of percentage of use is relatively de minimis. Most commonly what aircraft owners want to know is how much do they have to use their aircraft for business or qualified business use in order to be able to take accelerated depreciation. The answer to that question is either 25% of the use, plus additional business use that can get you to 50% or over 50% for qualified business use. Remember, aircraft business deductions are proportional, so even if aircraft is used 90% of the time for business, the deductibility of that last 10% of the expenses and the depreciation can be compromised by the personal use of the aircraft.