I am planning to buy a SUV (>6,000 lbs) and had a question about section 179 and depreciation that I couldn't find elsewhere. Let's say I buy a car for 50K on Dec 1. From Dec 1 to Dec 31 2015, I find that I used the vehicle for business use 90% of the time. Starting next year though, the vehicle usage drops to 60%.

When filing my taxes for TY2015, I understand I can take 179 for the car up to 25K. Does the 25K get derated to 22.5K or is it still 25K since the 50K purchase (even when accounted for the 90%) still exceeds 25K?

Next question, do I owe any recapture in TY 2016 for the difference between 60% and 90% use that I claimed in TY2015? As I understand it, recapture only comes in if business use drops to 50% or less, but it doesn't seem to make sense there isn't some adjustment.

Finally, what happens with standard depreciation of the rest of the amount from year to year? Does the depreciation just get derated in that individual year by the business use percentage, or is there some retroactive adjustments that need to be made?

Thanks in advance.