A friend of mine called to ask for a source of the proper order to deduct depreciation as a percentage. For example, on a $100,000 improvement cost new, physical of 10%, functional of 9% and external of 8%. I was taught that the order is 100,000 x .90 x .91 x .92 so there is no double dipping. If that is correct (as I was taught), I don't find a straightforward source that shows the sequence of percentage adjustments (or the lump sum adjustments reflected as percentages). I've looked through the 11th, 12th and 13th Editions but didn't really see it. Anyone???