I figured out how Turbotax is thinking, anyway. Support was not much help and I never got the callback they promised.
$4,756 over 15 years is $317 per year. In year 1 (not using turbotax) I calculated a $79 depreciation for 3 months. Using half year that should have been $159 or mid-quarter it would be $92, so my mistake.
Turbotax, using the half year method, took $4,756 - $79 = $4,677 and divided it by the remaining 14.5 years to get $322.55 per year, rounded up to $323.
So, you just have to think like Turbotax and it makes perfect sense. Thanks to all for the feedback. Your comments gave me clues about where to look and how to test.
