simply put, your depreciation value is is the *lower* of
a. What you paid for the property when you originally purchased it
b. The fair market value of the property on the date it was converted to a rental.
Typically, what you paid for the property will be the lower value, and that will be the value used by the program for setting up the depreciation schedule. This was not typical in the past, if the property was purchased before 2008 and placed in service between 2009-2016 or there-a-bouts.
Overall, nowadays I would expect what you paid for the property when you purchased it, to be the lower value. That value would be the one used as the cost-basis for depreciation.
