one way to determine if depreciation is correct is to download IRS PUB 946 and then go to Appendix A Chart 2 (following page 67) to learn what table should be used
for example residential real estate 27.5 years would lead you to table A-6,
https://www.irs.gov/pub/irs-pdf/p946.pdf
use the column based on the month placed in service for year 1 and the % in that column for all full years rented (but not the final year). in the final year rented from 13 subtract the number of months rented and look in that column for year 1
example rented 4 months net is 9 so you would add the % for year 1 in the month 9 placed in service column. 1.061%
this will not work if the % rented varied from year to year. then multiply the sum of the %s by the total cost less land cost. There should be no depreciation for land.
