Residential RE Depreciation Calculation

[Nick Gray]

I'm filing my 2017 tax return and calculating the Schedule E depreciation deduction for a duplex that I purchased in mid-December 2017.

My understanding was that my duplex would be depreciated via a 27.5-year straight-line method on a half-year convention in which the half year's worth came in the first year regardless of when I bought the property. I was thus expecting six months of depreciation despite only owning the property for two weeks in 2017 (in exchange for no depreciation 5.5 months sooner ~27 tax returns from now).

However, Turbo Tax is using a mid-month convention and only giving me two weeks of depreciation. What is the proper depreciation convention, half-year or mid-month? Can I elect to use a half-year convention since it is to my advantage in this case?