So, to clarify, column A will continue to represent the rental side of the duplex
I think what you said and the way I am interpreting it is not the same. If you enter things in the order I stated, column A will represent the entire property (both units) as a rental up to July 31, 2020. Then column B will be the single rental unit from Aug 1, 2020 through the end of the tax year. The side you started using as your personal residence is "NOT" on the SCH E anywhere, for the period of time it was your personal residence.
Do you mean that it will begin the 27.5 year depreciation all over?
Yes, exactly. But you will be depreciating a "reduced" cost basis that takes into account the prior depreciation already taken on that specific rental unit, which basically remains a rental unit.
We may sell this property in a few years and I am wondering if it will all work the way it should.
That's why it's important that you keep track of "all" depreciation taken on the property. The 4562 for column A will show the total depreciation taken on the property since you owned it, up to July 31, 2020. (current depreciation, plus prior depreciation) Then the 4562 for column B will show the depreciation taken on the unit that remains a rental, from Aug 1, 2020 through the rest of the year. If you sell the property in the future, you will need to report the "total" of "all" depreciation taken on the property on your tax return, in the tax year you actually sell the property. SO make sure to store a hard copy printout of your 2020 tax return in a safe place. I can assure you that you will need the information off those 4562's when any one of three things happens in your life
1) You convert a unit (personal to rental, or rental to personal)
2) You sell the property, or any portion thereof.
3) You die.
Would I go through the same process for a roof which was set up for depreciation in 2017?
Yes, assuming you re-roofed the entire structure in 2017. Remove it from service (convert it to personal use) on the same date you removed the primary structure from service. Then enter the roof as a completely new asset. Cut the cost basis in half to represent only the remaining rental unit. Then subtract from that, half of the depreciation already taken on that specific asset. That will give you your new adjusted cost basis on the roof. Enter that asset and depreciation starts anew on Aug 1, 2020 over the next 27.5 years.
