Prior depreciation needs to be correct. If you change it either way, it will affect the current year's depreciation, thus changing the tax liability.
The amount Turbo Tax estimated as prior depreciation is very close to actual (about $1K off)
Then it's perfectly possible the first year depreciation was figured incorrectly, or you're using the wrong "in service" date. For the rental property itself, that first year depreciation is figured using the mid-month convention. Remember, when dealing with the sale of rental property (which I realize you are not dealing with this on her 1040 tax return) you are required to recapture the depreciation taken, or "should" have taken. So if your in-service date is right, then the program has figured it correctly. If you need things to match, then you may need to change the in service date one or more months either side of the date you have. Now this would not be the proper thing to do, and the last thing you need as the administrator of the estate, is to get called on it by the IRS.
Typically, if the depreciation figured by the program is within a few bucks either side, then you're fine. Basically, anything less than $50 either side isn't going to make any difference in the tax liability.
Assuming you have the 2019 IRS Form 4562 titled "Depreciation and Amortization Report" for that one specific property, to get the 2020 prior years depreciation, on the 2019 form 4562 you add together the amounts in the "prior years depr" column and the "current year depr" column. That total is the amount of prior years depreciation that should be reflected in the 2020 tax return.
