I think that's because in 2017 I have 3 month (>10%) personal use of the property before renting out
That makes no sense. If you did not live in the property for *any* personal pleasure use ***AFTER*** you converted the property to Residential Rental Real Estate, then you have:
ONE HUNDRED PERCENT business use and;
ZERO DAYS of personal use.
What you used the property for *before* you converted it to a rental *does* *not* *count* for anything.
So you need to amend your 2017 tax return to fix that. When you do that, it will change your depreciation carry over to 2018.
When done amending your 2017 tax return, since you have to print, sign and mail it to the IRS, you will first need a copy of the 4562 showing the *correct* amount of depreciation taken in 2017, for when you amend your 2018 tax return.
When you amend your 2018 tax return you flat out can *not* import from your amended 2017 return. So you will have to manually enter the *correct* 2017 depreciation in the box that indicates the total of all prior year's depreciation already taken.
