TurboTax never asked me for the purchase price of rental property, where to input it?

[howverytaxing]

I use TurboTax Home & Business. We bought a cabin in 2020 that we converted from a primary home to a short-term rental when career plans changed. It's been rented out about 90% of the time and not used for personal use for over 4 years now. I just realized we have not been depreciating the cost of the house, only the improvements and furniture we bought for it, because the purchase price was not a question when I filed in 2020, maybe because we converted it that year. How can I start depreciating the value of the house on my taxes? Do I need to amend the last 4 or 5 years? I can't find anywhere in the program to input purchase price, only mortgage interest.

We also bought a triplex investment property this year with cash, no mortgage, so this problem is going to come up again when I file next year. Do I need to find a specific form since it doesn't appear to be part of the questionnaire process? 

[AmeliesUncle]

If you have never been depreciating the property (you would have entered it in the exact same place/way that you are depreciating the improvements and furniture), you'll need Form 3115 to start doing that and to 'catch up' on the missed depreciation.

TurboTax does not really support that, and I highly suggest going to a good tax professional that is experienced with Form 3115 for missed depreciation.