You should have had it appraised when you took ownership. I went through this 4 years ago when I bought my brother out of my mothers house. My CPA said this would set the value so when I sell it that would determine how I would get hit for CG's. The best way to over come the CG tax is when you sell it have money in an escrow and you have time to use the complete sale price towards another piece of property and not have to pay CG tax.

see this link:

https://www.investopedia.com/articles/personal-finance/121415/how-prevent-tax-hit-when-selling-rental-property.asp#:~:text=Real%20estate%20investors%20can%20defer,after%20the%20exchange%20is%20made.