Tax liability when selling investment property

[Mark A. McElhannon]

I have basic question that I'm still unclear on. I'm looking to sell my first SFH, which I've owned and rented for 17 years, for a profit. I'm unsure of the tax liability/taxable gain due after the sell. This will determine if I will a 1031 exchange or not.

Is the taxable amount a) the profit or difference between the purchase and sell price, b) the cumulative net gain over the time owned or c) something else

looking to roll into larger SFH or Multi. Thanks!