You enter it as if you purchased it. Instead of purchase cost, you would enter your cost basis from building it, as if that was your purchase cost. Since you didn't inherit it or had it gifted to you, that question doesnt' really matter. You won't treat it any differently for tax purposes than if you had bought it. Not many people build their own rental properties. That's why there's no option for that. You could have won it in a poker game, that's not an option in the program either.