This is an interesting idea! Some graduated tax rate for the number of dwellings + properties that way a second home or small time landlord can own say a dozen properties before the marginal taxes take too much of the marginal profits. What efficiencies are we giving up in this model?
This has a dependency on the government actually enforcing the law though, in Canada when it comes to real estate, it has been well demonstrated that they will not. Hopefully for the US it is different.
