Understand what goes in the two boxes.
COST - What you paid for the property in it's entirety.
Cost of Land - The portion of COST that is for the land.
Now even with a condo you need to allocate "something" to the land. As an example, if it's a permanent structure then you do "in fact" own the land that the building foundation physically sits on. If a 2nd floor condo, then you still own a percentage of the land that the building physically sits on. So if you allocate 10-15% of your total cost to the land, you'll be fine. Remember, this is for depreciation purposes mainly, and the value of the land the building sits on in your case, is not depreciable.
If you indicate a land value of zero, that has the potential to raise flags. See IRS Publication 527 at <a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/p527.pdf">https://www.irs.gov/pub/irs-pdf/p527.pdf</a> and check out chapter 4. It clearly states: "If you own a condominium, you also own a share of the common elements, such as land, lobbies, elevators, and service areas."
So your share of the land and all common areas are not depreciable, and if you enter "at least" 10% of your cost in the Land value box, you'll be fine.
