Improvements 
by Lessee(p10)

If you add buildings or make other permanent improvements to leased property, depreciate the cost of the improvements using the modified accelerated cost recovery system (MACRS). Depreciate the property over its appropriate recovery period. You cannot amortize the cost over the remaining term of the lease.

If you do not keep the improvements when you end the lease, figure your gain or loss based on your adjusted basis in the improvements at that time.

For more information, see the discussion of MACRS in Publication 946, How To Depreciate Property.

If a long-term lessee who makes permanent improvements to land later assigns all lease rights to you for money and you pay the rent required by the lease, the amount you pay for the assignment is a capital investment. If the rental value of the leased land increased since the lease began, part of your capital investment is for that increase in the rental value. The rest is for your investment in the permanent improvements.

The part that is for the increased rental value of the land is a cost of getting a lease, and you amortize it over the remaining term of the lease. You can depreciate the part that is for your investment in the improvements over the recovery period of the property as discussed earlier, without regard to the lease term.