Reduction for amounts attributable to rehabilitation credit

In the case of any qualified conservation contribution (as defined in subsection (h)), the amount of the deduction allowed under this section shall be reduced by an amount which bears the same ratio to the fair market value of the contribution as—

(A) the sum of the credits allowed to the taxpayer under section 47 for the 5 preceding taxable years with respect to any building which is a part of such contribution, bears to

(B) the fair market value of the building on the date of the contribution.