26 C.F.R. § 403.45
In determining the nature and extent of the relief to be afforded a petitioner pursuant to § 403.44 the value of the property with respect to which the petition has been allowed is the value of such property as determined by the appraisal thereof made pursuant to § 403.26(a)(2) but if the petitioner desires re-appraisal of the property, after notification as to the conditions of allowances of the petition, and makes written request therefor, undertaking in such request to pay, or to be liable for, the total costs of such re-appraisal, the property shall be re-appraised in the manner in which the original appraisal was made, and the conditions of allowance of the petition shall be modified to the extent required by such re-appraisal.
26 C.F.R. §403.45