Generally, if the claimed deduction for an item or group of similar
items of donated property is more than $5,000, you must
get a qualified
appraisal made by a qualified appraiser, and you
must attach Section B of Form 8283 to your tax return. There are
exceptions,
discussed later. You
should keep the appraiser's report with your
written records.
For more information (including "exceptions"), please refer to this IRS Pub. 561 -
Determining the Value of Donated Property:
https://www.irs.gov/publications/p561/ar02.html#d0e1485