Closely! Donors must file IRS Form 8283 ("Noncash Charitable Contributions") if the amount of the total charitable deduction they are claiming for all noncash gifts is more than $500 for the year. If one item of donated property, or a group of similar items, exceeds $5,000 in claimed value (unless the property is publicly traded securities), donors must also summarize on Form 8283 the appraisal they obtained on that property. The appraiser and a representative of your organization must also sign that appraisal summary.
If, within 3 years of the date of the gift, your organization sells or disposes of donated property for which the donor claimed a deduction of $5,000 or more (except for publicly traded securities), you must file a separate report to the IRS, Form 8282 ("Donee Information Return"). You state the donor's name, identify the property, and tell when you received the property, when you disposed of it, and what proceeds, if any, you received on the disposition.
You can download Form 8283, its Instructions, and Form 8282 plus Instructions here.
Caution: The requirements that the IRS places on donors to substantiate charitable deductions for property gifts are complicated - we've just given you a summary here - and there are penalties for non-compliance. As your non-profit's representative, be careful about providing any advice to donors about compliance, and urge them to consult with their own advisors before making a property gift.